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Fixed blitting bitmaps with a non-zero x offset

Browse Source 
Also added basic testautomation coverage of bitmap blits

Fixes https://github.com/libsdl-org/sdl2-compat/issues/546
This commit is contained in:
Sam Lantinga
2025-11-06 22:13:22 -08:00
parent a71b2f0a93
commit a2ed1a4197
4 changed files with 290 additions and 40 deletions
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21
src/video/SDL_blit.c
View File

@@ -64,17 +64,26 @@ static bool SDLCALL SDL_SoftBlit(SDL_Surface *src, const SDL_Rect *srcrect,
SDL_BlitInfo *info = &src->map.info;
// Set up the blit information
info->src = (Uint8 *)src->pixels +
(Uint16)srcrect->y * src->pitch +
(Uint16)srcrect->x * info->src_fmt->bytes_per_pixel;
if (info->src_fmt->bits_per_pixel >= 8) {
info->src = (Uint8 *)src->pixels +
srcrect->y * src->pitch +
srcrect->x * info->src_fmt->bytes_per_pixel;
} else {
info->src = (Uint8 *)src->pixels +
srcrect->y * src->pitch +
(srcrect->x * info->src_fmt->bits_per_pixel) / 8;
info->leading_skip =
((srcrect->x * info->src_fmt->bits_per_pixel) % 8) /
info->src_fmt->bits_per_pixel;
}
info->src_w = srcrect->w;
info->src_h = srcrect->h;
info->src_pitch = src->pitch;
info->src_skip =
info->src_pitch - info->src_w * info->src_fmt->bytes_per_pixel;
info->dst =
(Uint8 *)dst->pixels + (Uint16)dstrect->y * dst->pitch +
(Uint16)dstrect->x * info->dst_fmt->bytes_per_pixel;
info->dst = (Uint8 *)dst->pixels +
dstrect->y * dst->pitch +
dstrect->x * info->dst_fmt->bytes_per_pixel;
info->dst_w = dstrect->w;
info->dst_h = dstrect->h;
info->dst_pitch = dst->pitch;

1
src/video/SDL_blit.h
View File

@@ -60,6 +60,7 @@ typedef struct
int src_w, src_h;
int src_pitch;
int src_skip;
int leading_skip;
SDL_Surface *dst_surface;
Uint8 *dst;
int dst_w, dst_h;

218
src/video/SDL_blit_0.c
View File

@@ -45,6 +45,8 @@ SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
dstskip = info->dst_skip;
map = info->table;
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -56,7 +58,13 @@ SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -73,7 +81,13 @@ SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -92,7 +106,13 @@ SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -109,7 +129,13 @@ SDL_FORCE_INLINE void BlitBto1(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -147,6 +173,8 @@ SDL_FORCE_INLINE void BlitBto2(SDL_BlitInfo *info, const Uint32 srcbpp)
dstskip = info->dst_skip / 2;
map = (Uint16 *)info->table;
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -157,7 +185,13 @@ SDL_FORCE_INLINE void BlitBto2(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -174,7 +208,13 @@ SDL_FORCE_INLINE void BlitBto2(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -210,6 +250,8 @@ SDL_FORCE_INLINE void BlitBto3(SDL_BlitInfo *info, const Uint32 srcbpp)
dstskip = info->dst_skip;
map = info->table;
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -220,7 +262,13 @@ SDL_FORCE_INLINE void BlitBto3(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -240,7 +288,13 @@ SDL_FORCE_INLINE void BlitBto3(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -280,6 +334,8 @@ SDL_FORCE_INLINE void BlitBto4(SDL_BlitInfo *info, const Uint32 srcbpp)
dstskip = info->dst_skip / 4;
map = (Uint32 *)info->table;
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -290,7 +346,13 @@ SDL_FORCE_INLINE void BlitBto4(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -307,7 +369,13 @@ SDL_FORCE_INLINE void BlitBto4(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -339,7 +407,8 @@ SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
Uint8 *palmap = info->table;
int c;
// Set up some basic variables
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -351,7 +420,13 @@ SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -368,7 +443,13 @@ SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -387,7 +468,13 @@ SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -404,7 +491,13 @@ SDL_FORCE_INLINE void BlitBto1Key(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -437,7 +530,8 @@ SDL_FORCE_INLINE void BlitBto2Key(SDL_BlitInfo *info, const Uint32 srcbpp)
Uint8 *palmap = info->table;
int c;
// Set up some basic variables
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -449,7 +543,13 @@ SDL_FORCE_INLINE void BlitBto2Key(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -466,7 +566,13 @@ SDL_FORCE_INLINE void BlitBto2Key(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -498,7 +604,8 @@ SDL_FORCE_INLINE void BlitBto3Key(SDL_BlitInfo *info, const Uint32 srcbpp)
Uint8 *palmap = info->table;
int c;
// Set up some basic variables
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -509,7 +616,13 @@ SDL_FORCE_INLINE void BlitBto3Key(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -526,7 +639,13 @@ SDL_FORCE_INLINE void BlitBto3Key(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -558,7 +677,8 @@ SDL_FORCE_INLINE void BlitBto4Key(SDL_BlitInfo *info, const Uint32 srcbpp)
Uint8 *palmap = info->table;
int c;
// Set up some basic variables
width += info->leading_skip;
if (srcbpp == 4)
srcskip += width - (width + 1) / 2;
else if (srcbpp == 2)
@@ -570,7 +690,13 @@ SDL_FORCE_INLINE void BlitBto4Key(SDL_BlitInfo *info, const Uint32 srcbpp)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -587,7 +713,13 @@ SDL_FORCE_INLINE void BlitBto4Key(SDL_BlitInfo *info, const Uint32 srcbpp)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -622,7 +754,8 @@ static void BlitBtoNAlpha(SDL_BlitInfo *info)
unsigned dR, dG, dB, dA;
const unsigned A = info->a;
// Set up some basic variables
width += info->leading_skip;
srcbpp = srcfmt->bytes_per_pixel;
dstbpp = dstfmt->bytes_per_pixel;
if (srcbpp == 4)
@@ -637,7 +770,13 @@ static void BlitBtoNAlpha(SDL_BlitInfo *info)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -659,7 +798,13 @@ static void BlitBtoNAlpha(SDL_BlitInfo *info)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -700,7 +845,8 @@ static void BlitBtoNAlphaKey(SDL_BlitInfo *info)
const unsigned A = info->a;
Uint32 ckey = info->colorkey;
// Set up some basic variables
width += info->leading_skip;
srcbpp = srcfmt->bytes_per_pixel;
dstbpp = dstfmt->bytes_per_pixel;
if (srcbpp == 4)
@@ -715,7 +861,13 @@ static void BlitBtoNAlphaKey(SDL_BlitInfo *info)
if (SDL_PIXELORDER(info->src_fmt->format) == SDL_BITMAPORDER_4321) {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte >>= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}
@@ -737,7 +889,13 @@ static void BlitBtoNAlphaKey(SDL_BlitInfo *info)
} else {
while (height--) {
Uint8 byte = 0, bit;
for (c = 0; c < width; ++c) {
for (c = 0; c < info->leading_skip; ++c) {
if (!(c & align)) {
byte = *src++;
}
byte <<= srcbpp;
}
for (; c < width; ++c) {
if (!(c & align)) {
byte = *src++;
}