Changeset 244209 in webkit

Timestamp:

Apr 11, 2019 10:28:50 PM (5 years ago)

Author:

Simon Fraser

Message:

Avoid doing positioned scrolling tree node work for layers not inside overflow:scroll
​https://bugs.webkit.org/show_bug.cgi?id=196848

Reviewed by Zalan Bujtas.

Maintain a bit on RenderLayer which says if a layer has a composited scrolling ancestor
in the layer tree. We only need to do work related to making positioned scrolling tree nodes
for layers which are layer tree descendants of overflow:scroll.

• rendering/RenderLayer.cpp:

(WebCore::RenderLayer::RenderLayer):
(WebCore::RenderLayer::updateLayerPositions):
(WebCore::outputPaintOrderTreeLegend):
(WebCore::outputPaintOrderTreeRecursive):

• rendering/RenderLayer.h:
• rendering/RenderLayerCompositor.cpp:

(WebCore::RenderLayerCompositor::requiresCompositingForPosition const):
(WebCore::RenderLayerCompositor::requiresCompositingForIndirectReason const):
(WebCore::RenderLayerCompositor::isViewportConstrainedFixedOrStickyLayer const):
(WebCore::RenderLayerCompositor::fixedLayerIntersectsViewport const):
(WebCore::RenderLayerCompositor::computeCoordinatedPositioningForLayer const):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• rendering/RenderLayer.cpp (modified) (6 diffs)
• rendering/RenderLayer.h (modified) (3 diffs)
• rendering/RenderLayerCompositor.cpp (modified) (5 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-04-11  Simon Fraser  <simon.fraser@apple.com>
+
+        Avoid doing positioned scrolling tree node work for layers not inside overflow:scroll
+        https://bugs.webkit.org/show_bug.cgi?id=196848
+
+        Reviewed by Zalan Bujtas.
+
+        Maintain a bit on RenderLayer which says if a layer has a composited scrolling ancestor
+        in the layer tree. We only need to do work related to making positioned scrolling tree nodes
+        for layers which are layer tree descendants of overflow:scroll.
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::RenderLayer):
+        (WebCore::RenderLayer::updateLayerPositions):
+        (WebCore::outputPaintOrderTreeLegend):
+        (WebCore::outputPaintOrderTreeRecursive):
+        * rendering/RenderLayer.h:
+        * rendering/RenderLayerCompositor.cpp:
+        (WebCore::RenderLayerCompositor::requiresCompositingForPosition const):
+        (WebCore::RenderLayerCompositor::requiresCompositingForIndirectReason const):
+        (WebCore::RenderLayerCompositor::isViewportConstrainedFixedOrStickyLayer const):
+        (WebCore::RenderLayerCompositor::fixedLayerIntersectsViewport const):
+        (WebCore::RenderLayerCompositor::computeCoordinatedPositioningForLayer const):
+
 2019-04-11  Zalan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayer.cpp

@@ -292 +292 @@
     , m_has3DTransformedDescendant(false)
     , m_hasCompositingDescendant(false)
+    , m_hasCompositedScrollingAncestor(false)
     , m_hasTransformedAncestor(false)
     , m_has3DTransformedAncestor(false)
@@ -912 +913 @@
     m_hasTransformedAncestor = flags.contains(SeenTransformedLayer);
     m_has3DTransformedAncestor = flags.contains(Seen3DTransformedLayer);
+    setHasCompositedScrollingAncestor(flags.contains(SeenCompositedScrollingLayer));
 
     // Update the reflection's position and size.
@@ -927 +929 @@
             flags.add(Seen3DTransformedLayer);
     }
+    
+    if (hasCompositedScrollableOverflow())
+        flags.add(SeenCompositedScrollingLayer);
 
     for (RenderLayer* child = firstChild(); child; child = child->nextSibling())
@@ -940 +945 @@
     }
 
