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bmp.c
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bmp.c
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#define IMAGER_NO_CONTEXT
#include <stdarg.h>
#include "imageri.h"
/*
=head1 NAME
bmp.c - read and write windows BMP files
=head1 SYNOPSIS
i_img *im;
io_glue *ig;
if (!i_writebmp_wiol(im, ig)) {
... error ...
}
im = i_readbmp(ig);
=head1 DESCRIPTION
Reads and writes Windows BMP files.
=over
=cut
*/
#define FILEHEAD_SIZE 14
#define INFOHEAD_SIZE 40
#define BI_RGB 0
#define BI_RLE8 1
#define BI_RLE4 2
#define BI_BITFIELDS 3
#define BMPRLE_ENDOFLINE 0
#define BMPRLE_ENDOFBMP 1
#define BMPRLE_DELTA 2
#define SIGNBIT32 ((i_upacked_t)1U << 31)
#define SIGNBIT16 ((i_upacked_t)1U << 15)
#define SIGNMAX32 ((1UL << 31) - 1)
static int read_packed(io_glue *ig, char *format, ...);
static int write_packed(io_glue *ig, char *format, ...);
static int write_bmphead(io_glue *ig, i_img *im, int bit_count,
int data_size);
static int write_1bit_data(io_glue *ig, i_img *im);
static int write_4bit_data(io_glue *ig, i_img *im);
static int write_8bit_data(io_glue *ig, i_img *im);
static int write_24bit_data(io_glue *ig, i_img *im);
static int read_bmp_pal(io_glue *ig, i_img *im, int count);
static i_img *read_1bit_bmp(io_glue *ig, int xsize, int ysize, int clr_used,
int compression, long offbits, int allow_incomplete);
static i_img *read_4bit_bmp(io_glue *ig, int xsize, int ysize, int clr_used,
int compression, long offbits, int allow_incomplete);
static i_img *read_8bit_bmp(io_glue *ig, int xsize, int ysize, int clr_used,
int compression, long offbits, int allow_incomplete);
static i_img *read_direct_bmp(io_glue *ig, int xsize, int ysize,
int bit_count, int clr_used, int compression,
long offbits, int allow_incomplete);
/* used for the read_packed() and write_packed() functions, an integer
* type */
typedef long i_packed_t;
typedef unsigned long i_upacked_t;
/*
=item i_writebmp_wiol(im, io_glue)
Writes the image as a BMP file. Uses 1-bit, 4-bit, 8-bit or 24-bit
formats depending on the image.
Never compresses the image.
=cut
*/
int
i_writebmp_wiol(i_img *im, io_glue *ig) {
dIMCTXim(im);
i_clear_error();
/* pick a format */
if (im->type == i_direct_type) {
return write_24bit_data(ig, im);
}
else {
int pal_size;
/* must be paletted */
pal_size = i_colorcount(im);
if (pal_size <= 2) {
return write_1bit_data(ig, im);
}
else if (pal_size <= 16) {
return write_4bit_data(ig, im);
}
else {
return write_8bit_data(ig, im);
}
}
}
/*
=item i_readbmp_wiol(ig)
Reads a Windows format bitmap from the given file.
Handles BI_RLE4 and BI_RLE8 compressed images. Attempts to handle
BI_BITFIELDS images too, but I need a test image.
