First step of PaintInvalidator implementation

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PrePaintTreeWalk.h"
 
 #include "core/dom/DocumentLifecycle.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutView.h"
 
 namespace blink {
 
 struct PrePaintTreeWalkContext {
-    PrePaintTreeWalkContext() { }
-    PrePaintTreeWalkContext(const PaintPropertyTreeBuilderContext& parentTreeBuilderContext)
-        : treeBuilderContext(parentTreeBuilderContext) { }
+    PrePaintTreeWalkContext() : paintInvalidatorContext(treeBuilderContext) { }
+    PrePaintTreeWalkContext(const PrePaintTreeWalkContext& parentContext)
+        : treeBuilderContext(parentContext.treeBuilderContext)
+        , paintInvalidatorContext(treeBuilderContext, parentContext.paintInvalidatorContext)
+    { }
 
     PaintPropertyTreeBuilderContext treeBuilderContext;
-    // This will be initialized by PaintInvalidator::invalidatePaintIfNeeded().
-    // TODO(wangxianzhu): Change to copy-and-update pattern like PaintPropertyTreeBuilderContext.
-    Optional<PaintInvalidatorContext> paintInvalidatorContext;
+    PaintInvalidatorContext paintInvalidatorContext;
 };
 
 void PrePaintTreeWalk::walk(FrameView& rootFrame)
 {
     DCHECK(rootFrame.frame().document()->lifecycle().state() == DocumentLifecycle::InPrePaint);
 
     PrePaintTreeWalkContext rootContext;
     m_propertyTreeBuilder.buildTreeRootNodes(rootFrame, rootContext.treeBuilderContext);
     walk(rootFrame, rootContext);
     m_paintInvalidator.processPendingDelayedPaintInvalidations();
 }
 
 void PrePaintTreeWalk::walk(FrameView& frameView, const PrePaintTreeWalkContext& context)
 {
-    PrePaintTreeWalkContext localContext(context.treeBuilderContext);
+    PrePaintTreeWalkContext localContext(context);
     m_propertyTreeBuilder.buildTreeNodes(frameView, localContext.treeBuilderContext);
 
     if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled())
-        m_paintInvalidator.invalidatePaintIfNeeded(frameView, localContext.treeBuilderContext, localContext.paintInvalidatorContext);
+        m_paintInvalidator.invalidatePaintIfNeeded(frameView, localContext.paintInvalidatorContext);
 
     if (LayoutView* layoutView = frameView.layoutView())
         walk(*layoutView, localContext);
 }
 
 void PrePaintTreeWalk::walk(const LayoutObject& object, const PrePaintTreeWalkContext& context)
 {
-    PrePaintTreeWalkContext localContext(context.treeBuilderContext);
+    PrePaintTreeWalkContext localContext(context);
     m_propertyTreeBuilder.buildTreeNodes(object, localContext.treeBuilderContext);
 
-    if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled() && context.paintInvalidatorContext)
-        m_paintInvalidator.invalidatePaintIfNeeded(object, localContext.treeBuilderContext, *context.paintInvalidatorContext, localContext.paintInvalidatorContext);
+    if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled())
+        m_paintInvalidator.invalidatePaintIfNeeded(object, localContext.paintInvalidatorContext);
 
     for (const LayoutObject* child = object.slowFirstChild(); child; child = child->nextSibling()) {
         // Column spanners are walked through their placeholders. See below.
         if (child->isColumnSpanAll())
             continue;
         walk(*child, localContext);
     }
 
     if (object.isLayoutMultiColumnSpannerPlaceholder())
         walk(*toLayoutMultiColumnSpannerPlaceholder(object).layoutObjectInFlowThread(), localContext);
 
     if (object.isLayoutPart()) {
         const LayoutPart& layoutPart = toLayoutPart(object);
         Widget* widget = layoutPart.widget();
         if (widget && widget->isFrameView()) {
             localContext.treeBuilderContext.current.paintOffset += layoutPart.replacedContentRect().location() - widget->frameRect().location();
             localContext.treeBuilderContext.current.paintOffset = roundedIntPoint(localContext.treeBuilderContext.current.paintOffset);
             walk(*toFrameView(widget), localContext);
         }
         // TODO(pdr): Investigate RemoteFrameView (crbug.com/579281).
     }
 }
 
 } // namespace blink