static void
ComputeRectsForInsetBoxShadow(gfxIntSize aBlurRadius,
gfxIntSize aSpreadRadius,
const Rect& aDestRect,
const Rect& aShadowClipRect,
Rect& aOutOuterRect,
Rect& aOutInnerRect,
Margin& aOutPathMargins)
{
gfxIntSize marginSize = aBlurRadius + aSpreadRadius;
// The sizes we're given for aBlurRadius/aSpreadRadius are radius'.
// We actually want to paint the whole blur, so we need the diameter.
// We render both the outer / inner blur portions of a blur,
// Then we clip out the outer portion later.
aOutPathMargins.SizeTo(marginSize.height, marginSize.width, marginSize.height, marginSize.width);
aOutPathMargins += aOutPathMargins;
aOutOuterRect.x = 0;
aOutInnerRect.x = marginSize.width;
aOutOuterRect.y = 0;
aOutInnerRect.y = marginSize.height;
// + 1 for the middle edges so we can sample them
aOutInnerRect.width = aOutPathMargins.LeftRight() + 1;
aOutInnerRect.height = aOutPathMargins.TopBottom() + 1;
// The outer path rect needs to be 1 blur radius past the inner edges
aOutOuterRect.width = aOutInnerRect.XMost() + marginSize.width;
aOutOuterRect.height = aOutInnerRect.YMost() + marginSize.height;
if ((aOutOuterRect.width >= aDestRect.width) ||
(aOutOuterRect.height >= aDestRect.height) ||
(aOutInnerRect.width >= aShadowClipRect.width) ||
(aOutInnerRect.height >= aShadowClipRect.height))
{
aOutOuterRect.width = aDestRect.width;
aOutOuterRect.height = aDestRect.height;
aOutInnerRect.width = aShadowClipRect.width;
aOutInnerRect.height = aShadowClipRect.height;
aOutPathMargins.SizeTo(0, 0, 0, 0);
}
}
/***
* We create our minimal rect with 2 rects.
* The first is the inside whitespace rect, that is "cut out"
* from the box. This is (1). This must be the size
* of the blur radius + corner radius so we can have a big enough
* inside cut.
*
* The second (2) is one blur radius surrounding the inner
* frame of (1). This is the amount of blur space required
* to get a proper blend.
*
* B = one blur size
* W = one blur + corner radii - known as inner margin
* ___________________________________
* | |
* | | | |
* | (2) | (1) | (2) |
* | B | W | B |
* | | | |
* | | | |
* | | |
* |________________________________|
*/
static void GetBlurMargins(const RectCornerRadii* aInnerClipRadii,
const IntSize& aBlurRadius,
Margin& aOutBlurMargin,
Margin& aOutInnerMargin)
{
Size cornerSize(0, 0);
if (aInnerClipRadii) {
const RectCornerRadii& corners = *aInnerClipRadii;
NS_FOR_CSS_FULL_CORNERS(i) {
cornerSize.width = std::max(cornerSize.width, corners[i].width);
cornerSize.height = std::max(cornerSize.height, corners[i].height);
}
}
// Only the inside whitespace size cares about the border radius size.
// Outer sizes only care about blur.
IntSize margin = IntSize::Ceil(cornerSize) + aBlurRadius;
aOutInnerMargin.SizeTo(margin.height, margin.width,
margin.height, margin.width);
aOutBlurMargin.SizeTo(aBlurRadius.height, aBlurRadius.width,
aBlurRadius.height, aBlurRadius.width);
}