=cut
*/
i_img *
i_readbmp_wiol(io_glue *ig, int allow_incomplete) {
i_packed_t b_magic, m_magic, filesize, res1, res2, infohead_size;
i_packed_t xsize, ysize, planes, bit_count, compression, size_image, xres, yres;
i_packed_t clr_used, clr_important, offbits;
i_img *im;
dIMCTXio(ig);
im_log((aIMCTX, 1, "i_readbmp_wiol(ig %p)\n", ig));
i_clear_error();
if (!read_packed(ig, "CCVvvVVV!V!vvVVVVVV", &b_magic, &m_magic, &filesize,
&res1, &res2, &offbits, &infohead_size,
&xsize, &ysize, &planes,
&bit_count, &compression, &size_image, &xres, &yres,
&clr_used, &clr_important)) {
i_push_error(0, "file too short to be a BMP file");
return 0;
}
if (b_magic != 'B' || m_magic != 'M' || infohead_size != INFOHEAD_SIZE
|| planes != 1) {
i_push_error(0, "not a BMP file");
return 0;
}
im_log((aIMCTX, 1, " bmp header: filesize %d offbits %d xsize %d ysize %d planes %d "
"bit_count %d compression %d size %d xres %d yres %d clr_used %d "
"clr_important %d\n", (int)filesize, (int)offbits, (int)xsize,
(int)ysize, (int)planes, (int)bit_count, (int)compression,
(int)size_image, (int)xres, (int)yres, (int)clr_used,
(int)clr_important));
if (!i_int_check_image_file_limits(xsize, abs((int)ysize), 3, sizeof(i_sample_t))) {
im_log((aIMCTX, 1, "i_readbmp_wiol: image size exceeds limits\n"));
return NULL;
}
switch (bit_count) {
case 1:
im = read_1bit_bmp(ig, xsize, ysize, clr_used, compression, offbits,
allow_incomplete);
break;
case 4:
im = read_4bit_bmp(ig, xsize, ysize, clr_used, compression, offbits,
allow_incomplete);
break;
case 8:
im = read_8bit_bmp(ig, xsize, ysize, clr_used, compression, offbits,
allow_incomplete);
break;
case 32:
case 24:
case 16:
im = read_direct_bmp(ig, xsize, ysize, bit_count, clr_used, compression,
offbits, allow_incomplete);
break;
default:
im_push_errorf(aIMCTX, 0, "unknown bit count for BMP file (%d)", (int)bit_count);
return NULL;
}
if (im) {
/* store the resolution */
if (xres && !yres)
yres = xres;
else if (yres && !xres)
xres = yres;
if (xres) {
i_tags_set_float2(&im->tags, "i_xres", 0, xres * 0.0254, 4);
i_tags_set_float2(&im->tags, "i_yres", 0, yres * 0.0254, 4);
}
i_tags_addn(&im->tags, "bmp_compression", 0, compression);
i_tags_addn(&im->tags, "bmp_important_colors", 0, clr_important);
i_tags_addn(&im->tags, "bmp_used_colors", 0, clr_used);
i_tags_addn(&im->tags, "bmp_filesize", 0, filesize);
i_tags_addn(&im->tags, "bmp_bit_count", 0, bit_count);
i_tags_add(&im->tags, "i_format", 0, "bmp", 3, 0);
}
return im;
}
/*
=back
=head1 IMPLEMENTATION FUNCTIONS
Internal functions used in the implementation.
=over
=item read_packed(ig, format, ...)
Reads from the specified "file" the specified sizes. The format codes
match those used by perl's pack() function, though only a few are
implemented. In all cases the vararg arguement is an int *.
Returns non-zero if all of the arguments were read.
=cut
*/
static int
read_packed(io_glue *ig, char *format, ...) {
unsigned char buf[4];
va_list ap;
i_packed_t *p;
i_packed_t work;
int code;
int shrieking; /* format code has a ! flag */
va_start(ap, format);
while (*format) {
p = va_arg(ap, i_packed_t *);
code = *format++;
shrieking = *format == '!';
if (shrieking) ++format;
switch (code) {
case 'v':
if (i_io_read(ig, buf, 2) != 2)
goto fail;
work = buf[0] + ((i_packed_t)buf[1] << 8);
if (shrieking)
*p = (work ^ SIGNBIT16) - SIGNBIT16;
else
*p = work;
break;
case 'V':
if (i_io_read(ig, buf, 4) != 4)
goto fail;
work = buf[0] + (buf[1] << 8) + ((i_packed_t)buf[2] << 16) + ((i_packed_t)buf[3] << 24);
if (shrieking)
*p = (work ^ SIGNBIT32) - SIGNBIT32;
else
*p = work;
break;
case 'C':
if (i_io_read(ig, buf, 1) != 1)
goto fail;
*p = buf[0];
break;
case 'c':
if (i_io_read(ig, buf, 1) != 1)
goto fail;
*p = (char)buf[0];
break;
case '3': /* extension - 24-bit number */
if (i_io_read(ig, buf, 3) != 3)
goto fail;
*p = buf[0] + (buf[1] << 8) + ((i_packed_t)buf[2] << 16);
break;
default:
{
dIMCTXio(ig);
im_fatal(aIMCTX, 1, "Unknown read_packed format code 0x%02x", code);
}
}
}
va_end(ap);
return 1;
fail:
va_end(ap);
return 0;
}
/*
=item write_packed(ig, format, ...)
