[SPV2] Implement the blink-side scroll property tree

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index f57b66166d4eb51fe2e352176ad8449a072603d3..b7a9dc05e9105209a0895cd6a091918953d3d78c 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -28,12 +28,14 @@ void PaintPropertyTreeBuilder::buildTreeRootNodes(FrameView& rootFrame, PaintPro
         rootFrame.setRootTransform(TransformPaintPropertyNode::create(nullptr, TransformationMatrix(), FloatPoint3D()));
         rootFrame.setRootClip(ClipPaintPropertyNode::create(nullptr, rootFrame.rootTransform(), FloatRoundedRect(LayoutRect::infiniteIntRect())));
         rootFrame.setRootEffect(EffectPaintPropertyNode::create(nullptr, 1.0));
+        rootFrame.setRootScroll(ScrollPaintPropertyNode::create(nullptr, rootFrame.rootTransform(), IntSize(), IntSize(), false, false));
     } else {
         DCHECK(rootFrame.rootClip() && !rootFrame.rootClip()->parent());
         DCHECK(rootFrame.rootEffect() && !rootFrame.rootEffect()->parent());
     }
 
     context.current.transform = context.absolutePosition.transform = context.fixedPosition.transform = rootFrame.rootTransform();
+    context.current.scroll = rootFrame.rootScroll();
     context.current.clip = context.absolutePosition.clip = context.fixedPosition.clip = rootFrame.rootClip();
     context.currentEffect = rootFrame.rootEffect();
 }
@@ -51,6 +53,8 @@ void PaintPropertyTreeBuilder::buildTreeNodes(FrameView& frameView, PaintPropert
             frameView.y() + layoutView->location().y() + context.current.paintOffset.y());
         context.current.transform = layoutView->getMutableForPainting().ensureObjectPaintProperties().createOrUpdatePaintOffsetTranslation(
             context.current.transform, frameTranslate, FloatPoint3D());
+        context.current.scroll = layoutView->getMutableForPainting().ensureObjectPaintProperties().createOrUpdateScroll(
+            context.current.scroll, context.current.transform, IntSize(), IntSize(), false, false);
         context.current.paintOffset = LayoutPoint();
         context.current.renderingContextID = 0;
         context.current.shouldFlattenInheritedTransform = true;
@@ -81,12 +85,22 @@ void PaintPropertyTreeBuilder::buildTreeNodes(FrameView& frameView, PaintPropert
     else
         frameView.setScrollTranslation(TransformPaintPropertyNode::create(frameView.preTranslation(), frameScroll, FloatPoint3D()));
 
+    IntSize scrollClip = frameView.visibleContentSize();
+    IntSize scrollBounds = frameView.contentsSize();
+    bool userScrollableHorizontal = frameView.userInputScrollable(HorizontalScrollbar);
+    bool userScrollableVertical = frameView.userInputScrollable(VerticalScrollbar);
+    if (ScrollPaintPropertyNode* existingScroll = frameView.scroll())

[chrishtr, 2016/09/08 20:43:59]

Maybe add frameview.createOrUpdateScroll() to avoid this conditional?

[pdr., 2016/09/08 23:16:26]

I'd like to avoid putting property tree logic on Layout classes, sort of like
how put paint logic in separate painter classes. For LayoutObject we use
ObjectPaintProperties, but we've been managing FrameView's sloppily in this
function.

How does breaking these createOrUpdates out into helpers in
PaintPropertyTreeBuilder sound to you? In the latest patch I moved the logic
into 4 new functions:
createOrUpdateFrameViewPreTranslation
createOrUpdateFrameViewContentClip
createOrUpdateFrameViewScrollTranslation
createOrUpdateFrameViewScroll

(BTW, all of this will go away with RootLayerScrolls)

[chrishtr, 2016/09/09 16:27:28]

What I mean is to have a method like ensureScroll() so that you don't have to
check whether the scroll was set or not.

