Commit bcaae0b5778ad8f4e2f1e5f4a500a480662dd6cb
2014-09-08T01:36:22
Deal with various .bmp file format variants in SDL_LoadBMP_RW(). This helps when modern versions of The Gimp (and lots of other things) produces a 32-bit bitmap with an alpha channel, or anything with "BI_BITFIELDS" format, since that data is now embedded in the bitmap info header instead of directly following it and we would accidentally skip over embedded versions of it. Fixes Bugzilla #2714.
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diff --git a/src/video/SDL_bmp.c b/src/video/SDL_bmp.c
index e151d20..fcc48c6 100644
--- a/src/video/SDL_bmp.c
+++ b/src/video/SDL_bmp.c
@@ -85,15 +85,17 @@ SDL_LoadBMP_RW(SDL_RWops * src, int freesrc)
int bmpPitch;
int i, pad;
SDL_Surface *surface;
- Uint32 Rmask;
- Uint32 Gmask;
- Uint32 Bmask;
- Uint32 Amask;
+ Uint32 Rmask = 0;
+ Uint32 Gmask = 0;
+ Uint32 Bmask = 0;
+ Uint32 Amask = 0;
SDL_Palette *palette;
Uint8 *bits;
Uint8 *top, *end;
SDL_bool topDown;
int ExpandBMP;
+ SDL_bool haveRGBMasks = SDL_FALSE;
+ SDL_bool haveAlphaMask = SDL_FALSE;
SDL_bool correctAlpha = SDL_FALSE;
/* The Win32 BMP file header (14 bytes) */
@@ -144,15 +146,14 @@ SDL_LoadBMP_RW(SDL_RWops * src, int freesrc)
/* Read the Win32 BITMAPINFOHEADER */
biSize = SDL_ReadLE32(src);
- if (biSize == 12) {
+ if (biSize == 12) { /* really old BITMAPCOREHEADER */
biWidth = (Uint32) SDL_ReadLE16(src);
biHeight = (Uint32) SDL_ReadLE16(src);
/* biPlanes = */ SDL_ReadLE16(src);
biBitCount = SDL_ReadLE16(src);
biCompression = BI_RGB;
- } else {
- const unsigned int headerSize = 40;
-
+ } else if (biSize >= 40) { /* some version of BITMAPINFOHEADER */
+ Uint32 headerSize;
biWidth = SDL_ReadLE32(src);
biHeight = SDL_ReadLE32(src);
/* biPlanes = */ SDL_ReadLE16(src);
@@ -164,6 +165,54 @@ SDL_LoadBMP_RW(SDL_RWops * src, int freesrc)
biClrUsed = SDL_ReadLE32(src);
/* biClrImportant = */ SDL_ReadLE32(src);
+ /* 64 == BITMAPCOREHEADER2, an incompatible OS/2 2.x extension. Skip this stuff for now. */
+ if (biSize == 64) {
+ /* ignore these extra fields. */
+ if (biCompression == BI_BITFIELDS) {
+ /* this value is actually huffman compression in this variant. */
+ SDL_SetError("Compressed BMP files not supported");
+ was_error = SDL_TRUE;
+ goto done;
+ }
+ } else {
+ /* This is complicated. If compression is BI_BITFIELDS, then
+ we have 3 DWORDS that specify the RGB masks. This is either
+ stored here in an BITMAPV2INFOHEADER (which only differs in
+ that it adds these RGB masks) and biSize >= 52, or we've got
+ these masks stored in the exact same place, but strictly
+ speaking, this is the bmiColors field in BITMAPINFO immediately
+ following the legacy v1 info header, just past biSize. */
+ if (biCompression == BI_BITFIELDS) {
+ haveRGBMasks = SDL_TRUE;
+ Rmask = SDL_ReadLE32(src);
+ Gmask = SDL_ReadLE32(src);
+ Bmask = SDL_ReadLE32(src);
+
+ /* ...v3 adds an alpha mask. */
+ if (biSize >= 56) { /* BITMAPV3INFOHEADER; adds alpha mask */
+ haveAlphaMask = SDL_TRUE;
+ Amask = SDL_ReadLE32(src);
+ }
+ } else {
+ /* the mask fields are ignored for v2+ headers if not BI_BITFIELD. */
+ if (biSize >= 52) { /* BITMAPV2INFOHEADER; adds RGB masks */
