CompositingReasons CompositingReasonFinder::nonStyleDeterminedDirectReasons(const PaintLayer* layer) const
{
CompositingReasons directReasons = CompositingReasonNone;
LayoutObject* layoutObject = layer->layoutObject();
if (hasOverflowScrollTrigger()) {
if (layer->clipParent())
directReasons |= CompositingReasonOutOfFlowClipping;
if (layer->needsCompositedScrolling())
directReasons |= CompositingReasonOverflowScrollingTouch;
}
// Composite |layer| if it is inside of an ancestor scrolling layer, but that
// scrolling layer is not not on the stacking context ancestor chain of |layer|.
// See the definition of the scrollParent property in Layer for more detail.
if (const PaintLayer* scrollingAncestor = layer->ancestorScrollingLayer()) {
if (scrollingAncestor->needsCompositedScrolling() && layer->scrollParent())
directReasons |= CompositingReasonOverflowScrollingParent;
}
if (requiresCompositingForPositionFixed(layer))
directReasons |= CompositingReasonPositionFixed;
directReasons |= layoutObject->additionalCompositingReasons();
ASSERT(!(directReasons & CompositingReasonComboAllStyleDeterminedReasons));
return directReasons;
}
CompositingReasons CompositingReasonFinder::nonStyleDeterminedDirectReasons(const RenderLayer* layer, bool* needToRecomputeCompositingRequirements) const
{
CompositingReasons directReasons = CompositingReasonNone;
RenderObject* renderer = layer->renderer();
if (hasOverflowScrollTrigger()) {
if (requiresCompositingForOutOfFlowClipping(layer))
directReasons |= CompositingReasonOutOfFlowClipping;
if (requiresCompositingForOverflowScrollingParent(layer))
directReasons |= CompositingReasonOverflowScrollingParent;
}
if (requiresCompositingForOverflowScrolling(layer))
directReasons |= CompositingReasonOverflowScrollingTouch;
if (requiresCompositingForPositionSticky(renderer, layer))
directReasons |= CompositingReasonPositionSticky;
if (requiresCompositingForPositionFixed(renderer, layer, 0, needToRecomputeCompositingRequirements))
directReasons |= CompositingReasonPositionFixed;
directReasons |= renderer->additionalCompositingReasons(m_compositingTriggers);
ASSERT(!(directReasons & CompositingReasonComboAllStyleDeterminedReasons));
return directReasons;
}
bool CompositingReasonFinder::requiresCompositingForOverflowScrollingParent(const RenderLayer* layer) const
{
if (!hasOverflowScrollTrigger())
return false;
return layer->scrollParent();
}
