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Fix non-power-of-two shaped windows.

This fixes a bug where SDL_SetWindowShape would render artifacts if the image
was not a power of two image, due to rounding of width / 2.
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jorgenpt committed Sep 2, 2014
1 parent 7242e81 commit 782d590b77aa8273e7f11f6e916bc693d36dea90
Showing with 20 additions and 9 deletions.
  1. +20 −9 src/video/SDL_shape.c
@@ -128,6 +128,7 @@ RecursivelyCalculateShapeTree(SDL_WindowShapeMode mode,SDL_Surface* mask,SDL_Rec
SDL_Color key;
SDL_ShapeTree* result = (SDL_ShapeTree*)SDL_malloc(sizeof(SDL_ShapeTree));
SDL_Rect next = {0,0,0,0};

for(y=dimensions.y;y<dimensions.y + dimensions.h;y++) {
for(x=dimensions.x;x<dimensions.x + dimensions.w;x++) {
pixel_value = 0;
@@ -165,27 +166,37 @@ RecursivelyCalculateShapeTree(SDL_WindowShapeMode mode,SDL_Surface* mask,SDL_Rec
if(last_opaque == -1)
last_opaque = pixel_opaque;
if(last_opaque != pixel_opaque) {
const int halfwidth = dimensions.w / 2;
const int halfheight = dimensions.h / 2;

result->kind = QuadShape;
/* These will stay the same. */
next.w = dimensions.w / 2;
next.h = dimensions.h / 2;
/* These will change from recursion to recursion. */

next.x = dimensions.x;
next.y = dimensions.y;
next.w = halfwidth;
next.h = halfheight;
result->data.children.upleft = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);
next.x += next.w;
/* Unneeded: next.y = dimensions.y; */

next.x = dimensions.x + halfwidth;
next.w = dimensions.w - halfwidth;
result->data.children.upright = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);

next.x = dimensions.x;
next.y += next.h;
next.w = halfwidth;
next.y = dimensions.y + halfheight;
next.h = dimensions.h - halfheight;
result->data.children.downleft = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);
next.x += next.w;
/* Unneeded: next.y = dimensions.y + dimensions.h /2; */

next.x = dimensions.x + halfwidth;
next.w = dimensions.w - halfwidth;
result->data.children.downright = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);

return result;
}
}
}


/* If we never recursed, all the pixels in this quadrant have the same "value". */
result->kind = (last_opaque == SDL_TRUE ? OpaqueShape : TransparentShape);
result->data.shape = dimensions;

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