-    if (renderer().isOutOfFlowPositioned() && renderer().style().position() == PositionType::Fixed && renderer().settings().acceleratedCompositingForFixedPositionEnabled()) {
+    if (renderer().isFixedPositioned() && renderer().settings().acceleratedCompositingForFixedPositionEnabled()) {
         bool intersectsViewport = compositor().fixedLayerIntersectsViewport(*this);
         if (intersectsViewport != m_isFixedIntersectingViewport) {
@@ -6751 +6756 @@
 {
     stream.nextLine();
-    stream << "(S)tacking Context, (N)ormal flow only, (O)verflow clip, (A)lpha (opacity or mask), has (B)lend mode, (I)solates blending, (T)ransform-ish, (F)ilter, Fi(X)ed position, (C)omposited, (c)omposited descendant\n"
+    stream << "(S)tacking Context, (N)ormal flow only, (O)verflow clip, (A)lpha (opacity or mask), has (B)lend mode, (I)solates blending, (T)ransform-ish, (F)ilter, Fi(X)ed position, (C)omposited, (c)omposited descendant, (s)scrolling ancestor\n"
         "Dirty (z)-lists, Dirty (n)ormal flow lists\n"
         "Traversal needs: requirements (t)raversal on descendants, (b)acking or hierarchy traversal on descendants, (r)equirements traversal on all descendants, requirements traversal on all (s)ubsequent layers, (h)ierarchy traversal on all descendants, update of paint (o)rder children\n"
@@ -6778 +6783 @@
     stream << (layer.isComposited() ? "C" : "-");
     stream << (layer.hasCompositingDescendant() ? "c" : "-");
+    stream << (layer.hasCompositedScrollingAncestor() ? "s" : "-");
 
     stream << " ";

trunk/Source/WebCore/rendering/RenderLayer.h

@@ -517 +517 @@
         SeenTransformedLayer                = 1 << 4,
         Seen3DTransformedLayer              = 1 << 5,
+        SeenCompositedScrollingLayer        = 1 << 6,
     };
     static constexpr OptionSet<UpdateLayerPositionsFlag> updateLayerPositionsDefaultFlags() { return { CheckForRepaint }; }
@@ -815 +816 @@
     bool usesAsyncScrolling() const override;
 
+    bool hasCompositedScrollingAncestor() const { return m_hasCompositedScrollingAncestor; }
+    void setHasCompositedScrollingAncestor(bool hasCompositedScrollingAncestor) { m_hasCompositedScrollingAncestor = hasCompositedScrollingAncestor; }
+
     bool paintsWithTransparency(OptionSet<PaintBehavior> paintBehavior) const
     {
@@ -1202 +1206 @@
     bool m_hasCompositingDescendant : 1; // In the z-order tree.
 
+    bool m_hasCompositedScrollingAncestor : 1; // In the layer-order tree.
+
     bool m_hasTransformedAncestor : 1;
     bool m_has3DTransformedAncestor : 1;

trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp

@@ -2716 +2716 @@
 
     auto position = renderer.style().position();
-    bool isFixed = renderer.isOutOfFlowPositioned() && position == PositionType::Fixed;
+    bool isFixed = renderer.isFixedPositioned();
     if (isFixed && !layer.isStackingContext())
         return false;
@@ -2801 +2801 @@
     }
 
-    if (renderer.isAbsolutelyPositioned() && compositingAncestor) {
+    if (renderer.isAbsolutelyPositioned() && compositingAncestor && layer.hasCompositedScrollingAncestor()) {
         if (layerContainingBlockCrossesCoordinatedScrollingBoundary(layer, *compositingAncestor)) {
             reason = RenderLayer::IndirectCompositingReason::OverflowScrollPositioning;
@@ -2863 +2863 @@
         return isAsyncScrollableStickyLayer(layer);
 
-    if (layer.renderer().style().position() != PositionType::Fixed)
+    if (!layer.renderer().isFixedPositioned())
         return false;
 
@@ -2877 +2877 @@
 bool RenderLayerCompositor::fixedLayerIntersectsViewport(const RenderLayer& layer) const
 {
-    ASSERT(layer.renderer().style().position() == PositionType::Fixed);
+    ASSERT(layer.renderer().isFixedPositioned());
 
     // Fixed position elements that are invisible in the current view don't get their own layer.
@@ -2947 +2947 @@
 
     if (layer.renderer().isFixedPositioned())
+        return ScrollPositioningBehavior::None;
+    
+    if (!layer.hasCompositedScrollingAncestor())
         return ScrollPositioningBehavior::None;