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2002-10-01 15:53:02 +00:00
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\title{\huge SANE Standard Version 1.03}
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1999-08-09 18:06:01 +00:00
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\author{}
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2005-10-16 17:20:06 +00:00
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\date{2005-10-16}
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1999-08-09 18:06:01 +00:00
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\begin{document}
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\maketitle
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\tableofcontents
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\listoffigures
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\listoftables
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\chapter{Preface}
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The SANE standard is being developed by a group of free-software
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developers. The process is open to the public and comments as well as
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suggestions for improvements are welcome. Information on how to join
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the SANE development process can be found in Chapter
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\ref{chap:contact}.
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The SANE standard is intended to streamline software development by
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providing a standard application programming interface to access
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raster scanner hardware. This should reduce the number of different
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driver implementations, thereby reducing the need for reimplementing
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similar code.
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\section{About This Document}
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This document is intended for developers who are creating either an
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application that requires access to raster scanner hardware and for
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developers who are implementing a SANE driver. It does not cover
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specific implementations of SANE components. Its sole purpose is to
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describe and define the SANE application interface that will enable
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any application on any platform to interoperate with any SANE backend
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for that platform.
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The remainder of this document is organized as follows.
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Chapter~\ref{chap:intro} provides introductional material.
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Chapter~\ref{chap:environ} presents the environment SANE is designed
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for. Chapter~\ref{chap:api} details the SANE Application Programmer
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Interface. Chapter~\ref{chap:net} specifies the network protocol that
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can be used to implement the SANE API in a network transparent
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fashion. Finally, Chapter~\ref{chap:contact} gives information on how
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to join the SANE development process.
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\subsection{Typographic Conventions}
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Changes since the last revision of this document are highlighted
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like this:
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% \begin{changebar}
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% Paragraphs that changed since the last revision of the documention
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% are marked like this paragraph.
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% \end{changebar}
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\chapter{Introduction}\label{chap:intro}
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SANE is an application programming interface (API) that provides
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standardized access to any raster image scanner hardware. The
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standardized interface allows to write just one driver for each
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scanner device instead of one driver for each scanner and application.
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The reduction in the number of required drivers provides significant
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savings in development time. More importantly, SANE raises the level
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at which applications can work. As such, it will enable applications
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that were previously unheard of in the UNIX world. While SANE is
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primarily targeted at a UNIX environment, the standard has been
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carefully designed to make it possible to implement the API on
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virtually any hardware or operating system.
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SANE is an acronym for ``Scanner Access Now Easy.'' Also, the hope is
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that SANE is sane in the sense that it will allow easy implementation
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of the API while accommodating all features required by today's
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scanner hardware and applications. Specifically, SANE should be broad
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enough to accommodate devices such as scanners, digital still and
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video cameras, as well as virtual devices like image file filters.
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\section{Terminology}
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An application that uses the SANE interface is called a SANE {\em
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frontend}. A driver that implements the SANE interface is called a
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SANE {\em backend}. A {\em meta backend\/} provides some means to
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manage one or more other backends.
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\chapter{The SANE Environment}\label{chap:environ}
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SANE is defined as a C-callable library interface. Accessing a raster
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scanner device typically consists of two phases: first, various
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controls of the scanner need to be setup or queried. In the second
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phase, one or more images are acquired.
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Since the device controls are widely different from device to device,
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SANE provides a generic interface that makes it easy for a frontend to
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give a user access to all controls without having to understand each
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and every device control. The design principle used here is to
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abstract each device control into a SANE {\em option\/}. An option is
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a self-describing name/value pair. For example, the brightness
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control of a camera might be represented by an option called
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\code{brightness} whose value is an integer in the range from 0 to
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255.
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With self-describing options, a backend need not be concerned with
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{\em presentation\/} issues: the backend simply provides a list of
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options that describe all the controls available in the device.
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Similarly, there are benefits to the frontend: it need not be
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concerned with the {\em meaning\/} of each option. It simply provides
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means to present and alter the options defined by the backend.
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\section{Attaching to a SANE backend}
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The process through which a SANE frontend connects to a backend is
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platform dependent. Several possibilities exist:
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\begin{itemize}
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\item {\bf Static linking:} A SANE backend may be linked directly into
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a frontend. While the simplest method of attaching to a backend, it
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is somewhat limited in functionality since the available devices is
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limited to the ones for which support has been linked in when the
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frontend was built. But even so static linking can be quite useful,
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particularly when combined with a backend that can access scanners
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via a network. Also, it is possible to support multiple backends
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simultaneously by implementing a meta backend that manages several
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backends that have been compiled in such a manner that they export
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unique function names. For example, a backend called \code{be}
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would normally export a function called \code{sane\_read()}. If
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each backend would provide such a function, static linking would
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fail due to multiple conflicting definitions of the same symbol.
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This can be resolved by having backend \code{be} include a
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header file that has lines of the form:
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\begin{quote}
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\begin{verbatim}
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#define sane_read be_sane_read
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\end{verbatim}
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\end{quote}
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With definitions of this kind, backend \code{be} will export
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function name \code{be\_sane\_read()}. Thus, all backends will
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export unique names. As long as a meta backend knows about these
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names, it is possible to combine several backends at link time and
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select and use them dynamically at runtime.
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\item {\bf Dynamic linking:} A simpler yet more powerful way to
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support multiple backends is to exploit dynamic linking on platforms
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that support it. In this case, a frontend is linked against a
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shared library that implements any SANE backend. Since each
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dynamically linked backend exports the same set of global symbols
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(all starting with the prefix \code{sane\_}), the dynamic library
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that gets loaded at runtime does not necessarily have to be the same
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one as one the frontend got linked against. In other words, it is
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possible to switch the backend by installing the appropriate backend
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dynamic library.
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More importantly, dynamic linking makes it easy to implement a meta
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backend that loads other backends {\em on demand}. This is a
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powerful mechanism since it allows adding new backends merely by
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installing a shared library and updating a configuration file.
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\item {\bf Network connection:} Arguably the ultimate way to attach to
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a scanner is by using the network to connect to a backend on a
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remote machine. This makes it possible to scan images from any host
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in the universe, as long as there is a network connection to that
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host and provided the user is permitted to access that scanner.
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\end{itemize}
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\begin{figure}[htbp]
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\begin{center}
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\leavevmode
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\psfig{file=figs/hierarchy.eps,angle=270,width=\textwidth}
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\caption{Example SANE Hiearchy}
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\label{fig:hierarchy}
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\end{center}
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\end{figure}
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The above discussion lists just a few ways for frontends to attach to
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a backend. It is of course possible to combine these solutions to
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provide an entire hierarchy of SANE backends. Such a hierarchy is
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depicted in Figure~\ref{fig:hierarchy}. The figure shows that machine
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A uses a dynamic-linking based meta backend called \code{dll} to
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access the backends called \code{pnm}, \code{mustek}, and \code{net}.
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The first two are real backends, whereas the last one is a meta
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backend that provides network transparent access to remote scanners.
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In the figure, machine B provides non-local access to its scanners
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through the SANE frontend called \code{saned}. The \code{saned} in
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turn has access to the \code{hp} and \code{autolum} backends through
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another instance of the \code{dll} backend. The \code{autolum} meta
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backend is used to automatically adjust the luminance (brightness) of
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the image data acquired by the camera backend called \code{qcam}.
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Note that a meta backend really is both a frontend and a backend at
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the same time. It is a frontend from the viewpoint of the backends
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that it manages and a backend from the viewpoint of the frontends that
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access it. The name ``meta backend'' was chosen primarily because the
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SANE standard describes the interface from the viewpoint of a (real)
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frontend.
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\section{Image Data Format}\label{sec:imageformat}\index{image data format}
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Arguably the most important aspect of an image acquisition system is
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how images are represented. The SANE approach is to define a simple
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yet powerful representation that is sufficient for vast majority of
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applications and devices. While the representation is simple, the
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interface has been defined carefully to allow extending it in the
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future without breaking backwards compatibility. Thus, it will be
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possible to accommodate future applications or devices that were not
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anticipated at the time this standard was created.
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A SANE image is a rectangular area. The rectangular area is
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subdivided into a number of rows and columns. At the intersection of
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each row and column is a quadratic pixel. A pixel consists of one or
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more sample values. Each sample value represents one channel (e.g.,
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the red channel). Each sample value has a certain bit depth. The bit
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depth is fixed for the entire image and can be as small as one bit.
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Valid bit depths are 1, 8, or 16 bits per sample. If a device's
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natural bit depth is something else, it is up to the driver to scale
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the sample values appropriately (e.g., a 4 bit sample could be scaled
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by a factor of four to represent a sample value of depth 8).
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\subsection{Image Transmission}
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The SANE API transmits an image as a sequence of frames. Each frame
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covers the same rectangular area as the entire image, but may contain
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only a subset of the channels in the final image. For example, a
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red/green/blue image could either be transmitted as a single frame
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that contains the sample values for all three channels or it could be
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transmitted as a sequence of three frames: the first frame containing
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the red channel, the second the green channel, and the third the blue
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channel.
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Conceptually, each frame is transmitted a byte at a time. Each byte
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may contain 8 sample values (for an image bit depth of 1), one full
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sample value (for an image bit depth of 8), or a partial sample value
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(for an image bit depth of 16 or bigger). In the latter case, the
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bytes of each sample value are transmitted in the machine's native
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2002-10-01 15:53:02 +00:00
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byte order. For depth 1, the leftmost pixel is stored in the most
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significant bit, and the rightmost pixel in the least significant bit.
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1999-08-09 18:06:01 +00:00
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\begin{quote}
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\begin{center}
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{\bf Backend Implementation Note}
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\end{center}
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A network-based meta backend will have to ensure that the byte order
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in image data is adjusted appropriately if necessary. For example,
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when the meta backend attaches to the server proxy, the proxy may
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inform the backend of the server's byte order. The backend can then
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apply the adjustment if necessary. In essence, this implements a
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``receiver-makes-right'' approach.
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\end{quote}
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\begin{figure}[htbp]
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\begin{center}
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\leavevmode
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\psfig{file=figs/xfer.eps,width=0.5\textwidth}
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\caption{Transfer order of image data bytes}
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\label{fig:xfer}
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\end{center}
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\end{figure}
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The order in which the sample values in a frame are transmitted is
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illustrated in Figure~\ref{fig:xfer}. As can be seen, the values are
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transmitted row by row and each row is transmitted from left-most to
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right-most column. The left-to-right, top-to-bottom transmission
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order applies when the image is viewed in its normal orientation (as
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it would be displayed on a screen, for example).