Writes packed data to the specified io_glue.
Returns non-zero on success.
=cut
*/
static int
write_packed(io_glue *ig, char *format, ...) {
unsigned char buf[4];
va_list ap;
int i;
va_start(ap, format);
while (*format) {
i = va_arg(ap, i_upacked_t);
switch (*format) {
case 'v':
buf[0] = i & 255;
buf[1] = i / 256;
if (i_io_write(ig, buf, 2) == -1)
goto fail;
break;
case 'V':
buf[0] = i & 0xFF;
buf[1] = (i >> 8) & 0xFF;
buf[2] = (i >> 16) & 0xFF;
buf[3] = (i >> 24) & 0xFF;
if (i_io_write(ig, buf, 4) == -1)
goto fail;
break;
case 'C':
case 'c':
buf[0] = i & 0xFF;
if (i_io_write(ig, buf, 1) == -1)
goto fail;
break;
default:
{
dIMCTXio(ig);
im_fatal(aIMCTX, 1, "Unknown write_packed format code 0x%02x", *format);
}
}
++format;
}
va_end(ap);
return 1;
fail:
va_end(ap);
return 0;
}
/*
=item write_bmphead(ig, im, bit_count, data_size)
Writes a Windows BMP header to the file.
Returns non-zero on success.
=cut
*/
static
int write_bmphead(io_glue *ig, i_img *im, int bit_count, int data_size) {
double xres, yres;
int got_xres, got_yres, aspect_only;
int colors_used = 0;
int offset = FILEHEAD_SIZE + INFOHEAD_SIZE;
dIMCTXim(im);
if (im->xsize > SIGNMAX32 || im->ysize > SIGNMAX32) {
i_push_error(0, "image too large to write to BMP");
return 0;
}
got_xres = i_tags_get_float(&im->tags, "i_xres", 0, &xres);
got_yres = i_tags_get_float(&im->tags, "i_yres", 0, &yres);
if (!i_tags_get_int(&im->tags, "i_aspect_only", 0,&aspect_only))
aspect_only = 0;
if (!got_xres) {
if (!got_yres)
xres = yres = 72;
else
xres = yres;
}
else {
if (!got_yres)
yres = xres;
}
if (xres <= 0 || yres <= 0)
xres = yres = 72;
if (aspect_only) {
/* scale so the smaller value is 72 */
double ratio;
if (xres < yres) {
ratio = 72.0 / xres;
}
else {
ratio = 72.0 / yres;
}
xres *= ratio;
yres *= ratio;
}
/* now to pels/meter */
xres *= 100.0/2.54;
yres *= 100.0/2.54;
if (im->type == i_palette_type) {
colors_used = i_colorcount(im);
offset += 4 * colors_used;
}
if (!write_packed(ig, "CCVvvVVVVvvVVVVVV", 'B', 'M',
(i_upacked_t)(data_size+offset),
(i_upacked_t)0, (i_upacked_t)0, (i_upacked_t)offset,
(i_upacked_t)INFOHEAD_SIZE, (i_upacked_t)im->xsize,
(i_upacked_t)im->ysize, (i_upacked_t)1,
(i_upacked_t)bit_count, (i_upacked_t)BI_RGB,
(i_upacked_t)data_size,
(i_upacked_t)(xres+0.5), (i_upacked_t)(yres+0.5),
(i_upacked_t)colors_used, (i_upacked_t)colors_used)){
i_push_error(0, "cannot write bmp header");
return 0;
}
if (im->type == i_palette_type) {
int i;
i_color c;
for (i = 0; i < colors_used; ++i) {
i_getcolors(im, i, &c, 1);
if (im->channels >= 3) {
if (!write_packed(ig, "CCCC", (i_upacked_t)(c.channel[2]),
(i_upacked_t)(c.channel[1]),
(i_upacked_t)(c.channel[0]), (i_upacked_t)0)) {
i_push_error(0, "cannot write palette entry");
return 0;
}
}
else {
i_upacked_t v = c.channel[0];
if (!write_packed(ig, "CCCC", v, v, v, 0)) {
