SDL_ShapeTree*
SDL_CalculateShapeTree(SDL_WindowShapeMode mode,SDL_Surface* shape) {
SDL_Rect dimensions = {0,0,shape->w,shape->h};
SDL_ShapeTree* result = NULL;
if(SDL_MUSTLOCK(shape))
SDL_LockSurface(shape);
result = RecursivelyCalculateShapeTree(mode,shape,dimensions);
if(SDL_MUSTLOCK(shape))
SDL_UnlockSurface(shape);
return result;
}
static SDL_ShapeTree*
RecursivelyCalculateShapeTree(SDL_WindowShapeMode mode,SDL_Surface* mask,SDL_Rect dimensions) {
int x = 0,y = 0;
Uint8* pixel = NULL;
Uint32 pixel_value = 0;
Uint8 r = 0,g = 0,b = 0,a = 0;
SDL_bool pixel_opaque = SDL_FALSE;
int last_opaque = -1;
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;
pixel = (Uint8 *)(mask->pixels) + (y*mask->pitch) + (x*mask->format->BytesPerPixel);
switch(mask->format->BytesPerPixel) {
case(1):
pixel_value = *(Uint8*)pixel;
break;
case(2):
pixel_value = *(Uint16*)pixel;
break;
case(3):
pixel_value = *(Uint32*)pixel & (~mask->format->Amask);
break;
case(4):
pixel_value = *(Uint32*)pixel;
break;
}
SDL_GetRGBA(pixel_value,mask->format,&r,&g,&b,&a);
switch(mode.mode) {
case(ShapeModeDefault):
pixel_opaque = (a >= 1 ? SDL_TRUE : SDL_FALSE);
break;
case(ShapeModeBinarizeAlpha):
pixel_opaque = (a >= mode.parameters.binarizationCutoff ? SDL_TRUE : SDL_FALSE);
break;
case(ShapeModeReverseBinarizeAlpha):
pixel_opaque = (a <= mode.parameters.binarizationCutoff ? SDL_TRUE : SDL_FALSE);
break;
case(ShapeModeColorKey):
key = mode.parameters.colorKey;
pixel_opaque = ((key.r != r || key.g != g || key.b != b) ? SDL_TRUE : SDL_FALSE);
break;
}
if(last_opaque == -1)
last_opaque = pixel_opaque;
if(last_opaque != pixel_opaque) {
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;
result->data.children.upleft = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);
next.x += next.w;
/* Unneeded: next.y = dimensions.y; */
result->data.children.upright = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);
next.x = dimensions.x;
next.y += next.h;
result->data.children.downleft = (struct SDL_ShapeTree *)RecursivelyCalculateShapeTree(mode,mask,next);
next.x += next.w;
/* Unneeded: next.y = dimensions.y + dimensions.h /2; */
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;
return result;
}
