chromium/third_party/libjpeg_turbo/rdbmp.c

/*
 * rdbmp.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2009-2017 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Modified 2011 by Siarhei Siamashka.
 * Copyright (C) 2015, 2017-2018, 2021-2022, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains routines to read input images in Microsoft "BMP"
 * format (MS Windows 3.x, OS/2 1.x, and OS/2 2.x flavors).
 * Currently, only 8-, 24-, and 32-bit images are supported, not 1-bit or
 * 4-bit (feeding such low-depth images into JPEG would be silly anyway).
 * Also, we don't support RLE-compressed files.
 *
 * These routines may need modification for non-Unix environments or
 * specialized applications.  As they stand, they assume input from
 * an ordinary stdio stream.  They further assume that reading begins
 * at the start of the file; start_input may need work if the
 * user interface has already read some data (e.g., to determine that
 * the file is indeed BMP format).
 *
 * This code contributed by James Arthur Boucher.
 */

#include "cmyk.h"
#include "cdjpeg.h"             /* Common decls for cjpeg/djpeg applications */

#ifdef BMP_SUPPORTED


/* Macros to deal with unsigned chars as efficiently as compiler allows */

U_CHAR;
#define UCH(x) …


#define ReadOK(file, buffer, len) …

static int alpha_index[JPEG_NUMCS] = …;


/* Private version of data source object */

bmp_source_ptr;

bmp_source_struct;


LOCAL(int)
read_byte(bmp_source_ptr sinfo)
/* Read next byte from BMP file */
{ … }


LOCAL(void)
read_colormap(bmp_source_ptr sinfo, int cmaplen, int mapentrysize)
/* Read the colormap from a BMP file */
{ … }


/*
 * Read one row of pixels.
 * The image has been read into the whole_image array, but is otherwise
 * unprocessed.  We must read it out in top-to-bottom row order, and if
 * it is an 8-bit image, we must expand colormapped pixels to 24bit format.
 */

METHODDEF(JDIMENSION)
get_8bit_row(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 8-bit colormap indexes */
{ … }


METHODDEF(JDIMENSION)
get_24bit_row(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 24-bit pixels */
{ … }


METHODDEF(JDIMENSION)
get_32bit_row(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
/* This version is for reading 32-bit pixels */
{ … }


/*
 * This method loads the image into whole_image during the first call on
 * get_pixel_rows.  The get_pixel_rows pointer is then adjusted to call
 * get_8bit_row, get_24bit_row, or get_32bit_row on subsequent calls.
 */

METHODDEF(JDIMENSION)
preload_image(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{ … }


/*
 * Read the file header; return image size and component count.
 */

METHODDEF(void)
start_input_bmp(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{ … }


/*
 * Finish up at the end of the file.
 */

METHODDEF(void)
finish_input_bmp(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{ … }


/*
 * The module selection routine for BMP format input.
 */

GLOBAL(cjpeg_source_ptr)
jinit_read_bmp(j_compress_ptr cinfo, boolean use_inversion_array)
{ … }

#endif /* BMP_SUPPORTED */