i_push_error(0, "cannot write palette entry");
return 0;
}
}
}
}
return 1;
}
/*
=item write_1bit_data(ig, im)
Writes the image data as a 1-bit/pixel image.
Returns non-zero on success.
=cut
*/
static int
write_1bit_data(io_glue *ig, i_img *im) {
i_palidx *line;
unsigned char *packed;
int byte;
int mask;
unsigned char *out;
int line_size = (im->xsize+7) / 8;
int x, y;
int unpacked_size;
dIMCTXim(im);
/* round up to nearest multiple of four */
line_size = (line_size + 3) / 4 * 4;
if (!write_bmphead(ig, im, 1, line_size * im->ysize))
return 0;
/* this shouldn't be an issue, but let's be careful */
unpacked_size = im->xsize + 8;
if (unpacked_size < im->xsize) {
i_push_error(0, "integer overflow during memory allocation");
return 0;
}
line = mymalloc(unpacked_size); /* checked 29jun05 tonyc */
memset(line + im->xsize, 0, 8);
/* size allocated here is always much smaller than xsize, hence
can't overflow int */
packed = mymalloc(line_size); /* checked 29jun05 tonyc */
memset(packed, 0, line_size);
for (y = im->ysize-1; y >= 0; --y) {
i_gpal(im, 0, im->xsize, y, line);
mask = 0x80;
byte = 0;
out = packed;
for (x = 0; x < im->xsize; ++x) {
if (line[x])
byte |= mask;
if ((mask >>= 1) == 0) {
*out++ = byte;
byte = 0;
mask = 0x80;
}
}
if (mask != 0x80) {
*out++ = byte;
}
if (i_io_write(ig, packed, line_size) < 0) {
myfree(packed);
myfree(line);
i_push_error(0, "writing 1 bit/pixel packed data");
return 0;
}
}
myfree(packed);
myfree(line);
if (i_io_close(ig))
return 0;
return 1;
}
/*
=item write_4bit_data(ig, im)
Writes the image data as a 4-bit/pixel image.
Returns non-zero on success.
=cut
*/
static int
write_4bit_data(io_glue *ig, i_img *im) {
i_palidx *line;
unsigned char *packed;
unsigned char *out;
int line_size = (im->xsize+1) / 2;
int x, y;
int unpacked_size;
dIMCTXim(im);
/* round up to nearest multiple of four */
line_size = (line_size + 3) / 4 * 4;
if (!write_bmphead(ig, im, 4, line_size * im->ysize))
return 0;
/* this shouldn't be an issue, but let's be careful */
unpacked_size = im->xsize + 2;
if (unpacked_size < im->xsize) {
i_push_error(0, "integer overflow during memory allocation");
return 0;
}
line = mymalloc(unpacked_size); /* checked 29jun05 tonyc */
memset(line + im->xsize, 0, 2);
/* size allocated here is always much smaller than xsize, hence
can't overflow int */
packed = mymalloc(line_size); /* checked 29jun05 tonyc */
memset(packed, 0, line_size);
for (y = im->ysize-1; y >= 0; --y) {
i_gpal(im, 0, im->xsize, y, line);
out = packed;
for (x = 0; x < im->xsize; x += 2) {
*out++ = (line[x] << 4) + line[x+1];
}
if (i_io_write(ig, packed, line_size) < 0) {
myfree(packed);
myfree(line);
i_push_error(0, "writing 4 bit/pixel packed data");
return 0;
}
}
myfree(packed);
myfree(line);
if (i_io_close(ig))
return 0;
return 1;
}
/*
=item write_8bit_data(ig, im)
Writes the image data as a 8-bit/pixel image.
