void
LayerManagerComposite::PostProcessLayers(Layer* aLayer,
nsIntRegion& aOpaqueRegion,
LayerIntRegion& aVisibleRegion,
const Maybe<ParentLayerIntRect>& aClipFromAncestors)
{
if (aLayer->Extend3DContext()) {
// For layers participating 3D rendering context, their visible
// region should be empty (invisible), so we pass through them
// without doing anything.
// Direct children of the establisher may have a clip, becaue the
// item containing it; ex. of nsHTMLScrollFrame, may give it one.
Maybe<ParentLayerIntRect> layerClip =
aLayer->AsHostLayer()->GetShadowClipRect();
Maybe<ParentLayerIntRect> ancestorClipForChildren =
IntersectMaybeRects(layerClip, aClipFromAncestors);
MOZ_ASSERT(!layerClip || !aLayer->Combines3DTransformWithAncestors(),
"Only direct children of the establisher could have a clip");
for (Layer* child = aLayer->GetLastChild();
child;
child = child->GetPrevSibling()) {
PostProcessLayers(child, aOpaqueRegion, aVisibleRegion,
ancestorClipForChildren);
}
return;
}
nsIntRegion localOpaque;
// Treat layers on the path to the root of the 3D rendering context as
// a giant layer if it is a leaf.
Matrix4x4 transform = GetAccTransformIn3DContext(aLayer);
Matrix transform2d;
Maybe<IntPoint> integerTranslation;
// If aLayer has a simple transform (only an integer translation) then we
// can easily convert aOpaqueRegion into pre-transform coordinates and include
// that region.
if (transform.Is2D(&transform2d)) {
if (transform2d.IsIntegerTranslation()) {
integerTranslation = Some(IntPoint::Truncate(transform2d.GetTranslation()));
localOpaque = aOpaqueRegion;
localOpaque.MoveBy(-*integerTranslation);
}
}
// Compute a clip that's the combination of our layer clip with the clip
// from our ancestors.
LayerComposite* composite = static_cast<LayerComposite*>(aLayer->AsHostLayer());
Maybe<ParentLayerIntRect> layerClip = composite->GetShadowClipRect();
MOZ_ASSERT(!layerClip || !aLayer->Combines3DTransformWithAncestors(),
"The layer with a clip should not participate "
"a 3D rendering context");
Maybe<ParentLayerIntRect> outsideClip =
IntersectMaybeRects(layerClip, aClipFromAncestors);
// Convert the combined clip into our pre-transform coordinate space, so
// that it can later be intersected with our visible region.
// If our transform is a perspective, there's no meaningful insideClip rect
// we can compute (it would need to be a cone).
Maybe<LayerIntRect> insideClip;
if (outsideClip && !transform.HasPerspectiveComponent()) {
Matrix4x4 inverse = transform;
if (inverse.Invert()) {
Maybe<LayerRect> insideClipFloat =
UntransformBy(ViewAs<ParentLayerToLayerMatrix4x4>(inverse),
ParentLayerRect(*outsideClip),
LayerRect::MaxIntRect());
if (insideClipFloat) {
insideClipFloat->RoundOut();
LayerIntRect insideClipInt;
if (insideClipFloat->ToIntRect(&insideClipInt)) {
insideClip = Some(insideClipInt);
}
}
}
}
Maybe<ParentLayerIntRect> ancestorClipForChildren;
if (insideClip) {
ancestorClipForChildren =
Some(ViewAs<ParentLayerPixel>(*insideClip, PixelCastJustification::MovingDownToChildren));
}
// Save the value of localOpaque, which currently stores the region obscured
// by siblings (and uncles and such), before our descendants contribute to it.
nsIntRegion obscured = localOpaque;
// Recurse on our descendants, in front-to-back order. In this process:
// - Occlusions are computed for them, and they contribute to localOpaque.
// - They recalculate their visible regions, taking ancestorClipForChildren
// into account, and accumulate them into descendantsVisibleRegion.
LayerIntRegion descendantsVisibleRegion;
bool hasPreserve3DChild = false;
for (Layer* child = aLayer->GetLastChild(); child; child = child->GetPrevSibling()) {
PostProcessLayers(child, localOpaque, descendantsVisibleRegion, ancestorClipForChildren);
if (child->Extend3DContext()) {
hasPreserve3DChild = true;
}
}
// Recalculate our visible region.
LayerIntRegion visible = composite->GetShadowVisibleRegion();
// If we have descendants, throw away the visible region stored on this
// layer, and use the region accumulated by our descendants instead.
if (aLayer->GetFirstChild() && !hasPreserve3DChild) {
visible = descendantsVisibleRegion;
}
// Subtract any areas that we know to be opaque.
if (!obscured.IsEmpty()) {
visible.SubOut(LayerIntRegion::FromUnknownRegion(obscured));
}
// Clip the visible region using the combined clip.
if (insideClip) {
visible.AndWith(*insideClip);
}
composite->SetShadowVisibleRegion(visible);
// Transform the newly calculated visible region into our parent's space,
// apply our clip to it (if any), and accumulate it into |aVisibleRegion|
// for the caller to use.
ParentLayerIntRegion visibleParentSpace = TransformBy(
ViewAs<LayerToParentLayerMatrix4x4>(transform), visible);
if (const Maybe<ParentLayerIntRect>& clipRect = composite->GetShadowClipRect()) {
visibleParentSpace.AndWith(*clipRect);
}
aVisibleRegion.OrWith(ViewAs<LayerPixel>(visibleParentSpace,
PixelCastJustification::MovingDownToChildren));
// If we have a simple transform, then we can add our opaque area into
// aOpaqueRegion.
if (integerTranslation &&
!aLayer->HasMaskLayers() &&
aLayer->IsOpaqueForVisibility()) {
if (aLayer->IsOpaque()) {
localOpaque.OrWith(composite->GetFullyRenderedRegion());
}
localOpaque.MoveBy(*integerTranslation);
if (layerClip) {
localOpaque.AndWith(layerClip->ToUnknownRect());
}
aOpaqueRegion.OrWith(localOpaque);
}
}