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If a frame contains multiple channels, then the channels are
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transmitted in an interleaved fashion. Figure~\ref{fig:pixels}
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illustrates this for the case where a frame contains a complete
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red/green/blue image with a bit-depth of 8. For a bit depth of 1,
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each byte contains 8 sample values of a {\em single\/} channel. In
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other words, a bit depth 1 frame is transmitted in a byte interleaved
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fashion.
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\begin{figure}[htbp]
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\begin{center}
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\leavevmode
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\psfig{file=figs/image-data.eps,width=0.8\textwidth}
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\caption{Bit and byte order or image data}
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\label{fig:pixels}
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\end{center}
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\end{figure}
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When transmitting an image frame by frame, the frontend needs to know
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what part of the image a frame represents (and how many frames it
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should expect). For that purpose, the SANE API tags every frame with
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a type. This version of the SANE standard supports the following
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frame types:
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\begin{quote}
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\begin{description}
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\item[\code{\defn{SANE\_FRAME\_GRAY}}:] The frame contains a single
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channel of data that represents sample values from a spectral band
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that covers the human visual range. The image consists of this
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frame only.
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\item[\code{\defn{SANE\_FRAME\_RGB}}:] The frame contains three
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channels of data that represent sample values from the red, green,
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and blue spectral bands. The sample values are interleaved in the
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order red, green, and blue. The image consists of this frame only.
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\item[\code{\defn{SANE\_FRAME\_RED}}:] The frame contains one channel
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of data that represents sample values from the red spectral band.
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The complete image consists of three frames:
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\code{SANE\_\-FRA\-ME\_RED}, \code{SANE\_FRAME\_GREEN}, and
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\code{SANE\_FRAME\_BLUE}. The order in which the frames are
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transmitted chosen by the backend.
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\item[\code{\defn{SANE\_FRAME\_GREEN}}:] The frame contains one
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channel of data that represents sample values from the green
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spectral band. The complete image consists of three frames:
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\code{SANE\_\-FRA\-ME\_RED}, \code{SANE\_FRAME\_GREEN}, and
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\code{SANE\_FRAME\_BLUE}. The order in which the frames are
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transmitted chosen by the backend.
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\item[\code{\defn{SANE\_FRAME\_BLUE}}:] The frame contains one channel
|
|
|
|
of data that represents sample values from the blue spectral band.
|
|
|
|
The complete image consists of three frames:
|
|
|
|
\code{SANE\_\-FRA\-ME\_RED}, \code{SANE\_FRAME\_GREEN}, and
|
|
|
|
\code{SANE\_FRAME\_BLUE}. The order in which the frames are
|
|
|
|
transmitted chosen by the backend.
|
|
|
|
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
2002-10-01 15:53:02 +00:00
|
|
|
In frames of type \code{SANE\_FRAME\_GRAY}, when the bit depth is 1 there are
|
2000-10-17 21:32:12 +00:00
|
|
|
only two sample values possible, 1 represents minimum intensity
|
|
|
|
(black) and 0 represents maximum intensity (white). For all other bit
|
|
|
|
depth and frame type combinations, a sample value of 0 represents
|
|
|
|
minimum intensity and larger values represent increasing intensity.
|
1999-08-09 18:06:01 +00:00
|
|
|
|
2002-10-01 15:53:02 +00:00
|
|
|
The combination of bit depth 1 and \code{SANE\_FRAME\_RGB} (or
|
|
|
|
\code{SANE\_FRAME\_RED}, \code{SANE\_FRAME\_GREEN}, \code{SANE\_FRAME\_BLUE})
|
|
|
|
is rarely used and may not be supported by every frontend.
|
1999-08-09 18:06:01 +00:00
|
|
|
|
|
|
|
\chapter{The SANE Application Programmer Interface (API)}\label{chap:api}
|
|
|
|
|
2000-08-12 15:11:46 +00:00
|
|
|
This Section defines version 1 of the SANE application
|
1999-08-09 18:06:01 +00:00
|
|
|
programmer interface (API). Any SANE frontend must depend on the
|
|
|
|
interface defined in this section only. Converseley, any SANE backend
|
|
|
|
must implement its functionality in accordance with this
|
|
|
|
specification. The interface as documented here is declared as a C
|
|
|
|
callable interface in a file called \filename{sane/sane.h}. This file should
|
|
|
|
normally be included via a C pre-processor directive of the form:
|
|
|
|
\begin{verbatim}
|
|
|
|
#include <sane/sane.h>
|
|
|
|
\end{verbatim}
|
|
|
|
|
|
|
|
|
|
|
|
\section{Version Control}
|
|
|
|
|
|
|
|
The SANE standard is expected to evolve over time. Whenever a change
|
|
|
|
to the SANE standard is made that may render an existing frontend or
|
|
|
|
backend incompatible with the new standard, the major version number
|
|
|
|
must be increased. Thus, any frontend/backend pair is compatible
|
|
|
|
provided the major version number of the SANE standard they implement
|
|
|
|
is the same. A frontend may implement backwards compatiblity by
|
|
|
|
allowing major numbers that are smaller than the expected major number
|
|
|
|
(provided the frontend really can cope with the older version). In
|
|
|
|
contrast, a backend always provides support for one and only one
|
|
|
|
version of the standard. If a specific application does require that
|
|
|
|
two different versions of the same backend are accessible at the same
|
|
|
|
time, it is possible to do so by installing the two versions under
|
|
|
|
different names.
|
|
|
|
|
|
|
|
SANE version control also includes a minor version number and a build
|
|
|
|
revision. While control of these numbers remains with the implementor
|
|
|
|
of a backend, the recommended use is as follows. The minor version is
|
|
|
|
incremented with each official release of a backend. The build
|
|
|
|
revision is increased with each build of a backend.
|
|
|
|
|
|
|
|
The SANE API provides the following five macros to manage version
|
|
|
|
numbers.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{\defn{SANE\_CURRENT\_MAJOR}}:] The value of this macro is the
|
|
|
|
number of the SANE standard that the interface implements.
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_VERSION\_CODE}(\var{maj},\var{min},\var{bld})}:]
|
|
|
|
\label{sec:saneversioncode}
|
|
|
|
This macro can be used to build a monotonically increasing version
|
|
|
|
code. A SANE version code consists of the SANE standard major
|
|
|
|
version number (\var{maj}), the minor version number \var{min},
|
|
|
|
and the build revision of a backend (\var{bld}). The major and
|
|
|
|
minor version numbers must be in the range 0\ldots255 and the
|
|
|
|
build revision must be in the range 0\ldots65535.
|
|
|
|
|
|
|
|
Version codes are monotonic in the sense that it is possible to
|
|
|
|
apply relational operators (e.g., equality or less-than test)
|
|
|
|
directly on the version code rather than individually on the three
|
|
|
|
components of the version code.
|
|
|
|
|
|
|
|
Note that the major version number alone determines whether a
|
|
|
|
frontend/backend pair is compatible. The minor version and the
|
|
|
|
build revision are used for informational and bug-fixing purposes
|
|
|
|
only.
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_VERSION\_MAJOR}(\var{vc})}:] This macro returns the
|
|
|
|
major version number component of the version code passed in
|
|
|
|
argument \var{vc}.
|
|
|
|
\item[\code{SANE\_VERSION\_MINOR(\var{vc})}:] This macro returns the
|
|
|
|
minor version number component of the version code passed in
|
|
|
|
argument \var{vc}.
|
|
|
|
\item[\code{SANE\_VERSION\_BUILD(\var{vc})}:] This macro returns the
|
|
|
|
build revision component of the version code passed in argument
|
|
|
|
\var{vc}.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\section{Data Types}
|
|
|
|
|
|
|
|
\subsection{Base Types}
|
|
|
|
|
|
|
|
The SANE standard is based on just two SANE-specific base types: the
|
|
|
|
SANE byte and word.
|
|
|
|
\begin{quote}
|
|
|
|
\code{typedef \var{some-scalar-type\/} \defn{SANE\_Byte};} \\
|
|
|
|
\code{typedef \var{some-scalar-type\/} \defn{SANE\_Word};}
|
|
|
|
\end{quote}
|
|
|
|
\verb|SANE_Byte| must correspond to some scalar C type that is capable
|
|
|
|
of holding values in the range 0 to 255. \verb|SANE_Word| must be
|
|
|
|
capable of holding any of the following:
|
|
|
|
\begin{itemize}
|
|
|
|
\item the truth values \verb|SANE_FALSE| and \verb|SANE_TRUE|
|
|
|
|
\item signed integers in the range $-2^{31}\ldots2^{31}-1$
|
|
|
|
\item fixed point values in the range $-32768\ldots32767.9999$ with
|
|
|
|
a resolution of $1/65536$
|
|
|
|
\item 32 bits (for bit sets)
|
|
|
|
\end{itemize}
|
|
|
|
Note that the SANE standard does not define what C type
|
|
|
|
\verb|SANE_Byte| and \verb|SANE_Word| map to. For example, on some
|
|
|
|
platforms, the latter may map to \verb|long int| whereas on others it
|
|
|
|
may map to \verb|int|. A portable SANE frontend or backend must
|
|
|
|
therefore not depend on a particular mapping.
|
|
|
|
|
|
|
|
\subsection{Boolean Type}
|
|
|
|
|
|
|
|
\code{\defn{SANE\_Bool}} is used for variables that can take one of
|
|
|
|
the two truth values \code{\defn{SANE\_FALSE}} and
|
|
|
|
\code{\defn{SANE\_TRUE}}. The former value is defined to be 0,
|
|
|
|
whereas the latter is 1.\footnote{This is different from ANSI C where
|
|
|
|
any non-zero integer value represents logical TRUE.} The C
|
|
|
|
declarations for this type are given below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
#define SANE_FALSE 0
|
|
|
|
#define SANE_TRUE 1
|
|
|
|
typedef SANE_Word SANE_Bool;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
Note that \verb|SANE_Bool| is simply an alias of \verb|SANE_Word|. It
|
|
|
|
is therefore always legal to use the latter type in place of the
|
|
|
|
former. However, for clarity, it is recommended to use
|
|
|
|
\verb|SANE_Bool| whenever a given variable or formal argument has a
|
|
|
|
fixed interpretation as a boolean object.