+        existingScroll->update(context.current.scroll, frameView.scrollTranslation(), scrollClip, scrollBounds, userScrollableHorizontal, userScrollableVertical);
+    else
+        frameView.setScroll(ScrollPaintPropertyNode::create(context.current.scroll, frameView.scrollTranslation(), scrollClip, scrollBounds, userScrollableHorizontal, userScrollableVertical));
+
     // Initialize the context for current, absolute and fixed position cases.
     // They are the same, except that scroll translation does not apply to
     // fixed position descendants.
     context.current.transform = frameView.scrollTranslation();
     context.current.paintOffset = LayoutPoint();
     context.current.clip = frameView.contentClip();
+    context.current.scroll = frameView.scroll();
     context.current.renderingContextID = 0;
     context.current.shouldFlattenInheritedTransform = true;
     context.absolutePosition = context.current;
@@ -237,6 +251,7 @@ void PaintPropertyTreeBuilder::updateLocalBorderBoxContext(const LayoutObject& o
         wrapUnique(new ObjectPaintProperties::LocalBorderBoxProperties);
     borderBoxContext->paintOffset = context.current.paintOffset;
     borderBoxContext->propertyTreeState = PropertyTreeState(context.current.transform, context.current.clip, context.currentEffect);
+    borderBoxContext->scroll = context.current.scroll;
 
     if (!context.current.clip) {
         DCHECK(object.isLayoutView());
@@ -354,7 +369,7 @@ void PaintPropertyTreeBuilder::updateSvgLocalToBorderBoxTransform(const LayoutOb
     context.current.renderingContextID = 0;
 }
 
-void PaintPropertyTreeBuilder::updateScrollTranslation(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
+void PaintPropertyTreeBuilder::updateScrollAndScrollTranslation(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     if (object.isBoxModelObject() && object.hasOverflowClip()) {
         PaintLayer* layer = toLayoutBoxModelObject(object).layer();
@@ -365,13 +380,23 @@ void PaintPropertyTreeBuilder::updateScrollTranslation(const LayoutObject& objec
             TransformationMatrix matrix = TransformationMatrix().translate(-scrollOffset.width(), -scrollOffset.height());
             context.current.transform = object.getMutableForPainting().ensureObjectPaintProperties().createOrUpdateScrollTranslation(
                 context.current.transform, matrix, FloatPoint3D(), context.current.shouldFlattenInheritedTransform, context.current.renderingContextID);
+
+            IntSize scrollClip = layer->getScrollableArea()->visibleContentRect().size();
+            IntSize scrollBounds = layer->getScrollableArea()->contentsSize();
+            bool userScrollableHorizontal = layer->getScrollableArea()->userInputScrollable(HorizontalScrollbar);
+            bool userScrollableVertical = layer->getScrollableArea()->userInputScrollable(VerticalScrollbar);
+            context.current.scroll = object.getMutableForPainting().ensureObjectPaintProperties().createOrUpdateScroll(
+                context.current.scroll, context.current.transform, scrollClip, scrollBounds, userScrollableHorizontal, userScrollableVertical);
+
             context.current.shouldFlattenInheritedTransform = false;
             return;
         }
     }
 
-    if (ObjectPaintProperties* properties = object.getMutableForPainting().objectPaintProperties())
+    if (ObjectPaintProperties* properties = object.getMutableForPainting().objectPaintProperties()) {
         properties->clearScrollTranslation();
+        properties->clearScroll();
+    }
 }
 
 void PaintPropertyTreeBuilder::updateOutOfFlowContext(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
@@ -485,7 +510,7 @@ void PaintPropertyTreeBuilder::buildTreeNodesForChildren(const LayoutObject& obj
     updateOverflowClip(object, context);
     updatePerspective(object, context);
     updateSvgLocalToBorderBoxTransform(object, context);
-    updateScrollTranslation(object, context);
+    updateScrollAndScrollTranslation(object, context);
     updateOutOfFlowContext(object, context);
 }