Store previous painting clip rects on FragmentData.

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"
@@ skipping 148 matching lines @@
   }
 
   // This code below checks whether any clips have changed that might:
   // (a) invalidate optimizations made for a PaintLayer that supports
   //     subsequence caching, or
   // (b) impact clipping of descendant visual rects.
   if (!paint_layer.SupportsSubsequenceCaching() &&
       !paint_layer.GetLayoutObject().HasClipRelatedProperty())
     return;
 
+  FragmentData* fragment_data = object.GetMutableForPainting().FirstFragment();
+  for (auto& fragment : context.tree_builder_context->fragments) {
+    DCHECK(fragment_data);
+    if (InvalidatePaintLayerOptimizationsForFragment(
+            object, context.ancestor_transformed_or_root_paint_layer, fragment,

[wkorman, 2017/05/01 20:29:24]

I wondered why this member data name was so long and found:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/paint/Pre...

Reading that, it looks like we only ever set and never subsequently read from
PaintLayer.ancestor_overflow_paint_layer. Can it be removed (in separate patch)?

[chrishtr, 2017/05/01 21:43:54]

Removed.

[chrishtr, 2017/05/01 21:54:39]

I was wrong, it is needed. It is set on PaintLayer via
UpdateAncestorOverflowLayer, which is then
used by sticky constraints code.

+            *fragment_data)) {
+      context.paint_invalidator_context.forced_subtree_invalidation_flags |=
+          PaintInvalidatorContext::kForcedSubtreeVisualRectUpdate;
+    }
+    fragment_data = fragment_data->NextFragment();
+  }
+}
+
+bool PrePaintTreeWalk::InvalidatePaintLayerOptimizationsForFragment(
+    const LayoutObject& object,
+    const PaintLayer* ancestor_transformed_or_root_paint_layer,
+    const PaintPropertyTreeBuilderFragmentContext& context,
+    FragmentData& fragment_data) {
+  PaintLayer& paint_layer = *ToLayoutBoxModelObject(object).Layer();
+
   const auto& ancestor =
-      context.ancestor_transformed_or_root_paint_layer->GetLayoutObject();
+      ancestor_transformed_or_root_paint_layer->GetLayoutObject();
   PropertyTreeState ancestor_state = *ancestor.LocalBorderBoxProperties();
 
 #ifdef CHECK_CLIP_RECTS
   auto respect_overflow_clip = kRespectOverflowClip;
 #endif
-  if (context.ancestor_transformed_or_root_paint_layer->GetCompositingState() ==
+  if (ancestor_transformed_or_root_paint_layer->GetCompositingState() ==
       kPaintsIntoOwnBacking) {
     const auto* ancestor_properties = ancestor.PaintProperties();
     if (ancestor_properties && ancestor_properties->OverflowClip()) {
       ancestor_state.SetClip(ancestor_properties->OverflowClip());
 #ifdef CHECK_CLIP_RECTS
       respect_overflow_clip = kIgnoreOverflowClip;
 #endif
     }
   }
 
 #ifdef CHECK_CLIP_RECTS
   const auto& old_clip_rects =
       paint_layer.Clipper(PaintLayer::kDoNotUseGeometryMapper)
-          .PaintingClipRects(context.ancestor_transformed_or_root_paint_layer,
+          .PaintingClipRects(ancestor_transformed_or_root_paint_layer,
                              respect_overflow_clip, LayoutSize());
 #endif
 
   const LayoutPoint& ancestor_paint_offset =
-      context.ancestor_transformed_or_root_paint_layer->GetLayoutObject()
-          .PaintOffset();
+      ancestor_transformed_or_root_paint_layer->GetLayoutObject().PaintOffset();
 
   // TODO(chrishtr): generalize this for multicol.
-  const auto* effect =
-      context.tree_builder_context->fragments[0].current_effect;
+  const auto* effect = context.current_effect;
   auto overflow_clip_rect = ComputeClipRectForContext(
-      context.tree_builder_context->fragments[0].current, effect,
-      ancestor_state, ancestor_paint_offset);
+      context.current, effect, ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(overflow_clip_rect == old_clip_rects.OverflowClipRect().Rect())
       << " new=" << overflow_clip_rect.ToString()
       << " old=" << old_clip_rects.OverflowClipRect().Rect().ToString();
 #endif
 