|
|
|
|
|
|
|
|
\subsection{Integer Type}
|
|
|
|
|
|
|
|
\code{\defn{SANE\_Int}} is used for variables that can take integer
|
|
|
|
values in the range $-2^{32}$ to $2^{31}-1$. Its C declaration is
|
|
|
|
given below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef SANE_Word SANE_Int;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
Note that \verb|SANE_Int| is simply an alias of \verb|SANE_Word|. It
|
|
|
|
is therefore always legal to use the latter type in place of the
|
|
|
|
former. However, for clarity, it is recommended to use
|
|
|
|
\verb|SANE_Int| whenever a given variable or formal argument has a
|
|
|
|
fixed interpretation as an integer object.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Fixed-point Type}
|
|
|
|
|
|
|
|
\code{\defn{SANE\_Fixed}} is used for variables that can take fixed
|
|
|
|
point values in the range $-32768$ to $32767.9999$ with a resolution
|
|
|
|
of $1/65535$. The C declarations relating to this type are given
|
|
|
|
below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
#define SANE_FIXED_SCALE_SHIFT 16
|
|
|
|
typedef SANE_Word SANE_Fixed;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
The macro \code{\defn{SANE\_FIXED\_SCALE\_SHIFT}} gives the location
|
|
|
|
of the fixed binary point. This standard defines that value to be 16,
|
|
|
|
which yields a resolution of $1/65536$.
|
|
|
|
|
|
|
|
Note that \verb|SANE_Fixed| is simply an alias of \verb|SANE_Word|.
|
|
|
|
It is therefore always legal to use the latter type in place of the
|
|
|
|
former. However, for clarity, it is recommended to use
|
|
|
|
\verb|SANE_Fixed| whenever a given variable or formal argument has a
|
|
|
|
fixed interpretation as a fixed-point object.
|
|
|
|
|
|
|
|
For convenience, SANE also defines two macros that convert fixed-point
|
|
|
|
values to and from C double floating point values.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_FIX}(\var{d})}:] Returns the largest SANE
|
|
|
|
fixed-point value that is smaller than the double value \var{d}.
|
|
|
|
No range checking is performed. If the value of \var{d} is out of
|
|
|
|
range, the result is undefined.
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_UNFIX}(\var{w})}:] Returns the nearest
|
|
|
|
double machine number that corresponds to fixed-point value
|
|
|
|
\var{w}.
|
|
|
|
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
SANE does {\em not\/} require that the following two expressions hold
|
|
|
|
true (even if the values of \var{w} and \var{d} are in range):
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_UNFIX(SANE_FIX(d)) == d
|
|
|
|
SANE_FIX(SANE_UNFIX(w)) == w
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
In other words, conversion between fixed and double values may be
|
|
|
|
lossy. It is therefore recommended to avoid repeated conversions
|
|
|
|
between the two representations.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Text}
|
|
|
|
|
|
|
|
\subsubsection{Character Type}
|
|
|
|
|
|
|
|
Type \code{\defn{SANE\_Char}} represents a single text character or
|
|
|
|
symbol. At present, this type maps directly to the underlying C
|
|
|
|
\verb|char| type (typically one byte). The encoding for such
|
|
|
|
characters is currently fixed as ISO LATIN-1. Future versions of this
|
|
|
|
standard may map this type to a wider type and allow multi-byte
|
|
|
|
encodings to support internationalization. As a result of this, care
|
|
|
|
should be taken to avoid the assumption that
|
2000-11-12 15:56:05 +00:00
|
|
|
\verb|sizeof(SANE_Char)==sizeof(char)|.
|
1999-08-09 18:06:01 +00:00
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef char SANE_Char;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\subsubsection{String Type}
|
|
|
|
|
|
|
|
Type \code{\defn{SANE\_String}} represents a text string as a sequence
|
|
|
|
of C \verb|char| values. The end of the sequence is indicated by a
|
|
|
|
\verb|'\0'| (\defn{NUL}) character.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef SANE_Char *SANE_String;
|
|
|
|
typedef const SANE_Char *SANE_String_Const;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
The type \code{\defn{SANE\_String\_Const}} is provided by SANE to
|
|
|
|
enable declaring strings whose contents is unchangable. Note that in
|
|
|
|
ANSI C, the declaration
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
const SANE_String str;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
declares a string pointer that is constant (not a string pointer that
|
|
|
|
points to a constant value).
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Scanner Handle Type}
|
|
|
|
|
|
|
|
Access to a scanner is provided through an opaque type called
|
|
|
|
\code{\defn{SANE\_Handle}}. The C declaration of this type is given
|
|
|
|
below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef void *SANE_Handle;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
While this type is declared to be a void pointer, an application must
|
|
|
|
not attempt to interpret the value of a \verb|SANE_Handle|. In
|
|
|
|
particular, SANE does not require that a value of this type is a legal
|
|
|
|
pointer value.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Status Type}
|
|
|
|
|
|
|
|
Most SANE operations return a value of type \code{\defn{SANE\_Status}}
|
|
|
|
to indicate whether the completion status of the operation. If an
|
|
|
|
operation completes successfully, \verb|SANE_STATUS_GOOD| is returned.
|
|
|
|
In case of an error, a value is returned that indicates the nature of
|
|
|
|
the problem. The complete list of available status codes is listed in
|
|
|
|
Table \ref{tab:status}. It is recommended to use function
|
|
|
|
\code{sane\_strstatus()} to convert status codes into a legible
|
|
|
|
string.
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\begin{tabular}{|l|r|l|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} & \multicolumn{1}{c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{c|}{\bf Description} \\
|
|
|
|
\hline\hline
|
|
|
|
\code{\defn{SANE\_STATUS\_GOOD}}
|
|
|
|
& 0 & Operation completed succesfully. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_UNSUPPORTED}}
|
|
|
|
& 1 & Operation is not supported. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_CANCELLED}}
|
|
|
|
& 2 & Operation was cancelled. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_DEVICE\_BUSY}}
|
|
|
|
& 3 & Device is busy---retry later. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_INVAL}}
|
|
|
|
& 4 & Data or argument is invalid. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_EOF}}
|
|
|
|
& 5 & No more data available (end-of-file). \\
|
|
|
|
\code{\defn{SANE\_STATUS\_JAMMED}}
|
|
|
|
& 6 & Document feeder jammed. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_NO\_DOCS}}
|
|
|
|
& 7 & Document feeder out of documents. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_COVER\_OPEN}}
|
|
|
|
& 8 & Scanner cover is open. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_IO\_ERROR}}
|
|
|
|
& 9 & Error during device I/O. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_NO\_MEM}}
|
|
|
|
& 10 & Out of memory. \\
|
|
|
|
\code{\defn{SANE\_STATUS\_ACCESS\_DENIED}}
|
|
|
|
& 11 & Access to resource has been denied. \\
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Status Codes}\label{tab:status}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Device Descriptor Type}
|
|
|
|
|
|
|
|
Each SANE device is represented by a structure of type
|
|
|
|
\code{\defn{SANE\_Device}}. The C declaration of this type is given
|
|
|
|
below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef struct
|
|
|
|
{
|
|
|
|
SANE_String_Const name;
|
|
|
|
SANE_String_Const vendor;
|
|
|
|
SANE_String_Const model;
|
|
|
|
SANE_String_Const type;
|
|
|
|
}
|
|
|
|
SANE_Device;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
\index{device-name}
|
|
|
|
The structure provides the unique name of the scanner in member
|
|
|
|
\code{name}. It is this unique name that should be passed in a call
|
|
|
|
to \code{sane\_open()}. The format of this name is completely up to
|
|
|
|
the backend. The only constraints are that the name is unique among
|
|
|
|
all devices supported by the backend and that the name is a legal SANE
|
|
|
|
text string. To simplify presentation of unique names, their length
|
|
|
|
should not be excessive. It is {\em recommended\/} that backends keep
|
|
|
|
unique names below 32 characters in length. However, applications
|
|
|
|
{\em must\/} be able to cope with arbitrary length unique names.
|
|
|
|
|
|
|
|
The remaining members in the device structure provide additional
|
|
|
|
information on the device corresponding to the unique name.
|
|
|
|
Specifically, members \code{vendor}, \code{model}, and \code{type} are
|
|
|
|
single-line strings that give information on the vendor
|
|
|
|
(manufacturer), model, and the type of the device. For consistency's
|
|
|
|
sake, the following strings should be used when appropriate (the lists
|
|
|
|
will be expanded as need arises):
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\hspace{\fill}
|
|
|
|
\begin{tabular}[t]{|ll|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{2}{|c|}{\bf \defn{Vendor Strings}} \\
|
|
|
|
\hline\hline
|
2005-10-16 17:20:06 +00:00
|
|
|
\code{AGFA} & \code{Microtek} \\
|
|
|
|
\code{Abaton} & \code{Minolta} \\
|
|
|
|
\code{Acer} & \code{Mitsubishi} \\
|
|
|
|
\code{Apple} & \code{Mustek} \\
|
|
|
|
\code{Artec} & \code{NEC} \\
|
|
|
|
\code{Avision} & \code{Nikon} \\
|
|
|
|
\code{CANON} & \code{Plustek} \\
|
|
|
|
\code{Connectix} & \code{Polaroid} \\
|
|
|
|
\code{Epson} & \code{Relisys} \\
|
|
|
|
\code{Fujitsu} & \code{Ricoh} \\
|
|
|
|
\code{Hewlett-Packard} & \code{Sharp} \\
|
|
|
|
\code{IBM} & \code{Siemens} \\
|
|
|
|
\code{Kodak} & \code{Tamarack} \\
|
|
|
|
\code{Lexmark} & \code{UMAX} \\
|
2003-02-22 18:43:45 +00:00
|
|
|
\code{Logitech} & \code{Noname} \\
|
1999-08-09 18:06:01 +00:00
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\hspace{\fill}
|
|
|
|
\begin{tabular}[t]{|l|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf \defn{Type Strings}} \\
|
|
|
|
\hline\hline
|
Added some vendors (Abaton, Acer, Apple, Avision, CANON, Fujitsu, IBM, NEC,
Nikon, Plustek, Polaroid, Ricoh, Sharp, Siemens, Tamarack) and device types
(film scanner, sheetfed scanner) to the SANE standard. Updated date.
Henning Meier-Geinitz <henning@meier-geinitz.de>
2002-02-19 20:07:47 +00:00
|
|
|
\code{film scanner} \\
|
1999-08-09 18:06:01 +00:00
|
|
|
\code{flatbed scanner} \\
|
|
|
|
\code{frame grabber} \\
|
|
|
|
\code{handheld scanner} \\
|
2002-03-08 22:44:38 +00:00
|
|
|
\code{multi-function peripheral} \\
|
Added some vendors (Abaton, Acer, Apple, Avision, CANON, Fujitsu, IBM, NEC,
Nikon, Plustek, Polaroid, Ricoh, Sharp, Siemens, Tamarack) and device types
(film scanner, sheetfed scanner) to the SANE standard. Updated date.
