// Determines what portion of rect, if any, is unoccluded (not occluded by region). If
// the resulting unoccluded region is not rectangular, we return a rect containing it.
static inline IntRect rectSubtractRegion(const IntRect& rect, const Region& region)
{
Region rectRegion(rect);
Region intersectRegion(intersect(region, rectRegion));
if (intersectRegion.isEmpty())
return rect;
rectRegion.subtract(intersectRegion);
IntRect boundsRect = rectRegion.bounds();
return boundsRect;
}
// Determines what portion of rect, if any, is visible (not occluded by region). If
// the resulting visible region is not rectangular, we just return the original rect.
static IntRect rectSubtractRegion(const Region& region, const IntRect& rect)
{
Region rectRegion(rect);
Region intersectRegion(intersect(region, rectRegion));
if (intersectRegion.isEmpty())
return rect;
// Test if intersectRegion = rectRegion, if so return empty rect.
rectRegion.subtract(intersectRegion);
IntRect boundsRect = rectRegion.bounds();
if (boundsRect.isEmpty())
return boundsRect;
// Test if rectRegion is still a rectangle. If it is, it will be identical to its bounds.
Region boundsRegion(boundsRect);
boundsRegion.subtract(rectRegion);
if (boundsRegion.isEmpty())
return boundsRect;
return rect;
}