Returns non-zero on success.
=cut
*/
static int
write_8bit_data(io_glue *ig, i_img *im) {
i_palidx *line;
int line_size = im->xsize;
int y;
int unpacked_size;
dIMCTXim(im);
/* round up to nearest multiple of four */
line_size = (line_size + 3) / 4 * 4;
if (!write_bmphead(ig, im, 8, line_size * im->ysize))
return 0;
/* this shouldn't be an issue, but let's be careful */
unpacked_size = im->xsize + 4;
if (unpacked_size < im->xsize) {
i_push_error(0, "integer overflow during memory allocation");
return 0;
}
line = mymalloc(unpacked_size); /* checked 29jun05 tonyc */
memset(line + im->xsize, 0, 4);
for (y = im->ysize-1; y >= 0; --y) {
i_gpal(im, 0, im->xsize, y, line);
if (i_io_write(ig, line, line_size) < 0) {
myfree(line);
i_push_error(0, "writing 8 bit/pixel packed data");
return 0;
}
}
myfree(line);
if (i_io_close(ig))
return 0;
return 1;
}
/*
=item write_24bit_data(ig, im)
Writes the image data as a 24-bit/pixel image.
Returns non-zero on success.
=cut
*/
static int
write_24bit_data(io_glue *ig, i_img *im) {
unsigned char *samples;
int y;
int line_size = 3 * im->xsize;
i_color bg;
dIMCTXim(im);
i_get_file_background(im, &bg);
/* just in case we implement a direct format with 2bytes/pixel
(unlikely though) */
if (line_size / 3 != im->xsize) {
i_push_error(0, "integer overflow during memory allocation");
return 0;
}
line_size = (line_size + 3) / 4 * 4;
if (!write_bmphead(ig, im, 24, line_size * im->ysize))
return 0;
samples = mymalloc(4 * im->xsize);
memset(samples, 0, line_size);
for (y = im->ysize-1; y >= 0; --y) {
unsigned char *samplep = samples;
int x;
i_gsamp_bg(im, 0, im->xsize, y, samples, 3, &bg);
for (x = 0; x < im->xsize; ++x) {
unsigned char tmp = samplep[2];
samplep[2] = samplep[0];
samplep[0] = tmp;
samplep += 3;
}
if (i_io_write(ig, samples, line_size) < 0) {
i_push_error(0, "writing image data");
myfree(samples);
return 0;
}
}
myfree(samples);
if (i_io_close(ig))
return 0;
return 1;
}
/*
=item read_bmp_pal(ig, im, count)
Reads count palette entries from the file and add them to the image.
Returns non-zero on success.
=cut
*/
static int
read_bmp_pal(io_glue *ig, i_img *im, int count) {
int i;
i_packed_t r, g, b, x;
i_color c;
dIMCTXio(ig);
for (i = 0; i < count; ++i) {
if (!read_packed(ig, "CCCC", &b, &g, &r, &x)) {
i_push_error(0, "reading BMP palette");
return 0;
}
c.channel[0] = r;
c.channel[1] = g;
c.channel[2] = b;
if (i_addcolors(im, &c, 1) < 0) {
i_push_error(0, "out of space in image palette");
return 0;
}
}
return 1;
}
/*
=item read_1bit_bmp(ig, xsize, ysize, clr_used, compression, offbits)
Reads in the palette and image data for a 1-bit/pixel image.