Henning Meier-Geinitz <henning@meier-geinitz.de>
2002-02-19 20:07:47 +00:00
|
|
|
\code{sheetfed scanner} \\
|
1999-08-09 18:06:01 +00:00
|
|
|
\code{still camera} \\
|
|
|
|
\code{video camera} \\
|
|
|
|
\code{virtual device} \\
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\hspace{\fill}
|
|
|
|
\caption{Predefined Device Information Strings}
|
|
|
|
\label{tab:devinfo}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
Note that vendor string \code{Noname} can be used for virtual devices
|
|
|
|
that have no physical vendor associated. Also, there are no
|
|
|
|
predefined model name strings since those are vendor specific and
|
|
|
|
therefore completely under control of the respective backends.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{Option Descriptor Type}\label{sec:odesc}
|
|
|
|
|
|
|
|
Option descriptors are at the same time the most intricate and
|
|
|
|
powerful type in the SANE standard. Options are used to control
|
|
|
|
virtually all aspects of device operation. Much of the power of the
|
|
|
|
SANE API stems from the fact that most device controls are completely
|
|
|
|
described by their respective option descriptor. Thus, a frontend can
|
|
|
|
control a scanner abstractly, without requiring knowledge as to what
|
|
|
|
the purpose of any given option is. Conversely, a scanner can
|
|
|
|
describe its controls without requiring knowledge of how the frontend
|
|
|
|
operates. The C declaration of the
|
|
|
|
\code{\defn{SANE\_Option\_Descriptor}} type is given below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef struct
|
|
|
|
{
|
|
|
|
SANE_String_Const name;
|
|
|
|
SANE_String_Const title;
|
|
|
|
SANE_String_Const desc;
|
|
|
|
SANE_Value_Type type;
|
|
|
|
SANE_Unit unit;
|
|
|
|
SANE_Int size;
|
|
|
|
SANE_Int cap;
|
|
|
|
SANE_Constraint_Type constraint_type;
|
|
|
|
union
|
|
|
|
{
|
|
|
|
const SANE_String_Const *string_list;
|
|
|
|
const SANE_Word *word_list;
|
|
|
|
const SANE_Range *range;
|
|
|
|
}
|
|
|
|
constraint;
|
|
|
|
}
|
|
|
|
SANE_Option_Descriptor;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\subsubsection{Option Name}
|
|
|
|
|
|
|
|
Member \code{name} is a string that uniquely identifies the option.
|
|
|
|
The name must be unique for a given device (i.e., the option names
|
|
|
|
across different backends or devices need not be unique). The option
|
|
|
|
name must consist of lower-case ASCII letters (\code{a}--\code{z}),
|
|
|
|
digits (\code{0}--\code{9}), or the dash character (\code{-}) only.
|
|
|
|
The first character must be a lower-case ASCII character (i.e., not a
|
|
|
|
digit or a dash).
|
|
|
|
|
|
|
|
\subsubsection{Option Title}
|
|
|
|
|
|
|
|
Member \code{title} is a single-line string that can be used by the
|
|
|
|
frontend as a title string. This should typically be a short (one or
|
|
|
|
two-word) string that is chosen based on the function of the option.
|
|
|
|
|
|
|
|
\subsubsection{Option Description}
|
|
|
|
|
|
|
|
Member \code{desc} is a (potentially very) long string that can be
|
|
|
|
used as a help text to describe the option. It is the responsibility
|
|
|
|
of the frontend to break the string into managable-length lines.
|
|
|
|
Newline characters in this string should be interpreted as paragraph
|
|
|
|
breaks.
|
|
|
|
|
|
|
|
\subsubsection{Option Value Type}
|
|
|
|
|
|
|
|
Member \code{type} specifies the type of the option value. The
|
|
|
|
possible values for type \code{\defn{SANE\_Value\_Type}} are described
|
|
|
|
in Table \ref{tab:valuetype}.
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|l|p{0.6\textwidth}|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{c|}{\bf Description} \\
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_BOOL}} & 0 & Option value is of type
|
|
|
|
\verb|SANE_Bool|. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_INT}} & 1 & Option value is of type
|
|
|
|
\verb|SANE_Int|. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_FIXED}}&2 & Option value is of type
|
|
|
|
\verb|SANE_Fixed|. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_STRING}}&3 & Option value is of type
|
|
|
|
\verb|SANE_String|. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_BUTTON}} & 4 & An option of this type has no value.
|
|
|
|
Instead, setting an option of this type has an option-specific
|
|
|
|
side-effect. For example, a button-typed option could be used by a
|
|
|
|
backend to provide a means to select default values or to the tell an
|
|
|
|
automatic document feeder to advance to the next sheet of paper. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_TYPE\_GROUP}} & 5 & An option of this type has no value.
|
|
|
|
This type is used to group logically related options. A group option
|
|
|
|
is in effect up to the point where another group option is encountered
|
|
|
|
(or up to the end of the option list, if there are no other group
|
|
|
|
options). For group options, only members \code{title} and
|
|
|
|
\code{type} are valid in the option descriptor. \\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Option Value Types (\code{SANE\_Value\_Type})}
|
|
|
|
\label{tab:valuetype}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
\subsubsection{Option Value Unit}
|
|
|
|
|
|
|
|
Member \code{unit} specifies what the physical unit of the option
|
|
|
|
value is. The possible values for type \code{\defn{SANE\_U\-nit}} are
|
|
|
|
described in Table \ref{tab:units}. Note that the specified unit is
|
|
|
|
what the SANE backend expects. It is entirely up to a frontend as to
|
|
|
|
how these units a presented to the user. For example, SANE expresses
|
|
|
|
all lengths in millimeters. A frontend is generally expected to
|
|
|
|
provide appropriate conversion routines so that a user can express
|
|
|
|
quantities in a customary unit (e.g., inches or centimeters).
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|l|l|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Description} \\
|
|
|
|
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_UNIT\_NONE}} & 0 & Value is unit-less (e.g., page count).\\
|
|
|
|
\code{\defn{SANE\_UNIT\_PIXEL}} & 1 & Value is in number of pixels. \\
|
|
|
|
\code{\defn{SANE\_UNIT\_BIT}} & 2 & Value is in number of bits. \\
|
|
|
|
\code{\defn{SANE\_UNIT\_MM}} & 3 & Value is in millimeters. \\
|
|
|
|
\code{\defn{SANE\_UNIT\_DPI}} & 4 & Value is a resolution in dots/inch. \\
|
|
|
|
\code{\defn{SANE\_UNIT\_PERCENT}}& 5 & Value is a percentage. \\
|
|
|
|
\code{\defn{SANE\_UNIT\_MICROSECOND}}& 6 & Value is time in $\mu$-seconds. \\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Physical Units (\code{SANE\_Unit})}
|
|
|
|
\label{tab:units}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
\subsubsection{Option Value Size}\label{sec:valuesize}
|
|
|
|
|
|
|
|
Member \code{size} specifies the size of the option value (in bytes).
|
|
|
|
This member has a slightly different interpretation depending on the
|
|
|
|
type of the option value:
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_TYPE\_STRING}:] The size is the maximum size of
|
|
|
|
the string. For the purpose of string size calcuations, the
|
|
|
|
terminating \code{NUL} character is considered to be part of the
|
|
|
|
string. Note that the terminating \code{NUL} character must
|
|
|
|
always be present in string option values.
|
|
|
|
\item[\code{SANE\_TYPE\_INT}, \code{SANE\_TYPE\_FIXED}:] The size
|
|
|
|
must be a positive integer multiple of the size of a
|
|
|
|
\verb|SANE_Word|. The option value is a vector of length
|
|
|
|
\[ \code{size}/\code{sizeof(SANE\_Word)}. \]
|
|
|
|
\item[\code{SANE\_TYPE\_BOOL}:] The size must be set to
|
|
|
|
\code{sizeof(SANE\_Word)}.
|
|
|
|
\item[\code{SANE\_TYPE\_BUTTON}, \code{SANE\_TYPE\_GROUP}:] The
|
|
|
|
option size is ignored.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\subsubsection{Option Capabilities}
|
|
|
|
|
|
|
|
Member \code{cap} describes what capabilities the option posseses.
|
|
|
|
This is a bitset that is formed as the inclusive logical OR of the
|
|
|
|
capabilities described in Table \ref{tab:capabilities}. The SANE API
|
|
|
|
provides the following to macros to test certain features of a given
|
|
|
|
capability bitset:
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_OPTION\_IS\_ACTIVE}(\var{cap})}:] This macro
|
|
|
|
returns \code{SANE\_TRUE} if and only if the option with the
|
|
|
|
capability set \var{cap} is currently active.
|
|
|
|
|
|
|
|
\item[\code{\defn{SANE\_OPTION\_IS\_SETTABLE}(\var{cap})}:] This
|
|
|
|
macro returns \code{SANE\_TRUE} if and only if the option with the
|
|
|
|
capability set \var{cap} is software settable.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|r|p{0.59\textwidth}|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{c|}{\bf Description} \\
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_SOFT\_SELECT}} & 1 & The option
|
|
|
|
value can be set by a call to \code{sane\_con\-trol\_opt\-ion()}.\\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_HARD\_SELECT}} & 2 & The option value can be set by
|
|
|
|
user-intervention (e.g., by flipping a switch). The user-interface
|
|
|
|
should prompt the user to execute the appropriate action to set such
|
|
|
|
an option. This capability is mutually exclusive with
|
|
|
|
SANE\_CAP\_SOFT\_SELECT (either one of them can be set, but not both
|
|
|
|
simultaneously). \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_SOFT\_DETECT}} & 4 & The option
|
|
|
|
value can be detected by software. If
|
|
|
|
\code{SANE\_\-CAP\_\-SO\-FT\_SEL\-ECT} is set, this capability {\em must\/}
|
|
|
|
be set. If \code{SANE\_CAP\_HARD\_SELECT} is set, this capability
|
|
|
|
may or may not be set. If this capability is set but neither
|
|
|
|
\code{SANE\_CAP\_SO\-FT\_SEL\-ECT} nor \code{SANE\_CAP\_HA\-RD\_SEL\-ECT}
|
|
|
|
are, then there is no way to control the option. That is, the
|
|
|
|
option provides read-out of the current value only. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_EMULATED}} & 8 & If set, this capability indicates
|
|
|
|
that an option is not directly supported by the device and is
|
|
|
|
instead emulated in the backend. A sophisticated frontend may
|
|
|
|
elect to use its own (presumably better) emulation in lieu of an emulated
|
|
|
|
option. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_AUTOMATIC}} & 16 & If set, this capability indicates
|
|
|
|
that the backend (or the device) is capable to picking a reasonable
|
|
|
|
option value automatically. For such options, it is possible to
|
|
|
|
select automatic operation by calling \code{sane\_control\_option()}
|
|
|
|
with an action value of \code{SANE\_ACTION\_SET\_AUTO}. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_INACTIVE}} & 32 & If set, this capability indicates
|
|
|
|
that the option is not currently active (e.g., because it's
|
|
|
|
meaningful only if another option is set to some other value). \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CAP\_ADVANCED}} & 64 &
|
|
|
|
If set, this capability indicates that the option should be
|
|
|
|
considered an ``advanced user option.'' A frontend typically
|
|
|
|
displays such options in a less conspicuous way than regular options
|
|
|
|
(e.g., a command line interface may list such options last or a
|
|
|
|
graphical interface may make them available in a seperate ``advanced
|
|
|
|
settings'' dialog).
