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stb_image: fix reading BMP with explicit masks

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This commit is contained in:
Sean Barrett 2020-02-01 04:19:28 -08:00
parent d693c6103a
commit c440a53d06
1 changed files with 10 additions and 4 deletions
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14
stb_image.h
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@ -5121,6 +5121,7 @@ typedef struct
{
int bpp, offset, hsz;
unsigned int mr,mg,mb,ma, all_a;
int extra_read;
} stbi__bmp_data;
static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
@ -5133,6 +5134,7 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
info->offset = stbi__get32le(s);
info->hsz = hsz = stbi__get32le(s);
info->mr = info->mg = info->mb = info->ma = 0;
info->extra_read = 14;
if (hsz != 12 && hsz != 40 && hsz != 56 && hsz != 108 && hsz != 124) return stbi__errpuc("unknown BMP", "BMP type not supported: unknown");
if (hsz == 12) {
@ -5176,6 +5178,7 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
info->mr = stbi__get32le(s);
info->mg = stbi__get32le(s);
info->mb = stbi__get32le(s);
info->extra_read += 12;
// not documented, but generated by photoshop and handled by mspaint
if (info->mr == info->mg && info->mg == info->mb) {
// ?!?!?
@ -5232,10 +5235,13 @@ static void *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req
if (info.hsz == 12) {
if (info.bpp < 24)
psize = (info.offset - 14 - 24) / 3;
psize = (info.offset - info.extra_read - 24) / 3;
} else {
if (info.bpp < 16)
psize = (info.offset - 14 - info.hsz) >> 2;
psize = (info.offset - info.extra_read - info.hsz) >> 2;
}
if (psize == 0) {
STBI_ASSERT(info.offset == (s->img_buffer - s->buffer_start));
}
if (info.bpp == 24 && ma == 0xff000000)
@ -5263,7 +5269,7 @@ static void *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req
if (info.hsz != 12) stbi__get8(s);
pal[i][3] = 255;
}
stbi__skip(s, info.offset - 14 - info.hsz - psize * (info.hsz == 12 ? 3 : 4));
stbi__skip(s, info.offset - info.extra_read - info.hsz - psize * (info.hsz == 12 ? 3 : 4));
if (info.bpp == 1) width = (s->img_x + 7) >> 3;
else if (info.bpp == 4) width = (s->img_x + 1) >> 1;
else if (info.bpp == 8) width = s->img_x;
@ -5312,7 +5318,7 @@ static void *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req
int rshift=0,gshift=0,bshift=0,ashift=0,rcount=0,gcount=0,bcount=0,acount=0;
int z = 0;
int easy=0;
stbi__skip(s, info.offset - 14 - info.hsz);
stbi__skip(s, info.offset - info.extra_read - info.hsz);
if (info.bpp == 24) width = 3 * s->img_x;
else if (info.bpp == 16) width = 2*s->img_x;
else /* bpp = 32 and pad = 0 */ width=0;