Returns the image or NULL.
=cut
*/
static i_img *
read_1bit_bmp(io_glue *ig, int xsize, int ysize, int clr_used,
int compression, long offbits, int allow_incomplete) {
i_img *im;
int x, y, lasty, yinc, start_y;
i_palidx *line, *p;
unsigned char *packed;
int line_size = (xsize + 7)/8;
int bit;
unsigned char *in;
long base_offset;
dIMCTXio(ig);
if (compression != BI_RGB) {
im_push_errorf(aIMCTX, 0, "unknown 1-bit BMP compression (%d)", compression);
return NULL;
}
if ((i_img_dim)((i_img_dim_u)xsize + 8) < xsize) { /* if there was overflow */
/* we check with 8 because we allocate that much for the decoded
line buffer */
i_push_error(0, "integer overflow during memory allocation");
return NULL;
}
/* if xsize+7 is ok then (xsize+7)/8 will be and the minor
adjustments below won't make it overflow */
line_size = (line_size+3) / 4 * 4;
if (ysize > 0) {
start_y = ysize-1;
lasty = -1;
yinc = -1;
}
else {
/* when ysize is -ve it's a top-down image */
ysize = -ysize;
start_y = 0;
lasty = ysize;
yinc = 1;
}
y = start_y;
if (!clr_used)
clr_used = 2;
if (clr_used < 0 || clr_used > 2) {
im_push_errorf(aIMCTX, 0, "out of range colors used (%d)", clr_used);
return NULL;
}
base_offset = FILEHEAD_SIZE + INFOHEAD_SIZE + clr_used * 4;
if (offbits < base_offset) {
im_push_errorf(aIMCTX, 0, "image data offset too small (%ld)", offbits);
return NULL;
}
im = i_img_pal_new(xsize, ysize, 3, 256);
if (!im)
return NULL;
if (!read_bmp_pal(ig, im, clr_used)) {
i_img_destroy(im);
return NULL;
}
if (offbits > base_offset) {
/* this will be slow if the offset is large, but that should be
rare */
char buffer;
while (base_offset < offbits) {
if (i_io_read(ig, &buffer, 1) != 1) {
i_img_destroy(im);
i_push_error(0, "failed skipping to image data offset");
return NULL;
}
++base_offset;
}
}
i_tags_add(&im->tags, "bmp_compression_name", 0, "BI_RGB", -1, 0);
packed = mymalloc(line_size); /* checked 29jun05 tonyc */
line = mymalloc(xsize+8); /* checked 29jun05 tonyc */
while (y != lasty) {
if (i_io_read(ig, packed, line_size) != line_size) {
myfree(packed);
myfree(line);
if (allow_incomplete) {
i_tags_setn(&im->tags, "i_incomplete", 1);
i_tags_setn(&im->tags, "i_lines_read", abs(start_y - y));
return im;
}
else {
i_push_error(0, "failed reading 1-bit bmp data");
i_img_destroy(im);
return NULL;
}
}
in = packed;
bit = 0x80;
p = line;
for (x = 0; x < xsize; ++x) {
*p++ = (*in & bit) ? 1 : 0;
bit >>= 1;
if (!bit) {
++in;
bit = 0x80;
}
}
i_ppal(im, 0, xsize, y, line);
y += yinc;
}
myfree(packed);
myfree(line);
return im;
}
/*
=item read_4bit_bmp(ig, xsize, ysize, clr_used, compression)
Reads in the palette and image data for a 4-bit/pixel image.
Returns the image or NULL.
Hopefully this will be combined with the following function at some
point.
