C++ PaintLayer::hasCompositedLayerMapping方法代码示例

void GraphicsLayerTreeBuilder::rebuild(PaintLayer& layer, AncestorInfo info)
{
    // Make the layer compositing if necessary, and set up clipping and content layers.
    // Note that we can only do work here that is independent of whether the descendant layers
    // have been processed. computeCompositingRequirements() will already have done the paint invalidation if necessary.

    layer.stackingNode()->updateLayerListsIfNeeded();

    const bool hasCompositedLayerMapping = layer.hasCompositedLayerMapping();
    CompositedLayerMapping* currentCompositedLayerMapping = layer.compositedLayerMapping();

    // If this layer has a compositedLayerMapping, then that is where we place subsequent children GraphicsLayers.
    // Otherwise children continue to append to the child list of the enclosing layer.
    GraphicsLayerVector layerChildren;
    AncestorInfo infoForChildren(info);
    if (hasCompositedLayerMapping) {
        infoForChildren.childLayersOfEnclosingCompositedLayer = &layerChildren;
        infoForChildren.enclosingCompositedLayer = &layer;
    }

#if ENABLE(ASSERT)
    LayerListMutationDetector mutationChecker(layer.stackingNode());
#endif

    if (layer.stackingNode()->isStackingContext()) {
        PaintLayerStackingNodeIterator iterator(*layer.stackingNode(), NegativeZOrderChildren);
        while (PaintLayerStackingNode* curNode = iterator.next())
            rebuild(*curNode->layer(), infoForChildren);

        // If a negative z-order child is compositing, we get a foreground layer which needs to get parented.
        if (hasCompositedLayerMapping && currentCompositedLayerMapping->foregroundLayer())
            infoForChildren.childLayersOfEnclosingCompositedLayer->append(currentCompositedLayerMapping->foregroundLayer());
    }

    PaintLayerStackingNodeIterator iterator(*layer.stackingNode(), NormalFlowChildren | PositiveZOrderChildren);
    while (PaintLayerStackingNode* curNode = iterator.next())
        rebuild(*curNode->layer(), infoForChildren);

    if (hasCompositedLayerMapping) {
        bool parented = false;
        if (layer.layoutObject()->isLayoutPart())
            parented = PaintLayerCompositor::attachFrameContentLayersToIframeLayer(toLayoutPart(layer.layoutObject()));

        if (!parented)
            currentCompositedLayerMapping->setSublayers(layerChildren);

        if (shouldAppendLayer(layer))
            info.childLayersOfEnclosingCompositedLayer->append(currentCompositedLayerMapping->childForSuperlayers());
    }

    if (layer.scrollParent()
        && layer.scrollParent()->hasCompositedLayerMapping()
        && layer.scrollParent()->compositedLayerMapping()->needsToReparentOverflowControls()
        && layer.scrollParent()->getScrollableArea()->topmostScrollChild() == &layer)
        info.childLayersOfEnclosingCompositedLayer->append(layer.scrollParent()->compositedLayerMapping()->detachLayerForOverflowControls(*info.enclosingCompositedLayer));
}

static CompositedLayerMapping* mappingFromElement(Element* element) {
  if (!element)
    return nullptr;
  LayoutObject* layoutObject = element->layoutObject();
  if (!layoutObject || !layoutObject->isBoxModelObject())
    return nullptr;
  PaintLayer* layer = toLayoutBoxModelObject(layoutObject)->layer();
  if (!layer)
    return nullptr;
  if (!layer->hasCompositedLayerMapping())
    return nullptr;
  return layer->compositedLayerMapping();
}

bool PaintLayerCompositor::attachFrameContentLayersToIframeLayer(LayoutPart* layoutObject)
{
    PaintLayerCompositor* innerCompositor = frameContentsCompositor(layoutObject);
    if (!innerCompositor || !innerCompositor->staleInCompositingMode() || innerCompositor->rootLayerAttachment() != RootLayerAttachedViaEnclosingFrame)
        return false;