+ /*Rmask = */ SDL_ReadLE32(src);
+ /*Gmask = */ SDL_ReadLE32(src);
+ /*Bmask = */ SDL_ReadLE32(src);
+ }
+ if (biSize >= 56) { /* BITMAPV3INFOHEADER; adds alpha mask */
+ /*Amask = */ SDL_ReadLE32(src);
+ }
+ }
+
+ /* Insert other fields here; Wikipedia and MSDN say we're up to
+ v5 of this header, but we ignore those for now (they add gamma,
+ color spaces, etc). Ignoring the weird OS/2 2.x format, we
+ currently parse up to v3 correctly (hopefully!). */
+ }
+
+ /* skip any header bytes we didn't handle... */
+ headerSize = (Uint32) (SDL_RWtell(src) - (fp_offset + 14));
if (biSize > headerSize) {
SDL_RWseek(src, (biSize - headerSize), RW_SEEK_CUR);
}
@@ -194,80 +243,46 @@ SDL_LoadBMP_RW(SDL_RWops * src, int freesrc)
}
/* We don't support any BMP compression right now */
- Rmask = Gmask = Bmask = Amask = 0;
switch (biCompression) {
case BI_RGB:
/* If there are no masks, use the defaults */
- if (bfOffBits == (14 + biSize)) {
- /* Default values for the BMP format */
- switch (biBitCount) {
- case 15:
- case 16:
- Rmask = 0x7C00;
- Gmask = 0x03E0;
- Bmask = 0x001F;
- break;
- case 24:
-#if SDL_BYTEORDER == SDL_BIG_ENDIAN
- Rmask = 0x000000FF;
- Gmask = 0x0000FF00;
- Bmask = 0x00FF0000;
-#else
- Rmask = 0x00FF0000;
- Gmask = 0x0000FF00;
- Bmask = 0x000000FF;
-#endif
- break;
- case 32:
- /* We don't know if this has alpha channel or not */
- correctAlpha = SDL_TRUE;
- Amask = 0xFF000000;
- Rmask = 0x00FF0000;
- Gmask = 0x0000FF00;
- Bmask = 0x000000FF;
- break;
- default:
- break;
- }
- break;
- }
- /* Fall through -- read the RGB masks */
-
- case BI_BITFIELDS:
+ SDL_assert(!haveRGBMasks);
+ SDL_assert(!haveAlphaMask);
+ /* Default values for the BMP format */
switch (biBitCount) {
case 15:
case 16:
- Rmask = SDL_ReadLE32(src);
- Gmask = SDL_ReadLE32(src);
- Bmask = SDL_ReadLE32(src);
+ Rmask = 0x7C00;
+ Gmask = 0x03E0;
+ Bmask = 0x001F;
+ break;
+ case 24:
+#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+ Rmask = 0x000000FF;
+ Gmask = 0x0000FF00;
+ Bmask = 0x00FF0000;
+#else
+ Rmask = 0x00FF0000;
+ Gmask = 0x0000FF00;
+ Bmask = 0x000000FF;
+#endif
break;
case 32:
- Rmask = SDL_ReadLE32(src);
- Gmask = SDL_ReadLE32(src);
- Bmask = SDL_ReadLE32(src);
- Amask = SDL_ReadLE32(src);
-
- /* ImageMagick seems to put out bogus masks here. Pick a default. */
- if ((Rmask == 0xFFFFFF) && (Gmask == 0xFFFFFF) &&
- (Bmask == 0xFFFFFF) && (Amask == 0xFFFFFF) ) {
- Amask = 0xFF000000;
- Rmask = 0x00FF0000;
- Gmask = 0x0000FF00;
- Bmask = 0x000000FF;
- } else if ((Rmask == 0xFFFFFF00) && (Gmask == 0xFFFFFF00) &&
- (Bmask == 0xFFFFFF00) && (Amask == 0xFFFFFF00) ) {
- /* argh, The Gimp seems to put out different bogus masks! */
- Amask = 0x000000FF;
- Rmask = 0xFF000000;
- Gmask = 0x00FF0000;
- Bmask = 0x0000FF00;
- }
-
+ /* We don't know if this has alpha channel or not */
+ correctAlpha = SDL_TRUE;
+ Amask = 0xFF000000;
+ Rmask = 0x00FF0000;
+ Gmask = 0x0000FF00;
+ Bmask = 0x000000FF;
break;
default:
break;
}
break;
+
+ case BI_BITFIELDS:
+ break; /* we handled this in the info header. */
+
default:
SDL_SetError("Compressed BMP files not supported");
was_error = SDL_TRUE;