|
|
|
|
\\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Option Capabilities}
|
|
|
|
\label{tab:capabilities}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
\subsubsection{Option Value Constraints}
|
|
|
|
|
|
|
|
It is often useful to constrain the values that an option can take.
|
|
|
|
For example, constraints can be used by a frontend to determine how to
|
|
|
|
represent a given option. Member \code{constraint\_type} indicates
|
|
|
|
what constraint is in effect for the option. The constrained values
|
|
|
|
that are allowed for the option are described by one of the union
|
|
|
|
members of member \code{constraint}. The possible values of type
|
|
|
|
\code{\defn{SANE\_Constraint\_Type}} and the interpretation of the
|
|
|
|
\code{constraint} union is described in Table~\ref{tab:constraints}.
|
|
|
|
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|r|p{0.5\textwidth}|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Description} \\
|
|
|
|
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CONSTRAINT\_NONE}} & 0 & The value is unconstrained.
|
|
|
|
The option can take any of the values possible for the option's
|
|
|
|
type. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CONSTRAINT\_RANGE}} & 1 & This constraint is
|
|
|
|
applicable to integer and fixed-point valued options only. It
|
|
|
|
constrains the option value to a possibly quantized range of
|
|
|
|
numbers. Option descriptor member \code{constraint.range} points to
|
|
|
|
a range of the type \code{\defn{SANE\_Range}}. This type is illustrated
|
|
|
|
below:
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef struct
|
|
|
|
{
|
|
|
|
SANE_Word min;
|
|
|
|
SANE_Word max;
|
|
|
|
SANE_Word quant;
|
|
|
|
}
|
|
|
|
SANE_Range;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
All three members in this structure are interpreted according to the
|
|
|
|
option value type (\verb|SANE_TYPE_INT| or \verb|SANE_TYPE_FIXED|).
|
|
|
|
Members \code{min} and \code{max} specify the minimum and maximum
|
|
|
|
values, respectively. If member \code{quant} is non-zero, it
|
|
|
|
specifies the quantization value. If $l$ is the minimum value, $u$
|
|
|
|
the maximum value and $q$ the (non-zero) quantization of a range,
|
|
|
|
then the legal values are $v=k\cdot q+l$ for all non-negative
|
|
|
|
integer values of $k$ such that $v<=u$. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CONSTRAINT\_WORD\_LIST}} & 2 & This constraint is applicable
|
|
|
|
to integer and fixed-point valued options only. It constrains the
|
|
|
|
option value to a list of numeric values. Option descriptor member
|
|
|
|
\code{constraint.word\_list} points to a list of words that
|
|
|
|
enumerates the legal values. The first element in that list is an
|
|
|
|
integer (\verb|SANE_Int|) that specifies the length of the list (not
|
|
|
|
counting the length itself). The remaining elements in the list are
|
|
|
|
interpreted according to the type of the option value
|
|
|
|
(\verb|SANE_TYPE_INT| or \verb|SANE_TYPE_FIXED|). \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_CONSTRAINT\_STRING\_LIST}} & 3 & This constraint is
|
|
|
|
applicable to string-valued options only. It constrains the option
|
|
|
|
value to a list of strings. The option descriptor member
|
|
|
|
\code{con\-strai\-nt.str\-ing\_list} points to a \code{NULL} terminated
|
|
|
|
list of strings that enumerate the legal values for the option
|
|
|
|
value.
|
|
|
|
\\\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Option Value Constraints}
|
|
|
|
\label{tab:constraints}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
|
|
|
|
\section{Operations}
|
|
|
|
|
|
|
|
\subsection{\code{sane\_init}}
|
|
|
|
|
2002-10-15 08:36:40 +00:00
|
|
|
This function must be called before any other SANE function can be called.
|
|
|
|
The behavior of a SANE backend is undefined if this function is not called
|
|
|
|
first or if the status code returned by \code{sane\_init} is different from
|
|
|
|
\code{\defn{SANE\_STATUS\_GOOD}}. The version code of the backend is returned
|
|
|
|
in the value pointed to by \code{version\_code}. If that pointer is
|
|
|
|
\code{NULL}, no version code is returned. Argument \code{authorize} is either
|
|
|
|
a pointer to a function that is invoked when the backend requires
|
|
|
|
authentication for a specific resource or \code{NULL} if the frontend does not
|
|
|
|
support authentication.
|
1999-08-09 18:06:01 +00:00
|
|
|
\begin{quote}\index{sane\_init}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_init (SANE_Int * version_code,
|
|
|
|
SANE_Authorization_Callback authorize);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
The authorization function may be called by a backend in response to
|
|
|
|
any of the following calls:
|
|
|
|
\begin{quote}
|
|
|
|
\code{sane\_open}, \code{sane\_control\_option}, \code{sane\_start}
|
|
|
|
\end{quote}
|
|
|
|
If a backend was initialized without authorization function, then
|
|
|
|
authorization requests that cannot be handled by the backend itself
|
|
|
|
will fail automatically and the user may be prevented from accessing
|
|
|
|
protected resources. Backends are encouraged to implement means of
|
|
|
|
authentication that do not require user assistance. E.g., on a
|
|
|
|
multi-user system that authenticates users through a login process a
|
|
|
|
backend could automatically lookup the apporpriate password based on
|
|
|
|
resource- and user-name.
|
|
|
|
|
|
|
|
The authentication function type has the following declaration:
|
|
|
|
\begin{quote}\index{SANE\_Authorization\_Callback}
|
|
|
|
\index{domain}\index{username}\index{password}
|
|
|
|
\begin{verbatim}
|
2000-11-20 18:49:26 +00:00
|
|
|
#define SANE_MAX_USERNAME_LEN 128
|
|
|
|
#define SANE_MAX_PASSWORD_LEN 128
|
1999-08-09 18:06:01 +00:00
|
|
|
|
|
|
|
typedef void (*SANE_Authorization_Callback)
|
|
|
|
(SANE_String_Const resource,
|
|
|
|
SANE_Char username[SANE_MAX_USERNAME_LEN],
|
|
|
|
SANE_Char password[SANE_MAX_PASSWORD_LEN]);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
Three arguments are passed to the authorization function:
|
|
|
|
\code{resource} is a string specifying the name of the resource that
|
|
|
|
requires authorization. A frontend should use this string to build a
|
|
|
|
user-prompt requesting a username and a password. The \code{username}
|
|
|
|
and \code{password} arguments are (pointers to) an array of
|
|
|
|
\code{SANE\_MAX\_USERNAME\_LEN} and \code{SANE\_MAX\_PASSWORD\_LEN}
|
|
|
|
characters, respectively. The authorization call should place the
|
|
|
|
entered username and password in these arrays. The returned strings
|
|
|
|
{\em must\/} be ASCII-NUL terminated.
|
|
|
|
|
|
|
|
\subsection{\code{sane\_exit}}
|
|
|
|
|
|
|
|
This function must be called to terminate use of a backend. The
|
|
|
|
function will first close all device handles that still might be open
|
|
|
|
(it is recommended to close device handles explicitly through a call
|
|
|
|
to \code{sane\_clo\-se()}, but backends are required to release all
|
|
|
|
resources upon a call to this function). After this function returns,
|
|
|
|
no function other than \code{sane\_init()} may be called (regardless
|
|
|
|
of the status value returned by \code{sane\_exit()}. Neglecting to
|
|
|
|
call this function may result in some resources not being released
|
|
|
|
properly.
|
|
|
|
\begin{quote}\index{sane\_exit}
|
|
|
|
\begin{verbatim}
|
|
|
|
void sane_exit (void);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_get\_devices}}
|
|
|
|
|
|
|
|
This function can be used to query the list of devices that are
|
|
|
|
available. If the function executes successfully, it stores a pointer
|
|
|
|
to a \code{NULL} terminated array of pointers to \verb|SANE_Device|
|
|
|
|
structures in \code{*device\_list}. The returned list is guaranteed
|
|
|
|
to remain unchanged and valid until (a) another call to this function
|
|
|
|
is performed or (b) a call to \code{sane\_exit()} is performed. This
|
|
|
|
function can be called repeatedly to detect when new devices become
|
|
|
|
available. If argument \code{local\_only} is true, only local devices
|
|
|
|
are returned (devices directly attached to the machine that SANE is
|
|
|
|
running on). If it is false, the device list includes all remote
|
|
|
|
devices that are accessible to the SANE library.
|
|
|
|
\begin{quote}\index{sane\_get\_devices}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_get_devices (const SANE_Device *** device_list,
|
|
|
|
SANE_Bool local_only);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
This function may fail with \code{SANE\_STATUS\_NO\_MEM} if an
|
|
|
|
insufficient amount of memory is available.
|
|
|
|
|
|
|
|
\begin{quote}
|
|
|
|
\begin{center}
|
|
|
|
{\bf Backend Implementation Note}
|
|
|
|
\end{center}
|
|
|
|
SANE does not require that this function is called before a
|
|
|
|
\code{sane\_open()} call is performed. A device name may be
|
|
|
|
specified explicitly by a user which would make it unnecessary and
|
|
|
|
undesirable to call this function first.