    PaintLayer* layer = layoutObject->layer();
    if (!layer->hasCompositedLayerMapping())
        return false;

    layer->compositedLayerMapping()->setSublayers(GraphicsLayerVector(1, innerCompositor->rootGraphicsLayer()));
    return true;
}

static WebLayer* webLayerFromElement(Element* element)
{
    if (!element)
        return 0;
    LayoutObject* layoutObject = element->layoutObject();
    if (!layoutObject || !layoutObject->isBoxModelObject())
        return 0;
    PaintLayer* layer = toLayoutBoxModelObject(layoutObject)->layer();
    if (!layer)
        return 0;
    if (!layer->hasCompositedLayerMapping())
        return 0;
    CompositedLayerMapping* compositedLayerMapping = layer->compositedLayerMapping();
    GraphicsLayer* graphicsLayer = compositedLayerMapping->mainGraphicsLayer();
    if (!graphicsLayer)
        return 0;
    return graphicsLayer->platformLayer();
}

bool PaintLayerCompositor::allocateOrClearCompositedLayerMapping(PaintLayer* layer, const CompositingStateTransitionType compositedLayerUpdate)
{
    bool compositedLayerMappingChanged = false;

    // FIXME: It would be nice to directly use the layer's compositing reason,
    // but allocateOrClearCompositedLayerMapping also gets called without having updated compositing
    // requirements fully.
    switch (compositedLayerUpdate) {
    case AllocateOwnCompositedLayerMapping:
        ASSERT(!layer->hasCompositedLayerMapping());
        setCompositingModeEnabled(true);

        // If we need to issue paint invalidations, do so before allocating the compositedLayerMapping and clearing out the groupedMapping.
        paintInvalidationOnCompositingChange(layer);

        // If this layer was previously squashed, we need to remove its reference to a groupedMapping right away, so
        // that computing paint invalidation rects will know the layer's correct compositingState.
        // FIXME: do we need to also remove the layer from it's location in the squashing list of its groupedMapping?
        // Need to create a test where a squashed layer pops into compositing. And also to cover all other
        // sorts of compositingState transitions.
        layer->setLostGroupedMapping(false);
        layer->setGroupedMapping(nullptr, PaintLayer::InvalidateLayerAndRemoveFromMapping);

        layer->ensureCompositedLayerMapping();
        compositedLayerMappingChanged = true;

        // At this time, the ScrollingCooridnator only supports the top-level frame.
        if (layer->isRootLayer() && m_layoutView.frame()->isLocalRoot()) {
            if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
                scrollingCoordinator->frameViewRootLayerDidChange(m_layoutView.frameView());
        }
        break;
    case RemoveOwnCompositedLayerMapping:
    // PutInSquashingLayer means you might have to remove the composited layer mapping first.
    case PutInSquashingLayer:
        if (layer->hasCompositedLayerMapping()) {
            // If we're removing the compositedLayerMapping from a reflection, clear the source GraphicsLayer's pointer to
            // its replica GraphicsLayer. In practice this should never happen because reflectee and reflection
            // are both either composited, or not composited.
            if (layer->isReflection()) {
                PaintLayer* sourceLayer = toLayoutBoxModelObject(layer->layoutObject()->parent())->layer();
                if (sourceLayer->hasCompositedLayerMapping()) {
                    ASSERT(sourceLayer->compositedLayerMapping()->mainGraphicsLayer()->replicaLayer() == layer->compositedLayerMapping()->mainGraphicsLayer());
                    sourceLayer->compositedLayerMapping()->mainGraphicsLayer()->setReplicatedByLayer(nullptr);
                }
            }

            layer->clearCompositedLayerMapping();
            compositedLayerMappingChanged = true;
        }

        break;
    case RemoveFromSquashingLayer:
    case NoCompositingStateChange:
        // Do nothing.
        break;
    }

    if (compositedLayerMappingChanged && layer->layoutObject()->isLayoutPart()) {
        PaintLayerCompositor* innerCompositor = frameContentsCompositor(toLayoutPart(layer->layoutObject()));
        if (innerCompositor && innerCompositor->staleInCompositingMode())
            innerCompositor->updateRootLayerAttachment();
    }

    if (compositedLayerMappingChanged)
        layer->clipper().clearClipRectsIncludingDescendants(PaintingClipRects);

    // If a fixed position layer gained/lost a compositedLayerMapping or the reason not compositing it changed,
    // the scrolling coordinator needs to recalculate whether it can do fast scrolling.
    if (compositedLayerMappingChanged) {
        if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
            scrollingCoordinator->frameViewFixedObjectsDidChange(m_layoutView.frameView());
    }

    return compositedLayerMappingChanged;
}