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# sane-test.5

    sane-test(5)             SANE Scanner Access Now Easy             sane-test(5)

## NAME

           sane-test - SANE backend for testing frontends

## DESCRIPTION

           The sane-test library implements a SANE (Scanner Access Now Easy) back-
           end that allows testing the SANE installation and SANE  frontends.   It
           provides  access  to  a  (nearly)  unlimited number of virtual devices.
           There is no support for real scanners or cameras.  However, the backend
           simulates scanning and setting options.

           The  idea  is  not  only to find bugs in frontends but also to show all
           capabilities of SANE.  Therefore  sane-test  implements  functions  and
           options that are not (or seldomly) found in other backends.

           The  backend  is  commented  out  in /usr/local/etc/sane.d/dll.conf, so
           either the comment character must be removed or  the  backend  must  be
           called explicitely.  E.g.  `scanimage -d test' or `xscanimage test'.

## SCAN MODE OPTIONS

           Option mode selects the scan mode (Gray or Color).

           Option  depth  determines  the number of bits per sample (1. 8, or 16).
           Keep in mind, that this value refers to the sample, not the pixel.   So
           depth=16  results  in  48  bits per pixel in color mode. The most usual
           combinations are mode=Gray, depth=1 for lineart, mode=Gray, depth=8 for
           gray  and mode=Color, depth=8 for color mode.  The combination of color
           and 1-bit mode is quite obscure (8 colors)  but  allowed  in  the  SANE
           standard.  However,  the  meaning of bits is not defined. Currently 1 =
           high intensity and 0 = low intensity is used.

           Setting option hand-scanner results in the test-backend behaving like a
           hand-scanner.   Hand-scanners  do  not  know the image height a priori.
           Instead, they return a height of -1.  Setting  this  option  allows  to
           test  whether  a  frontend can handle this correctly.  This option also
           enables a fixed width of 11 cm.

           Setting option three-pass simulates a three-pass scanner.  Older  color
           scanners  needed  to  scan the image once per color (reg/green/blue) to
           get the full image.  Therefore, in this mode three  single  frames  are
           transmitted in color mode.

           Option  three-pass-order provides support for changing the order of the
           three frames (see option three-pass above).  A frontend should  support
           all orders.

           Option resolution sets the resolution of the image in dots per inch.

## SPECIAL OPTIONS

           Option  test-picture  allows  to  set  the image that's returned to the
           frontend.  While "Solid white" and "Solid black" are quite obvious, the
           other  options  need some more explanation.  Color patterns are used to
           determine if all modes and their colors are reprented correctly by  the
           frontend.  The grid should look like the same in every mode and resolu-
           tion.   A  table  of  all  the  test  pictures   can   be   found   at:
           http://www.meier-geinitz.de/sane/test-backend/test-pictures.html.

           If  option  invert-endianess is set, the upper and lower bytes of image
           data in 16 bit modes are exchanged.  This option can be  used  to  test
           the  16  bit  modes of frontends, e.g. if the frontend uses the correct
           endianess.

           If option read-limit is set, the maximum amount of data tranferred with
           each call to sane_read() is limited.

           Option  read-limit-size  sets  the  limit for option read-limit.  A low
           limit slows down scanning.  It can be used to detect errors in frontend
           that  occur  because  of wrong assumptions on the size of the buffer or
           timing problems.

           Option read-delay enables delaying data to the frontend.

           Option read-delay-duration selects the number of microseconds the back-
           ends  waits  after each transfer of a buffer.  This option is useful to
           find timing-related bugs, especially if used over the network.

           If option read-return-value is different from "Default",  the  selected
           status  will  be returned by every call to sane_read().  This is useful
           to test the frontend's handling of the SANE statii.

           If option ppl-loss is different from 0, it  determines  the  number  of
           pixels  that are "lost" at the end of each line.  That means, lines are
           padded with unused data.

           Option fuzzy-parameters selects that  fuzzy  (inexact)  parameters  are
           returned  as  long as the scan hasn't been started.  This option can be
           used to test if the frontend uses the  parameters  it  got  before  the
           start of the scan (which it shouldn't).

           Option  non-blocking  determines  if  non-blocking  IO  for sane_read()
           should be used if supported by the frontend.

           If option select-fd is set, the backend offers a select  filedescriptor
           for detecting if sane_read() will return data.

           If  option enable-test-options is set, a fairly big list of options for
           testing the various SANE option types is enabled.

           Option print-options can be used to print a  list  of  all  options  to
           standard error.

## GEOMETRY OPTIONS

           Option tl-x determines the top-left x position of the scan area.

           Option tl-y determines the top-left y position of the scan area.

           Option br-x determines the bottom-right x position of the scan area.

           Option br-y determines the bottom-right y position of the scan area.

## BOOL TEST OPTIONS

           There  are  6  bool  test  options  in total.  Each option is numbered.
           (3/6) means: this is option 3 of 6.  The numbering scheme is  inetended
           for  easier detection of options not displayed by the frontend (bevause
           of missing support or bugs).