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_open}}
|
|
|
|
|
|
|
|
This function is used to establish a connection to a particular
|
|
|
|
device. The name of the device to be opened is passed in argument
|
|
|
|
\code{name}. If the call completes successfully, a handle for the
|
|
|
|
device is returned in \code{*h}. As a special case, specifying a
|
|
|
|
zero-length string as the device requests opening the first available
|
|
|
|
device (if there is such a device).
|
|
|
|
\begin{quote}\index{sane\_open}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_open (SANE_String_Const name, SANE_Handle * h);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
This function may fail with one of the following status codes.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_DEVICE\_BUSY}:] The device is currently
|
|
|
|
busy (in use by somebody else).
|
|
|
|
\item[\code{SANE\_STATUS\_INVAL}:] The device name is not valid.
|
|
|
|
\item[\code{SANE\_STATUS\_IO\_ERROR}:] An error occured while
|
|
|
|
communicating with the device.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_MEM}:] An insufficent amount of memory
|
|
|
|
is available.
|
|
|
|
\item[\code{SANE\_STATUS\_ACCESS\_DENIED}:] Access to the device has
|
|
|
|
been denied due to insufficient or invalid authentication.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_close}}
|
|
|
|
|
|
|
|
This function terminates the association between the device handle
|
|
|
|
passed in argument \code{h} and the device it represents. If the
|
|
|
|
device is presently active, a call to \code{sane\_cancel()} is
|
|
|
|
performed first. After this function returns, handle \code{h} must
|
|
|
|
not be used anymore.
|
|
|
|
|
|
|
|
\begin{quote}\index{sane\_close}
|
|
|
|
\begin{verbatim}
|
|
|
|
void sane_close (SANE_Handle h);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\subsection{\code{sane\_get\_option\_descriptor}}
|
|
|
|
|
|
|
|
This function is used to access option descriptors. The function
|
|
|
|
returns the option descriptor for option number \code{n} of the device
|
|
|
|
represented by handle \code{h}. Option number 0 is guaranteed to be a
|
|
|
|
valid option. Its value is an integer that specifies the number of
|
|
|
|
options that are available for device handle \code{h} (the count
|
|
|
|
includes option 0). If $n$ is not a valid option index, the function
|
|
|
|
returns \code{NULL}. The returned option descriptor is guaranteed to
|
|
|
|
remain valid (and at the returned address) until the device is closed.
|
|
|
|
|
|
|
|
\begin{quote}\index{sane\_get\_option\_descriptor}
|
|
|
|
\begin{verbatim}
|
|
|
|
const SANE_Option_Descriptor *
|
|
|
|
sane_get_option_descriptor (SANE_Handle h, SANE_Int n);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\subsection{\code{sane\_control\_option}}\label{sec:control}
|
|
|
|
|
|
|
|
This function is used to set or inquire the current value of option
|
|
|
|
number \code{n} of the device represented by handle \code{h}. The
|
|
|
|
manner in which the option is controlled is specified by parameter
|
|
|
|
\code{a}. The possible values of this parameter are described in more
|
|
|
|
detail below. The value of the option is passed through argument
|
|
|
|
\code{v}. It is a pointer to the memory that holds the option value.
|
|
|
|
The memory area pointed to by \code{v} must be big enough to hold the
|
|
|
|
entire option value (determined by member \code{size} in the
|
|
|
|
corresponding option descriptor). The only exception to this rule is
|
|
|
|
that when setting the value of a string option, the string pointed to
|
|
|
|
by argument \code{v} may be shorter since the backend will stop
|
|
|
|
reading the option value upon encountering the first \code{NUL}
|
|
|
|
terminator in the string. If argument \code{i} is not \code{NULL},
|
|
|
|
the value of \code{*i} will be set to provide details on how well the
|
|
|
|
request has been met. The meaning of this argument is described in
|
|
|
|
more detail below.
|
|
|
|
\begin{quote}\index{sane\_control\_option}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_control_option (SANE_Handle h, SANE_Int n,
|
|
|
|
SANE_Action a, void *v,
|
|
|
|
SANE_Int * i);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
The way the option is affected by a call to this function is
|
|
|
|
controlled by parameter \code{a} which is a value of type
|
|
|
|
\code{\defn{SANE\_Action}}. The possible values and their meaning is
|
|
|
|
described in Table~\ref{tab:actions}.
|
|
|
|
|
|
|
|
\begin{table}[h]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|r|p{0.5\textwidth}|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Description} \\
|
|
|
|
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_ACTION\_GET\_VALUE}} & 0 & Get current option value. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_ACTION\_SET\_VALUE}} & 1 & Set option value. The
|
|
|
|
option value passed through argument \code{v} may be modified by the
|
|
|
|
backend if the value cannot be set exactly. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_ACTION\_SET\_AUTO}} & 2 & Turn on automatic mode. Backend
|
|
|
|
or device will automatically select an appropriate value. This mode
|
|
|
|
remains effective until overridden by an explicit set value request.
|
|
|
|
The value of parameter \code{v} is completely ignored in this case and
|
|
|
|
may be \code{NULL}. \\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Action Values (\code{SANE\_Action})}
|
|
|
|
\label{tab:actions}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
After setting a value via an action value of
|
|
|
|
\verb|SANE_ACTION_SET_VALUE|, additional information on how well the
|
|
|
|
request has been met is returned in \code{*i} (if \code{i} is
|
|
|
|
non-\code{NULL}). The returned value is a bitset that may contain any
|
|
|
|
combination of the values described in Table~\ref{tab:info}.
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|r|p{0.5\textwidth}|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Description} \\
|
|
|
|
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_INFO\_INEXACT}} & 1 & This value is returned when
|
|
|
|
setting an option value resulted in a value being selected that does
|
|
|
|
not exactly match the requested value. For example, if a scanner
|
|
|
|
can adjust the resolution in increments of 30dpi only, setting the
|
|
|
|
resolution to 307dpi may result in an actual setting of 300dpi.
|
|
|
|
When this happens, the bitset returned in \code{*i} has this member
|
|
|
|
set. In addition, the option value is modified to reflect the
|
|
|
|
actual (rounded) value that was used by the backend. Note that
|
|
|
|
inexact values are admissible for strings as well. A backend may
|
|
|
|
choose to ``round'' a string to the closest matching legal string
|
|
|
|
for a constrained string value. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_INFO\_RELOAD\_OPTIONS}} & 2 & The setting of an
|
|
|
|
option may affect the value or availability of one or more {\em
|
|
|
|
other\/} options. When this happens, the SANE backend sets this
|
|
|
|
member in \code{*i} to indicate that the application should reload
|
|
|
|
all options. This member may be set if and only if at least one
|
|
|
|
option changed. \\
|
|
|
|
|
|
|
|
\code{\defn{SANE\_INFO\_RELOAD\_PARAMS}} & 4 & The setting of an option may
|
|
|
|
affect the parameter values (see \code{sane\_get\_parameters()}).
|
|
|
|
If setting an option affects the parameter values, this member will
|
|
|
|
be set in \code{*i}. Note that this member may be set even if the
|
|
|
|
parameters did not actually change. However, it is guaranteed that
|
|
|
|
the parameters never change without this member being set. \\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Additional Information Returned When Setting an Option}
|
|
|
|
\label{tab:info}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
This function may fail with one of the following status codes.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_UNSUPPORTED}:] The operation is not
|
|
|
|
supported for the specified handle and option number.
|
|
|
|
\item[\code{SANE\_STATUS\_INVAL}:] The option value is not valid.
|
|
|
|
\item[\code{SANE\_STATUS\_IO\_ERROR}:] An error occured while
|
|
|
|
communicating with the device.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_MEM}:] An insufficent amount of memory
|
|
|
|
is available.
|
|
|
|
\item[\code{SANE\_STATUS\_ACCESS\_DENIED}:] Access to the option has
|
|
|
|
been denied due to insufficient or invalid authentication.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_get\_parameters}}
|
|
|
|
|
|
|
|
This function is used to obtain the current scan parameters. The
|
|
|
|
returned parameters are guaranteed to be accurate between the time a
|
|
|
|
scan has been started (\code{sane\_start()} has been called) and the
|
|
|
|
completion of that request. Outside of that window, the returned
|
|
|
|
values are best-effort estimates of what the parameters will be when
|
|
|
|
\code{sane\_start()} gets invoked. Calling this function before a
|
|
|
|
scan has actually started allows, for example, to get an estimate of
|
|
|
|
how big the scanned image will be. The parameters passed to this
|
|
|
|
function are the handle \code{h} of the device for which the
|
|
|
|
parameters should be obtained and a pointer \code{p} to a parameter
|
|
|
|
structure. The parameter structure is described in more detail below.
|
|
|
|
|
|
|
|
\begin{quote}\index{sane\_get\_parameters}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_get_parameters (SANE_Handle h,
|
|
|
|
SANE_Parameters * p);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
The scan parameters are returned in a structure of type
|
|
|
|
\code{\defn{SANE\_Parameters}}. The C declaration of this structure
|
|
|
|
is given below.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{verbatim}
|
|
|
|
typedef struct
|
|
|
|
{
|
|
|
|
SANE_Frame format;
|
|
|
|
SANE_Bool last_frame;
|
|
|
|
SANE_Int lines;
|
|
|
|
SANE_Int depth;
|
|
|
|
SANE_Int pixels_per_line;
|
|
|
|
SANE_Int bytes_per_line;
|
|
|
|
}
|
|
|
|
SANE_Parameters;
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
Member \code{format} specifies the format of the next frame to be
|
|
|
|
returned. The possible values for type \code{\defn{SANE\_Frame}} are
|
|
|
|
described in Table~\ref{tab:frameformat}. The meaning of these
|
|
|
|
values is described in more detail in Section~\ref{sec:imageformat}.
|
|
|
|
\begin{table}[htbp]
|
|
|
|
\begin{center}
|
|
|
|
\leavevmode
|
|
|
|
\begin{tabular}{|l|r|l|}
|
|
|
|
\hline
|
|
|
|
\multicolumn{1}{|c|}{\bf Symbol} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Code} &
|
|
|
|
\multicolumn{1}{|c|}{\bf Description} \\
|
|
|
|
|
|
|
|
\hline\hline
|
|
|
|
|
|
|
|
\code{\defn{SANE\_FRAME\_GRAY}} & 0 & Band covering human visual range. \\
|
|
|
|
\code{\defn{SANE\_FRAME\_RGB}} & 1 & Pixel-interleaved red/green/blue bands. \\
|
|
|
|
\code{\defn{SANE\_FRAME\_RED}} & 2 & Red band of a red/green/blue image. \\
|
|
|
|
\code{\defn{SANE\_FRAME\_GREEN}} & 3 & Green band of a red/green/blue image. \\
|
|
|
|
\code{\defn{SANE\_FRAME\_BLUE}} & 4 & Blue band of a red/green/blue image. \\
|
|
|
|
|
|
|
|
\hline
|
|
|
|
\end{tabular}
|
|
|
|
\caption{Frame Format (\code{SANE\_Frame})}
|
|
|
|
\label{tab:frameformat}
|
|
|
|
\end{center}
|
|
|
|
\end{table}
|
|
|
|
|
|
|
|
Member \code{last\_frame} is set to \code{SANE\_TRUE} if and only if
|
|
|
|
the frame that is currently being acquired (or the frame that will be
|
|
|
|
acquired next if there is no current frame) is the last frame of a
|
|
|
|
multi frame image (e.g., the current frame is the blue component of a
|
|
|
|
red, green, blue image).
