A zero source rect is valid for blitting

A zero sized source rect draws pixels sourced from a 0x0 region on the source surface.

Fixes https://github.com/libsdl-org/SDL/issues/8580
This commit is contained in:
Sam Lantinga 2024-09-25 22:15:20 -07:00
parent 1aea43846e
commit 345d9bfe19
3 changed files with 28 additions and 2 deletions

View File

@ -59,7 +59,7 @@ static bool SDLCALL SDL_SoftBlit(SDL_Surface *src, const SDL_Rect *srcrect,
}
// Set up source and destination buffer pointers, and BLIT!
if (okay && !SDL_RectEmpty(srcrect)) {
if (okay) {
SDL_BlitFunc RunBlit;
SDL_BlitInfo *info = &src->internal->map.info;

View File

@ -1226,7 +1226,7 @@ bool SDL_BlitSurfaceScaled(SDL_Surface *src, const SDL_Rect *srcrect, SDL_Surfac
SDL_GetRectIntersection(clip_rect, &final_dst, &final_dst);
if (final_dst.w == 0 || final_dst.h == 0 ||
final_src.w <= 0 || final_src.h <= 0) {
final_src.w < 0 || final_src.h < 0) {
// No-op.
return true;
}

View File

@ -821,6 +821,27 @@ static int SDLCALL surface_testLoadFailure(void *arg)
return TEST_COMPLETED;
}
/**
* Tests blitting from a zero sized source rectangle
*/
static int SDLCALL surface_testBlitZeroSource(void *arg)
{
SDL_Surface *src = SDL_CreateSurface(1, 1, SDL_PIXELFORMAT_RGBA8888);
SDL_Surface *dst = SDL_CreateSurface(1, 1, SDL_PIXELFORMAT_RGBA8888);
SDL_Rect srcrect = { 0, 0, 0, 0 };
int ret;
SDLTest_AssertPass("Call to SDL_BlitSurfaceScaled() with zero sized source rectangle");
SDL_FillSurfaceRect(src, NULL, SDL_MapSurfaceRGB(src, 255, 255, 255));
SDL_BlitSurfaceScaled(src, &srcrect, dst, NULL, SDL_SCALEMODE_NEAREST);
ret = SDLTest_CompareSurfaces(dst, src, 0);
SDLTest_AssertCheck(ret == 0, "Validate result from SDLTest_CompareSurfaces, expected: 0, got: %i", ret);
SDL_DestroySurface(src);
SDL_DestroySurface(dst);
return TEST_COMPLETED;
}
/**
* Tests some blitting routines.
*/
@ -1465,6 +1486,10 @@ static const SDLTest_TestCaseReference surfaceTestSaveLoadBitmap = {
surface_testSaveLoadBitmap, "surface_testSaveLoadBitmap", "Tests sprite saving and loading.", TEST_ENABLED
};
static const SDLTest_TestCaseReference surfaceTestBlitZeroSource = {
surface_testBlitZeroSource, "surface_testBlitZeroSource", "Tests blitting from a zero sized source rectangle", TEST_ENABLED
};
static const SDLTest_TestCaseReference surfaceTestBlit = {
surface_testBlit, "surface_testBlit", "Tests basic blitting.", TEST_ENABLED
};
@ -1552,6 +1577,7 @@ static const SDLTest_TestCaseReference surfaceTestPremultiplyAlpha = {
/* Sequence of Surface test cases */
static const SDLTest_TestCaseReference *surfaceTests[] = {
&surfaceTestSaveLoadBitmap,
&surfaceTestBlitZeroSource,
&surfaceTestBlit,
&surfaceTestBlitTiled,
&surfaceTestBlit9Grid,