Skip paint property update and visual rect update if no geometry change

third_party/WebKit/Source/core/paint/PaintInvalidationCapableScrollableArea.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/PaintInvalidationCapableScrollableArea.h"
 
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutScrollbar.h"
 #include "core/layout/LayoutScrollbarPart.h"
 #include "core/layout/PaintInvalidationState.h"
+#include "core/paint/FindPaintOffsetAndVisualRectNeedingUpdate.h"
 #include "core/paint/ObjectPaintInvalidator.h"
 #include "core/paint/PaintInvalidator.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/graphics/GraphicsLayer.h"
 
 namespace blink {
 
 void PaintInvalidationCapableScrollableArea::willRemoveScrollbar(
     Scrollbar& scrollbar,
     ScrollbarOrientation orientation) {
   if (!scrollbar.isCustomScrollbar() &&
       !(orientation == HorizontalScrollbar ? layerForHorizontalScrollbar()
                                            : layerForVerticalScrollbar()))
     ObjectPaintInvalidator(*layoutBox())
         .slowSetPaintingLayerNeedsRepaintAndInvalidateDisplayItemClient(
             scrollbar, PaintInvalidationScroll);
 
   ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
 }
 
 static LayoutRect scrollControlVisualRect(
     const IntRect& scrollControlRect,
     const LayoutBox& box,
-    const PaintInvalidatorContext& context) {
+    const PaintInvalidatorContext& context,
+    const LayoutRect& previousVisualRect) {
   LayoutRect visualRect(scrollControlRect);
+#if DCHECK_IS_ON()
+  FindVisualRectNeedingUpdateScope finder(box, context, previousVisualRect,
+                                          visualRect);
+#endif
+  if (!context.needsVisualRectUpdate(box))
+    return previousVisualRect;
+
   // No need to apply any paint offset. Scroll controls paint in a different
   // transform space than their contained box (the scrollbarPaintOffset
   // transform node).
   if (!visualRect.isEmpty() &&
       !RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     // PaintInvalidatorContext::mapLocalRectToPaintInvalidationBacking() treats
     // the rect as in flipped block direction, but scrollbar controls don't
     // flip for block direction, so flip here to undo the flip in the function.
     box.flipForWritingMode(visualRect);
     context.mapLocalRectToVisualRectInBacking(box, visualRect);
@@ skipping 26 matching lines @@
 static LayoutRect invalidatePaintOfScrollbarIfNeeded(
     Scrollbar* scrollbar,
     GraphicsLayer* graphicsLayer,
     bool& previouslyWasOverlay,
     const LayoutRect& previousVisualRect,
     bool needsPaintInvalidationArg,
     LayoutBox& box,
     const PaintInvalidatorContext& context) {
   bool isOverlay = scrollbar && scrollbar->isOverlayScrollbar();
 
+  LayoutRect newVisualRect;
   // Calculate visual rect of the scrollbar, except overlay composited
   // scrollbars because we invalidate the graphics layer only.
-  LayoutRect newVisualRect;
   if (scrollbar && !(graphicsLayer && isOverlay)) {
-    newVisualRect =
-        scrollControlVisualRect(scrollbar->frameRect(), box, context);
+    newVisualRect = scrollControlVisualRect(scrollbar->frameRect(), box,
+                                            context, previousVisualRect);
   }
 
   bool needsPaintInvalidation = needsPaintInvalidationArg;
   if (needsPaintInvalidation && graphicsLayer) {
     // If the scrollbar needs paint invalidation but didn't change location/size
     // or the scrollbar is an overlay scrollbar (visual rect is empty),
     // invalidating the graphics layer is enough (which has been done in
     // ScrollableArea::setScrollbarNeedsPaintInvalidation()).
     // Otherwise invalidatePaintOfScrollControlIfNeeded() below will invalidate
     // the old and new location of the scrollbar on the box's paint invalidation
@@ skipping 52 matching lines @@
       horizontalScrollbar(), layerForHorizontalScrollbar(),
       m_horizontalScrollbarPreviouslyWasOverlay,
       m_horizontalScrollbarVisualRect,
       horizontalScrollbarNeedsPaintInvalidation(), box, context));
   setVerticalScrollbarVisualRect(invalidatePaintOfScrollbarIfNeeded(
       verticalScrollbar(), layerForVerticalScrollbar(),
       m_verticalScrollbarPreviouslyWasOverlay, m_verticalScrollbarVisualRect,
       verticalScrollbarNeedsPaintInvalidation(), box, context));
 
   LayoutRect scrollCornerAndResizerVisualRect =
-      scrollControlVisualRect(scrollCornerAndResizerRect(), box, context);
+      scrollControlVisualRect(scrollCornerAndResizerRect(), box, context,
+                              m_scrollCornerAndResizerVisualRect);
   const LayoutBoxModelObject& paintInvalidationContainer =
       *context.paintInvalidationContainer;
   if (invalidatePaintOfScrollControlIfNeeded(
           scrollCornerAndResizerVisualRect, m_scrollCornerAndResizerVisualRect,
           scrollCornerNeedsPaintInvalidation(), box,
           paintInvalidationContainer)) {
     setScrollCornerAndResizerVisualRect(scrollCornerAndResizerVisualRect);
     if (LayoutScrollbarPart* scrollCorner = this->scrollCorner()) {
       ObjectPaintInvalidator(*scrollCorner)
           .invalidateDisplayItemClientsIncludingNonCompositingDescendants(
@@ skipping 78 matching lines @@
                : UseCounter::ScrollbarUseHorizontalScrollbarTrack);
       break;
     default:
       return;
   }
 
   UseCounter::count(layoutBox()->document(), scrollbarUseUMA);
 }
 
 }  // namespace blink