           Option bool-soft-select-soft-detect (1/6) is a bool  test  option  that
           has  soft  select  and soft detect (and advanced) capabilities.  That's
           just a normal bool option.

           Option bool-hard-select-soft-detect (2/6) is a bool  test  option  that
           has  hard  select  and  soft  detect (and advanced) capabilities.  That
           means the option can't be set by the frontend but by the user (e.g.  by
           pressing a button at the device).

           Option  bool-hard-select  (3/6)  is  a  bool  test option that has hard
           select (and advanced) capabilities.  That means the option can't be set
           by  the  frontend  but  by  the  user (e.g. by pressing a button at the
           device) and can't be read by the frontend.

           Option bool-soft-detect (4/6) is a  bool  test  option  that  has  soft
           detect  (and  advanced)  capabilities.   That means the option is read-
           only.

           Option  bool-soft-select-soft-detect-emulated  (5/6)  is  a  Bool  test
           option  that  has soft select, soft detect, and emulated (and advanced)
           capabilities.

           Option bool-soft-select-soft-detect-auto (6/6) is a  Bool  test  option
           that  has  soft select, soft detect, and automatic (and advanced) capa-
           bilities.  This option can be automatically set by the backend.

## INT TEST OPTIONS

           There are 6 int test options in total.

           Option int (1/6) is an int test option with no unit and  no  constraint
           set.

           Option int-constraint-range (2/6) is an int test option with unit pixel
           and constraint range set.  Minimum is 4, maximum 192, and quant is 2.

           Option int-constraint-word-list (3/6) is an int test option  with  unit
           bits and constraint word list set.

           Option  int-constraint-array  (4/6)  is an int test option with unit mm
           and using an array without constraints.

           Option  int-constraint-array-constraint-range  (5/6)  is  an  int  test
           option  with unit mm and using an array with a range constraint.  Mini-
           mum is 4, maximum 192, and quant is 2.

           Option int-constraint-array-constraint-word-list (6/6) is an  int  test
           option with unit percent and using an array a word list constraint.

## FIXED TEST OPTIONS

           There are 3 fixed test options in total.

           Option  fixed  (1/3)  is  a  fixed test option with no unit and no con-
           straint set.

           Option fixed-constraint-range (2/3) is a fixed test  option  with  unit
           microsecond  and  constraint  range  set.  Minimum  is  -42.17, maximum
           32767.9999, and quant is 2.0.

           Option fixed-constraint-word-list (3/3) is a Fixed test option with  no
           unit and constraint word list set.

## STRING TEST OPTIONS

           There are 3 string test options in total.

           Option string (1/3) is a string test option without constraint.

           Option string-constraint-string-list (2/3) is a string test option with
           string list constraint.

           Option string-constraint-long-string-list (3/3) is a string test option
           with string list constraint. Contains some more entries...

## BUTTON TEST OPTION

           Option button (1/1) is a Button test option. Prints some text...

## FILES

           /usr/local/etc/sane.d/test.conf
                  The   backend   configuration  file  (see  also  description  of
                  SANE_CONFIG_DIR below). The initial values of most of the  basic
                  SANE options can be configured in this file. A template contain-
                  ing all the default values is provided together with this  back-
                  end.   One   of   the   more  interesting  values  may  be  num-
                  ber_of_devices.  It can be used to check the frontend's  ability
                  to  show  a  long list of devices.  The config values concerning
                  resolution and geometry can be useful to test  the  handling  of
                  big file sizes.

           /usr/local/lib/sane/libsane-test.a
                  The static library implementing this backend.

           /usr/local/lib/sane/libsane-test.so
                  The shared library implementing this backend (present on systems
                  that support dynamic loading).

## ENVIRONMENT

           SANE_CONFIG_DIR
                  This environment variable specifies the list of directories that
                  may contain the configuration file.  Under UNIX, the directories
                  are separated by a colon (`:'), under OS/2, they  are  separated
                  by a semi-colon (`;').  If this variable is not set, the config-
                  uration file is searched in two default directories: first,  the
                  current     working     directory     (".")    and    then    in
                  /usr/local/etc/sane.d.  If the value of the environment variable
                  ends  with  the  directory separator character, then the default
                  directories are searched after the explicitly specified directo-
                  ries.   For  example,  setting SANE_CONFIG_DIR to "/tmp/config:"
                  would   result   in   directories   "tmp/config",    ".",    and
                  "/usr/local/etc/sane.d" being searched (in this order).

           SANE_DEBUG_TEST
                  If  the  library  was  compiled with debug support enabled, this
                  environment variable controls the debug level for this  backend.
                  Higher debug levels increase the verbosity of the output.

                  Example: export SANE_DEBUG_TEST=4

## SEE ALSO

           sane(7), http://www.meier-geinitz.de/sane/test-backend/

## AUTHOR

           Henning Meier-Geinitz <henning@meier-geinitz.de>

## BUGS

           - config file values aren't tested for correctness

    sane-backends 1.0.12-cvs          24 Jul 2002                     sane-test(5)