|
|
|
|
|
|
|
|
Member \code{lines} specifies how many scan lines the frame is
|
|
|
|
comprised of. If this value is -1, the number of lines is not known a
|
|
|
|
priori and the frontend should call \code{sane\_read()} until it
|
|
|
|
returns a status of \code{SANE\_STATUS\_EOF}.
|
|
|
|
|
|
|
|
Member \code{bytes\_per\_line} specifies the number of bytes that
|
|
|
|
comprise one scan line.
|
|
|
|
|
|
|
|
Member \code{depth} specifies the number of bits per sample.
|
|
|
|
|
|
|
|
Member \code{pixels\_per\_line} specifies the number of pixels that
|
|
|
|
comprise one scan line.
|
|
|
|
|
|
|
|
Assume $B$ is the number of channels in the frame, then the bit depth
|
|
|
|
$d$ (as given by member \code{depth}) and the number of pixels per
|
|
|
|
line $n$ (as given by this member \code{pixels\_per\_line}) are
|
|
|
|
related to $c$, the number of bytes per line (as given by member
|
|
|
|
\code{bytes\_per\_line}) as follows:
|
|
|
|
\[
|
|
|
|
c >= \left\{
|
|
|
|
\begin{array}{ll}
|
|
|
|
\lceil B\cdot n / 8\rceil & \mbox{if $d=1$}\\
|
|
|
|
B\cdot n \cdot \lceil (d + 7)/8 \rceil & \mbox{if $d>1$}
|
|
|
|
\end{array}
|
|
|
|
\right.
|
|
|
|
\]
|
|
|
|
Note that the number of bytes per line can be larger than the minimum
|
|
|
|
value imposed by the right side of this equation. A frontend must be
|
|
|
|
able to properly cope with such ``padded'' image formats.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_start}}
|
|
|
|
|
|
|
|
This function initiates aquisition of an image from the device
|
|
|
|
represented by handle \code{h}.
|
|
|
|
\begin{quote}\index{sane\_start}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_start (SANE_Handle h);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
This function may fail with one of the following status codes.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_CANCELLED}:] The operation was cancelled through
|
|
|
|
a call to \code{sane\_cancel}.
|
|
|
|
\item[\code{SANE\_STATUS\_DEVICE\_BUSY}:] The device is busy. The
|
|
|
|
operation should be retried later.
|
|
|
|
\item[\code{SANE\_STATUS\_JAMMED}:] The document feeder is jammed.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_DOCS}:] The document feeder is out of
|
|
|
|
documents.
|
|
|
|
\item[\code{SANE\_STATUS\_COVER\_OPEN}:] The scanner cover is open.
|
|
|
|
\item[\code{SANE\_STATUS\_IO\_ERROR}:] An error occurred while communicating
|
|
|
|
with the device.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_MEM}:] An insufficent amount of memory
|
|
|
|
is available.
|
2002-10-15 08:36:40 +00:00
|
|
|
\item[\code{SANE\_STATUS\_INVAL}:] The scan cannot be started with the current
|
|
|
|
set of options. The frontend should reload the option descriptors, as if
|
|
|
|
\code{\defn{SANE\_INFO\_RELOAD\_OPTIONS}} had been returned from a call to
|
|
|
|
\code{sane\_control\_option()}, since the device's capabilities may have
|
|
|
|
changed.
|
1999-08-09 18:06:01 +00:00
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_read}}
|
|
|
|
|
|
|
|
This function is used to read image data from the device represented
|
|
|
|
by handle \code{h}. Argument \code{buf} is a pointer to a memory area
|
|
|
|
that is at least \code{maxlen} bytes long. The number of bytes
|
|
|
|
returned is stored in \code{*len}. A backend must set this to zero
|
2001-05-09 17:58:06 +00:00
|
|
|
when a status other than \code{SANE\_STA\-TUS\_GOOD} is returned.
|
|
|
|
When the call succeeds, the number of bytes returned can be anywhere in
|
|
|
|
the range from 0 to \code{maxlen} bytes.
|
1999-08-09 18:06:01 +00:00
|
|
|
\begin{quote}\index{sane\_read}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_read (SANE_Handle h, SANE_Byte * buf,
|
|
|
|
SANE_Int maxlen, SANE_Int * len);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
If this function is called when no data is available, one of two
|
|
|
|
things may happen, depending on the I/O mode that is in effect for
|
|
|
|
handle \code{h}.
|
|
|
|
\begin{enumerate}
|
|
|
|
\item If the device is in blocking I/O mode (the default mode), the
|
|
|
|
call blocks until at least one data byte is available (or until some
|
|
|
|
error occurs).
|
|
|
|
|
|
|
|
\item If the device is in non-blocking I/O mode, the call returns
|
|
|
|
immediately with status \code{SANE\_STA\-TUS\_GOOD} and with
|
|
|
|
\code{*len} set to zero.
|
|
|
|
\end{enumerate}
|
|
|
|
The I/O mode of handle \code{h} can be set via a call to
|
|
|
|
\code{sane\_set\_io\_mode()}.
|
|
|
|
|
|
|
|
This function may fail with one of the following status codes.
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_CANCELLED}:] The operation was cancelled through
|
|
|
|
a call to \code{sane\_cancel}.
|
|
|
|
\item[\code{SANE\_STATUS\_EOF}:] No more data is available for the
|
|
|
|
current frame.
|
|
|
|
\item[\code{SANE\_STATUS\_JAMMED}:] The document feeder is jammed.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_DOCS}:] The document feeder is out of
|
|
|
|
documents.
|
|
|
|
\item[\code{SANE\_STATUS\_COVER\_OPEN}:] The scanner cover is open.
|
|
|
|
\item[\code{SANE\_STATUS\_IO\_ERROR}:] An error occurred while communicating
|
|
|
|
with the device.
|
|
|
|
\item[\code{SANE\_STATUS\_NO\_MEM}:] An insufficent amount of memory
|
|
|
|
is available.
|
|
|
|
\item[\code{SANE\_STATUS\_ACCESS\_DENIED}:] Access to the device has
|
|
|
|
been denied due to insufficient or invalid authentication.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_cancel}}
|
|
|
|
|
|
|
|
This function is used to immediately or as quickly as possible cancel
|
|
|
|
the currently pending operation of the device represented by handle
|
|
|
|
\code{h}.
|
|
|
|
\begin{quote}\index{sane\_cancel}
|
|
|
|
\begin{verbatim}
|
|
|
|
void sane_cancel (SANE_Handle h);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
This function can be called at any time (as long as handle \code{h} is
|
|
|
|
a valid handle) but usually affects long-running operations only (such
|
|
|
|
as image is acquisition). It is safe to call this function
|
|
|
|
asynchronously (e.g., from within a signal handler). It is important
|
|
|
|
to note that completion of this operaton does {\em not\/} imply that
|
|
|
|
the currently pending operation has been cancelled. It only
|
|
|
|
guarantees that cancellation has been {\em initiated}. Cancellation
|
|
|
|
completes only when the cancelled call returns (typically with a
|
|
|
|
status value of \code{SANE\_STATUS\_CANCELLED}). Since the SANE API
|
|
|
|
does not require any other operations to be re-entrant, this implies
|
|
|
|
that a frontend must {\em not\/} call any other operation until the
|
|
|
|
cancelled operation has returned.
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_set\_io\_mode}}
|
|
|
|
|
2002-10-15 08:36:40 +00:00
|
|
|
This function is used to set the I/O mode of handle \code{h}. The I/O mode
|
|
|
|
can be either blocking or non-blocking. If argument \code{m} is
|
|
|
|
\code{SANE\_TRUE}, the mode is set to non-blocking mode, otherwise it's set to
|
|
|
|
blocking mode. This function can be called only after a call to
|
|
|
|
\code{sane\_start()} has been performed.
|
1999-08-09 18:06:01 +00:00
|
|
|
\begin{quote}\index{sane\_set\_io\_mode}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_set_io_mode (SANE_Handle h, SANE_Bool m);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
By default, newly opened handles operate in blocking mode. A backend
|
|
|
|
may elect not to support non-blocking I/O mode. In such a case the
|
|
|
|
status value \code{SANE\_STATUS\_UNSUPPORTED} is returned. Blocking
|
|
|
|
I/O must be supported by all backends, so calling this function with
|
|
|
|
argument \code{m} set to \code{SANE\_FALSE} is guaranteed to complete
|
|
|
|
successfully.
|
|
|
|
|
|
|
|
This function may fail with one of the following status codes:
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_INVAL}:] No image acquisition is pending.
|
|
|
|
\item[\code{SANE\_STATUS\_UNSUPPORTED}:] The backend does not support
|
2002-10-15 08:36:40 +00:00
|
|
|
the requested I/O mode.
|
1999-08-09 18:06:01 +00:00
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_get\_select\_fd}}
|
|
|
|
|
|
|
|
This function is used to obtain a (platform-specific) file-descriptor
|
|
|
|
for handle \code{h} that is readable if and only if image data is
|
|
|
|
available (i.e., when a call to \code{sane\_read()} will return at
|
|
|
|
least one byte of data). If the call completes successfully, the
|
|
|
|
select file-descriptor is returned in \code{*fd}.
|
|
|
|
\begin{quote}\index{sane\_get\_select\_fd}
|
|
|
|
\begin{verbatim}
|
|
|
|
SANE_Status sane_get_select_fd (SANE_Handle h, SANE_Int *fd);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
This function can be called only after a call to \code{sane\_start()}
|
|
|
|
has been performed and the returned file-descriptor is guaranteed to
|
|
|
|
remain valid for the duration of the current image acquisition (i.e.,
|
|
|
|
until \code{sane\_cancel()} or \code{sane\_start()} get called again
|
|
|
|
or until \code{sane\_read()} returns with status
|
|
|
|
\code{SANE\_STA\-TUS\_EOF}). Indeed, a backend must guarantee to
|
|
|
|
close the returned select file descriptor at the point when the next
|
|
|
|
\code{sane\_read()} call would return \code{SANE\_STA\-TUS\_EOF}.
|
|
|
|
This is necessary to ensure the application can detect when this
|
|
|
|
condition occurs without actually having to call \code{sane\_read()}.
|
|
|
|
|
|
|
|
A backend may elect not to support this operation. In such a case,
|
|
|
|
the function returns with status code
|
|
|
|
\code{SANE\_STATUS\_UNSUPPORTED}.
|
|
|
|
|
|
|
|
Note that the only operation supported by the returned file-descriptor
|
|
|
|
is a host operating-system dependent test whether the file-descriptor
|
|
|
|
is readable (e.g., this test can be implemented using \code{select()}
|
|
|
|
or \code{poll()} under UNIX). If any other operation is performed on
|
|
|
|
the file descriptor, the behavior of the backend becomes
|
|
|
|
unpredictable. Once the file-descriptor signals ``readable'' status,
|
|
|
|
it will remain in that state until a call to \code{sane\_read()} is
|
|
|
|
performed. Since many input devices are very slow, support for this
|
|
|
|
operation is strongly encouraged as it permits an application to do
|
|
|
|
other work while image acquisition is in progress.