   auto fixed_clip_rect = ComputeClipRectForContext(
-      context.tree_builder_context->fragments[0].fixed_position, effect,
-      ancestor_state, ancestor_paint_offset);
+      context.fixed_position, effect, ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(fixed_clip_rect == old_clip_rects.FixedClipRect().Rect())
       << " new=" << fixed_clip_rect.ToString()
       << " old=" << old_clip_rects.FixedClipRect().Rect().ToString();
 #endif
 
   auto pos_clip_rect = ComputeClipRectForContext(
-      context.tree_builder_context->fragments[0].absolute_position, effect,
-      ancestor_state, ancestor_paint_offset);
+      context.absolute_position, effect, ancestor_state, ancestor_paint_offset);
 #ifdef CHECK_CLIP_RECTS
   CHECK(pos_clip_rect == old_clip_rects.PosClipRect().Rect())
       << " new=" << pos_clip_rect.ToString()
       << " old=" << old_clip_rects.PosClipRect().Rect().ToString();
 #endif
 
-  const auto* previous_clip_rects = paint_layer.PreviousPaintingClipRects();
+  const auto* previous_clip_rects = fragment_data.PreviousPaintingClipRects();
   if (!previous_clip_rects ||
       overflow_clip_rect != previous_clip_rects->OverflowClipRect().Rect() ||
       fixed_clip_rect != previous_clip_rects->FixedClipRect().Rect() ||
       pos_clip_rect != previous_clip_rects->PosClipRect().Rect()) {
     RefPtr<ClipRects> clip_rects = ClipRects::Create();
     clip_rects->SetOverflowClipRect(overflow_clip_rect);
     clip_rects->SetFixedClipRect(fixed_clip_rect);
     clip_rects->SetPosClipRect(pos_clip_rect);
-    paint_layer.SetPreviousPaintingClipRects(*clip_rects);
+    fragment_data.SetPreviousPaintingClipRects(*clip_rects);
 
     paint_layer.SetNeedsRepaint();
     paint_layer.SetPreviousPaintPhaseDescendantOutlinesEmpty(false);
     paint_layer.SetPreviousPaintPhaseFloatEmpty(false);
     paint_layer.SetPreviousPaintPhaseDescendantBlockBackgroundsEmpty(false);
     // All subsequences which are contained below this paintLayer must also
     // be checked.
-    context.paint_invalidator_context.forced_subtree_invalidation_flags |=
-        PaintInvalidatorContext::kForcedSubtreeVisualRectUpdate;
+    return true;
   }
+  return false;
 }
 
 bool PrePaintTreeWalk::NeedsTreeBuilderContextUpdate(
     const FrameView& frame_view,
     const PrePaintTreeWalkContext& context) {
   return frame_view.NeedsPaintPropertyUpdate() ||
          (frame_view.GetLayoutView() &&
           NeedsTreeBuilderContextUpdate(*frame_view.GetLayoutView(), context));
 }
 
 bool PrePaintTreeWalk::NeedsTreeBuilderContextUpdate(
     const LayoutObject& object,
     const PrePaintTreeWalkContext& parent_context) {
   return object.NeedsPaintPropertyUpdate() ||
          object.DescendantNeedsPaintPropertyUpdate() ||
          (parent_context.tree_builder_context &&
           parent_context.tree_builder_context->force_subtree_update) ||
          // If the object needs visual rect update, we should update tree
          // builder context which is needed by visual rect update.
          parent_context.paint_invalidator_context.NeedsVisualRectUpdate(object);
 }
 
+void PrePaintTreeWalk::ClearPreviousPaintingClipRectsForTesting(
+    const LayoutObject& object) {
+  object.GetMutableForPainting()
+      .FirstFragment()
+      ->ClearPreviousPaintingClipRects();
+}
+
 void PrePaintTreeWalk::Walk(const LayoutObject& object,
                             const PrePaintTreeWalkContext& parent_context) {
   // Early out from the tree walk if possible.
   bool needs_tree_builder_context_update =
       this->NeedsTreeBuilderContextUpdate(object, parent_context);
   if (!needs_tree_builder_context_update &&
       !object.ShouldCheckForPaintInvalidation())
     return;
 
   PrePaintTreeWalkContext context(parent_context,
@@ skipping 40 matching lines @@
       }
       Walk(*frame_view, context);
     }
     // TODO(pdr): Investigate RemoteFrameView (crbug.com/579281).
   }
 
   object.GetMutableForPainting().ClearPaintFlags();
 }
 
 }  // namespace blink