kopia lustrzana https://gitlab.com/sane-project/backends
164 wiersze
4.7 KiB
C
164 wiersze
4.7 KiB
C
#include "escl.h"
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#include "../include/sane/sanei.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#if(defined HAVE_LIBPNG)
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#include <png.h>
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#endif
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#include <setjmp.h>
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#if(defined HAVE_LIBPNG)
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/**
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* \fn SANE_Status escl_sane_decompressor(escl_sane_t *handler)
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* \brief Function that aims to decompress the png image to SANE be able to read the image.
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* This function is called in the "sane_read" function.
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*
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* \return SANE_STATUS_GOOD (if everything is OK, otherwise, SANE_STATUS_NO_MEM/SANE_STATUS_INVAL)
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*/
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SANE_Status
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get_PNG_data(capabilities_t *scanner, int *w, int *h, int *components)
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{
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unsigned int width = 0; /* largeur */
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unsigned int height = 0; /* hauteur */
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int bps = 3; /* composantes d'un texel */
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unsigned char *texels = NULL; /* données de l'image */
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unsigned int i = 0;
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png_byte magic[8];
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// read magic number
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fread (magic, 1, sizeof (magic), scanner->tmp);
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// check for valid magic number
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if (!png_check_sig (magic, sizeof (magic)))
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{
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fprintf(stderr,"PNG error: is not a valid PNG image!\n");
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if (scanner->tmp) {
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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}
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return (SANE_STATUS_INVAL);
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}
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// create a png read struct
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png_structp png_ptr = png_create_read_struct
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(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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if (!png_ptr)
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{
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if (scanner->tmp) {
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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}
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return (SANE_STATUS_INVAL);
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}
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// create a png info struct
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png_infop info_ptr = png_create_info_struct (png_ptr);
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if (!info_ptr)
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{
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png_destroy_read_struct (&png_ptr, NULL, NULL);
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if (scanner->tmp) {
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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}
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return (SANE_STATUS_INVAL);
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}
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// initialize the setjmp for returning properly after a libpng
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// error occured
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if (setjmp (png_jmpbuf (png_ptr)))
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{
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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if (texels)
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free (texels);
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fprintf(stderr,"PNG read error.\n");
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if (scanner->tmp) {
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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}
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return (SANE_STATUS_INVAL);
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}
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// setup libpng for using standard C fread() function
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// with our FILE pointer
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png_init_io (png_ptr, scanner->tmp);
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// tell libpng that we have already read the magic number
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png_set_sig_bytes (png_ptr, sizeof (magic));
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// read png info
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png_read_info (png_ptr, info_ptr);
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int bit_depth, color_type;
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// get some usefull information from header
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bit_depth = png_get_bit_depth (png_ptr, info_ptr);
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color_type = png_get_color_type (png_ptr, info_ptr);
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// convert index color images to RGB images
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if (color_type == PNG_COLOR_TYPE_PALETTE)
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png_set_palette_to_rgb (png_ptr);
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else if (color_type != PNG_COLOR_TYPE_RGB && color_type != PNG_COLOR_TYPE_RGB_ALPHA)
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{
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fprintf(stderr,"PNG format not supported.\n");
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if (scanner->tmp) {
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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}
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return (SANE_STATUS_INVAL);
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}
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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bps = 4;
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else
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bps = 3;
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if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
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png_set_tRNS_to_alpha (png_ptr);
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if (bit_depth == 16)
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png_set_strip_16 (png_ptr);
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else if (bit_depth < 8)
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png_set_packing (png_ptr);
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// update info structure to apply transformations
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png_read_update_info (png_ptr, info_ptr);
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// retrieve updated information
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png_get_IHDR (png_ptr, info_ptr,
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(png_uint_32*)(&width),
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(png_uint_32*)(&height),
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&bit_depth, &color_type,
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NULL, NULL, NULL);
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*w = (int)width;
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*h = (int)height;
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*components = bps;
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// we can now allocate memory for storing pixel data
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texels = (unsigned char *)malloc (sizeof (unsigned char) * width
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* height * bps);
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png_bytep *row_pointers;
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// setup a pointer array. Each one points at the begening of a row.
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row_pointers = (png_bytep *)malloc (sizeof (png_bytep) * height);
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for (i = 0; i < height; ++i)
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{
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row_pointers[i] = (png_bytep)(texels +
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((height - (i + 1)) * width * bps));
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}
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// read pixel data using row pointers
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png_read_image (png_ptr, row_pointers);
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// we don't need row pointers anymore
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scanner->img_data = texels;
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scanner->img_size = (int)(width * height * bps);
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scanner->img_read = 0;
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free (row_pointers);
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fclose(scanner->tmp);
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scanner->tmp = NULL;
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return (SANE_STATUS_GOOD);
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}
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#else
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SANE_Status
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get_PNG_data(capabilities_t __sane_unused__ *scanner,
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int __sane_unused__ *w,
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int __sane_unused__ *h,
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int __sane_unused__ *bps)
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{
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return (SANE_STATUS_INVAL);
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}
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#endif
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