|
|
|
|
|
|
|
|
This function may fail with one of the following status codes:
|
|
|
|
\begin{quote}
|
|
|
|
\begin{description}
|
|
|
|
\item[\code{SANE\_STATUS\_INVAL}:] No image acquisition is pending.
|
|
|
|
\item[\code{SANE\_STATUS\_UNSUPPORTED}:] The backend does not support
|
|
|
|
this operation.
|
|
|
|
\end{description}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
|
|
|
|
\subsection{\code{sane\_strstatus}}
|
|
|
|
|
|
|
|
This function can be used to translate a SANE status code into a
|
|
|
|
printable string. The returned string is a single line of text that
|
|
|
|
forms a complete sentence, but without the trailing period
|
|
|
|
(full-stop). The function is guaranteed to never return \code{NULL}.
|
|
|
|
The returned pointer is valid at least until the next call to this
|
|
|
|
function is performed.
|
|
|
|
\begin{quote}\index{sane\_strstatus}
|
|
|
|
\begin{verbatim}
|
|
|
|
const SANE_String_Const sane_strstatus (SANE_Status status);
|
|
|
|
\end{verbatim}
|
|
|
|
\end{quote}
|
|
|
|
|
|
|
|
\section{Code Flow}\index{code flow}
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The code flow for the SANE API is illustrated in
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Figure~\ref{fig:flow}. Functions \code{sane\_init()} and
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\code{sane\_exit()} initialize and exit the backend, respectively.
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All other calls must be performed after initialization and before
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exiting the backend.
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\begin{figure}[htb]
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\begin{center}
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\leavevmode
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\psfig{file=figs/flow.eps,height=0.5\textheight}
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\caption{Code flow}
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\label{fig:flow}
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\end{center}
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\end{figure}
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Function \code{sane\_get\_devices()} can be called any time after
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\code{sane\_init()} has been called. It returns the list of the
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devices that are known at the time of the call. This list may change
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over time since some devices may be turned on or off or a remote host
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may boot or shutdown between different calls. It should be noted that
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this operation may be relatively slow since it requires contacting all
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configured devices (some of which may be on remote hosts). A frontend
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may therefore want to provide the ability for a user to directly
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select a desired device without requiring a call to this function.
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Once a device has been chosen, it is opened using a call to
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\code{sane\_open()}. Multiple devices can be open at any given time.
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A SANE backend must not impose artificial constraints on how many
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devices can be open at any given time.
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An opened device can be setup through the corresponding device handle
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using functions \code{sane\_get\_opt\-ion\_desc\-riptor()} and
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\code{sane\_control\_option()}. While setting up a device, obtaining
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option descriptors and setting and reading of option values can be
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mixed freely. It is typical for a frontend to read out all available
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options at the beginning and then build a dialog (either graphical or
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a command-line oriented option list) that allows to control the
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available options. It should be noted that the number of options is
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fixed for a given handle. However, as options are set, other options
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may become active or inactive. Thus, after setting an option, it
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maybe necessary to re-read some or all option descriptors. While
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setting up the device, it is also admissible to call
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\code{sane\_get\_parameters()} to get an estimate of what the image
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parameters will look like once image acquisition begins.
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The device handle can be put in blocking or non-blocking mode by a
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call to \code{sane\_set\_io\_mode()}. Devices are required to support
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blocking mode (which is the default mode), but support for
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non-blocking I/O is strongly encouraged for operating systems such as
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UNIX.
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After the device is setup properly, image acquisition can be started
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by a call to \code{sane\_start()}. The backend calculates the exact
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image parameters at this point. So future calls to
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\code{sane\_get\_parameters()} will return the exact values, rather
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than estimates. Whether the physical image acquisition starts at this
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point or during the first call to \code{sane\_read()} is unspecified
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by the SANE API. If non-blocking I/O and/or a select-style interface
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is desired, the frontend may attempt to call
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\code{sane\_set\_io\_mode()} and/or \code{sane\_get\_select\_fd()} at
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this point. Either of these functions may fail if the backend does
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not support the requested operation.
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Image data is collected by repeatedly calling \code{sane\_read()}.
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Eventually, this function will return an end-of-file status
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(\code{SANE\_STATUS\_EOF}). This indicates the end of the current
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frame. If the frontend expects additional frames (e.g., the
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individual channels in of a red/green/blue image or multiple images),
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it can call \code{sane\_start()} again. Once all desired frames have
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been acquired, function \code{sane\_cancel()} must be called. This
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operation can also be called at any other time to cancel a pending
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operation. Note that \code{sane\_cancel()} must be called even if the
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last read operation returned \code{SANE\_STATUS\_EOF}.
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When done using the device, the handle should be closed by a call to
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\code{sane\_close()}. Finally, before exiting the application,
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function \code{sane\_exit()} must be called. It is important not to
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forget to call this function since otherwise some resources (e.g.,
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temporary files or locks) may remain unclaimed.
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\section{Well-Known Options}\index{well-known options}
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While most backend options are completely self-describing, there are a
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cases where a user interface might want to special-case the handling
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of certain options. For example, the scan area is typically defined
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by four options that specify the top-left and bottom-right corners of
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the area. With a graphical user interface, it would be tedious to
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force the user to type in these four numbers. Instead, most such
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interfaces will want to present to the user a preview (low-resolution
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scan) of the scanner surface and let the user pick the scan area by
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dragging a rectangle into the desired position. For this reason, the
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SANE API specifies a small number of option names that have
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well-defined meanings.
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\subsection{Option Number Count}\index{option count}
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Option number 0 has an empty string as its name. The value of this
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option is of type \code{SANE\_TYPE\_INT} and it specifies the total
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number of options available for a given device (the count includes
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option number 0). This means that there are two ways of counting the
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number of options available: a frontend can either cycle through all
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option numbers starting at one until
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\code{sane\_get\_option\_descriptor()} returns \code{NULL}, or a
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frontend can directly read out the value of option number 0.
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\subsection{Scan Resolution Option}\index{scan resolution}\index{resolution option}
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Option \code{resolution} is used to select the resolution at which an
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image should be acquired. The type of this option is either
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\code{SANE\_TYPE\_INT} or \code{SANE\_TYPE\_FIXED}. The unit is
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\code{SANE\_UNIT\_DPI} (dots/inch).
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This option is not mandatory, but if a backend does support it, it
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must implement it in a manner consistent with the above definition.
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\subsection{Preview Mode Option}\index{preview mode}
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The boolean option \code{preview} is used by a frontend to inform the
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backend when image acquisition should be optimized for speed, rather
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than quality (``preview mode''). When set to \code{SANE\_TRUE},
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preview mode is in effect, when set to \code{SANE\_FALSE} image
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acquisition should proceed in normal quality mode. The setting of
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this option \emph{must not\/} affect any other option. That is, as
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far as the other options are concerned, the preview mode is completely
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side effect free. A backend can assume that the frontend will take
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care of appropriately setting the scan resolution for preview mode
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(through option \code{resolution}). A backend is free to override the
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\code{resolution} value with its own choice for preview mode, but it
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is advised to leave this choice to the frontend wherever possible.
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This option is not mandatory, but if a backend does support it, it
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must implement it in a manner consistent with the above definition.
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\subsection{Scan Area Options}\index{scan area options}
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The four most important well-known options are the ones that define
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the scan area. The scan area is defined by two points (x/y coordinate
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pairs) that specify the top-left and the bottom-right corners. This
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is illustrated in Figure~\ref{fig:area}. Note that the origin of the
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coordinate system is at the top-left corner of the scan surface as
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seen by the sensor (which typically is a mirror image of the scan
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surface seen by the user). For this reason, the top-left corner is
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the corner for which the abscissa and ordinate values are
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simultaneously the {\em smallest} and the bottom-right corner is the
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corner for which the abscissa and ordinate values are simulatenously
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the {\em largest}. If this coordinate system is not natural for a
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given device, it is the job of the backend to perform the necessary
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conversions.
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\begin{figure}[tbp]
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\begin{center}
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\leavevmode
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\psfig{file=figs/area.eps,height=0.3\textheight}
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\caption{Scan area options}
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\label{fig:area}
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\end{center}
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\end{figure}
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The names of the four options that define the scan area are given in
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the table below:
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\begin{center}
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\begin{tabular}{ll}
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{\bf Name} & {\bf Description} \\
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\code{\defn{tl-x}} & Top-left $x$ coordinate value \\
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\code{\defn{tl-y}} & Top-left $y$ coordinate value \\
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\code{\defn{br-x}} & Bottom-right $x$ coordinate value \\
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\code{\defn{br-y}} & Bottom-right $y$ coordinate value \\
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\end{tabular}
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\end{center}
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There are several rules that should be followed by front and backends
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regarding these options:
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\begin{itemize}
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\item Backends must attach a unit of either pixels
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(\code{SANE\_UNIT\_PIXEL}) or millimeters (\code{SANE\_UNIT\_MM}) to
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these options. The unit of all four options must be identical.
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\item Whenever meaningful, a backend should attach a range or a
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word-list constraint to these options.
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\item A frontend can determine the size of the scan surface by first
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checking that the options have range constraints associated. If a
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range or word-list constraints exist, the frontend can take the
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minimum and maximum values of one of the x and y option
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range-constraints to determine the scan surface size.
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\item A frontend must work properly with any or all of these options
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missing.
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\end{itemize}
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\input{net.tex}
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\chapter{Contact Information}\label{chap:contact}
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The SANE standard is discussed and evolved via a mailing list.
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Anybody with email access to the Internet can automatically join and
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leave the discussion group by sending mail to the following address.
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\begin{quote}\index{mailing list}
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\begin{verbatim}
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2003-09-24 14:59:36 +00:00
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sane-devel-request@lists.alioth.debian.org
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1999-08-09 18:06:01 +00:00
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\end{verbatim}
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\end{quote}
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To subscribe, send a mail with the body ``\verb|subscribe sane-devel|'' to the
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above address.
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A complete list of commands supported can be obtained by sending a
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mail with a subject of ``\code{help}'' to the above address. The
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mailing list is archived and available through the SANE home page at
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URL:
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\begin{quote}
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2003-09-24 14:59:36 +00:00
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\url{http://www.sane-project.org/}
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1999-08-09 18:06:01 +00:00
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\end{quote}
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\newpage
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\input{sane.ind}
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\end{document}
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