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Fixed bug #7614: Segmentation Fault in SDL_BlitSurface (#7808) 

Update SDL_BlitSurface to use Intersect functions

(cherry picked from commit 3639743d89)
This commit is contained in:
Sylvain Becker 2024-01-19 17:39:57 +01:00 committed by Sam Lantinga
parent 87b5bb5840
commit bb969ac747
1 changed files with 51 additions and 70 deletions
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121
src/video/SDL_surface.c
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@ -701,86 +701,65 @@ int SDL_LowerBlit(SDL_Surface *src, SDL_Rect *srcrect,
int SDL_UpperBlit(SDL_Surface *src, const SDL_Rect *srcrect,
SDL_Surface *dst, SDL_Rect *dstrect)
{
SDL_Rect fulldst;
int srcx, srcy;
Sint64 w, h;
SDL_Rect r_src, r_dst;
/* Make sure the surfaces aren't locked */
if (!src || !dst) {
return SDL_InvalidParamError("SDL_UpperBlit(): src/dst");
}
if (src->locked || dst->locked) {
if (!src) {
return SDL_InvalidParamError("src");
} else if (!dst) {
return SDL_InvalidParamError("dst");
} else if (src->locked || dst->locked) {
return SDL_SetError("Surfaces must not be locked during blit");
}
/* If the destination rectangle is NULL, use the entire dest surface */
if (!dstrect) {
fulldst.x = fulldst.y = 0;
fulldst.w = dst->w;
fulldst.h = dst->h;
dstrect = &fulldst;
/* Full src surface */
r_src.x = 0;
r_src.y = 0;
r_src.w = src->w;
r_src.h = src->h;
if (dstrect) {
r_dst.x = dstrect->x;
r_dst.y = dstrect->y;
} else {
r_dst.x = 0;
r_dst.y = 0;
}
/* clip the source rectangle to the source surface */
if (srcrect) {
int maxw, maxh;
srcx = srcrect->x;
w = srcrect->w;
if (srcx < 0) {
w += srcx;
dstrect->x -= srcx;
srcx = 0;
}
maxw = src->w - srcx;
if (maxw < w) {
w = maxw;
SDL_Rect tmp;
if (SDL_IntersectRect(srcrect, &r_src, &tmp) == SDL_FALSE) {
goto end;
}
srcy = srcrect->y;
h = srcrect->h;
if (srcy < 0) {
h += srcy;
dstrect->y -= srcy;
srcy = 0;
}
maxh = src->h - srcy;
if (maxh < h) {
h = maxh;
}
/* Shift dstrect, if srcrect origin has changed */
r_dst.x += tmp.x - srcrect->x;
r_dst.y += tmp.y - srcrect->y;
} else {
srcx = srcy = 0;
w = src->w;
h = src->h;
/* Update srcrect */
r_src = tmp;
}
/* There're no dstrect.w/h parameters. It's the same as srcrect */
r_dst.w = r_src.w;
r_dst.h = r_src.h;
/* clip the destination rectangle against the clip rectangle */
{
SDL_Rect *clip = &dst->clip_rect;
int dx, dy;
dx = clip->x - dstrect->x;
if (dx > 0) {
w -= dx;
dstrect->x += dx;
srcx += dx;
}
dx = dstrect->x + w - clip->x - clip->w;
if (dx > 0) {
w -= dx;
SDL_Rect tmp;
if (SDL_IntersectRect(&r_dst, &dst->clip_rect, &tmp) == SDL_FALSE) {
goto end;
}
dy = clip->y - dstrect->y;
if (dy > 0) {
h -= dy;
dstrect->y += dy;
srcy += dy;
}
dy = dstrect->y + h - clip->y - clip->h;
if (dy > 0) {
h -= dy;
}
/* Shift srcrect, if dstrect has changed */
r_src.x += tmp.x - r_dst.x;
r_src.y += tmp.y - r_dst.y;
r_src.w = tmp.w;
r_src.h = tmp.h;
/* Update dstrect */
r_dst = tmp;
}
/* Switch back to a fast blit if we were previously stretching */
@ -789,15 +768,17 @@ int SDL_UpperBlit(SDL_Surface *src, const SDL_Rect *srcrect,
SDL_InvalidateMap(src->map);
}
if (w > 0 && h > 0) {
SDL_Rect sr;
sr.x = srcx;
sr.y = srcy;
sr.w = dstrect->w = w;
sr.h = dstrect->h = h;
return SDL_LowerBlit(src, &sr, dst, dstrect);
if (r_dst.w > 0 && r_dst.h > 0) {
if (dstrect) { /* update output parameter */
*dstrect = r_dst;
}
return SDL_LowerBlit(src, &r_src, dst, dstrect);
}
end:
if (dstrect) { /* update output parameter */
dstrect->w = dstrect->h = 0;
}
dstrect->w = dstrect->h = 0;
return 0;
}