=cut
*/
static i_img *
read_4bit_bmp(io_glue *ig, int xsize, int ysize, int clr_used,
int compression, long offbits, int allow_incomplete) {
i_img *im;
int x, y, lasty, yinc;
i_palidx *line, *p;
unsigned char *packed;
int line_size = (xsize + 1)/2;
unsigned char *in;
int size, i;
long base_offset;
int starty;
dIMCTXio(ig);
/* line_size is going to be smaller than xsize in most cases (and
when it's not, xsize is itself small), and hence not overflow */
line_size = (line_size+3) / 4 * 4;
if (ysize > 0) {
starty = ysize-1;
lasty = -1;
yinc = -1;
}
else {
/* when ysize is -ve it's a top-down image */
ysize = -ysize;
starty = 0;
lasty = ysize;
yinc = 1;
}
y = starty;
if (!clr_used)
clr_used = 16;
if (clr_used > 16 || clr_used < 0) {
im_push_errorf(aIMCTX, 0, "out of range colors used (%d)", clr_used);
return NULL;
}
base_offset = FILEHEAD_SIZE + INFOHEAD_SIZE + clr_used * 4;
if (offbits < base_offset) {
im_push_errorf(aIMCTX, 0, "image data offset too small (%ld)", offbits);
return NULL;
}
im = i_img_pal_new(xsize, ysize, 3, 256);
if (!im) /* error should have been pushed already */
return NULL;
if (!read_bmp_pal(ig, im, clr_used)) {
i_img_destroy(im);
return NULL;
}
if (offbits > base_offset) {
/* this will be slow if the offset is large, but that should be
rare */
char buffer;
while (base_offset < offbits) {
if (i_io_read(ig, &buffer, 1) != 1) {
i_img_destroy(im);
i_push_error(0, "failed skipping to image data offset");
return NULL;
}
++base_offset;
}
}
if (line_size < 260)
packed = mymalloc(260); /* checked 29jun05 tonyc */
else
packed = mymalloc(line_size); /* checked 29jun05 tonyc */
/* xsize won't approach MAXINT */
line = mymalloc(xsize+1); /* checked 29jun05 tonyc */
if (compression == BI_RGB) {
i_tags_add(&im->tags, "bmp_compression_name", 0, "BI_RGB", -1, 0);
while (y != lasty) {
if (i_io_read(ig, packed, line_size) != line_size) {
myfree(packed);
myfree(line);
if (allow_incomplete) {
i_tags_setn(&im->tags, "i_incomplete", 1);
i_tags_setn(&im->tags, "i_lines_read", abs(y - starty));
return im;
}
else {
i_push_error(0, "failed reading 4-bit bmp data");
i_img_destroy(im);
return NULL;
}
}
in = packed;
p = line;
for (x = 0; x < xsize; x+=2) {
*p++ = *in >> 4;
*p++ = *in & 0x0F;
++in;
}
i_ppal(im, 0, xsize, y, line);
y += yinc;
}
myfree(packed);
myfree(line);
}
else if (compression == BI_RLE4) {
int read_size;
int count;
i_img_dim xlimit = (xsize + 1) / 2 * 2; /* rounded up */
i_tags_add(&im->tags, "bmp_compression_name", 0, "BI_RLE4", -1, 0);
x = 0;
while (1) {
/* there's always at least 2 bytes in a sequence */
if (i_io_read(ig, packed, 2) != 2) {
myfree(packed);
myfree(line);
if (allow_incomplete) {
i_tags_setn(&im->tags, "i_incomplete", 1);
i_tags_setn(&im->tags, "i_lines_read", abs(y - starty));
return im;
}
else {
i_push_error(0, "missing data during decompression");
i_img_destroy(im);
return NULL;
}
}
else if (packed[0]) {
int count = packed[0];
if (x + count > xlimit) {
/* this file is corrupt */
myfree(packed);
myfree(line);
i_push_error(0, "invalid data during decompression");
im_log((aIMCTX, 1, "read 4-bit: scanline overflow x %d + count %d vs xlimit %d (y %d)\n",
(int)x, count, (int)xlimit, (int)y));
i_img_destroy(im);
return NULL;
}