Save previous paint offset in LayoutObject

third_party/WebKit/Source/platform/graphics/paint/DisplayItemList.cpp

 // Copyright 2014 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 "config.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 
 #include "platform/NotImplemented.h"
 #include "platform/TraceEvent.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
@@ skipping 145 matching lines @@
 }
 
 #if ENABLE(ASSERT)
 bool DisplayItemList::paintOffsetWasInvalidated(DisplayItemClient client) const
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled());
     return m_clientsWithPaintOffsetInvalidations.contains(client);
 }
 #endif
 
-void DisplayItemList::recordPaintOffset(DisplayItemClient client, const LayoutPoint& paintOffset)
-{
-    ASSERT(RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled());
-    m_previousPaintOffsets.set(client, paintOffset);
-}
-
-bool DisplayItemList::paintOffsetIsUnchanged(DisplayItemClient client, const LayoutPoint& paintOffset) const
-{
-    ASSERT(RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled());
-    PreviousPaintOffsets::const_iterator it = m_previousPaintOffsets.find(client);
-    if (it == m_previousPaintOffsets.end())
-        return false;
-    return paintOffset == it->value;
-}
-
-void DisplayItemList::removeUnneededPaintOffsetEntries()
-{
-    ASSERT(RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled());
-
-    // This function is only needed temporarily while paint offsets are stored
-    // in a map on the list itself. Because we don't always get notified when
-    // a display item client is removed, we need to infer it to prevent the
-    // paint offset map from growing indefinitely. This is achieved by just
-    // removing any paint offset clients that are no longer in the full list.
-
-    HashSet<DisplayItemClient> paintOffsetClientsToRemove;
-    for (auto& client : m_previousPaintOffsets.keys())
-        paintOffsetClientsToRemove.add(client);
-    for (auto& item : m_currentDisplayItems)
-        paintOffsetClientsToRemove.remove(item.client());
-
-    for (auto& client : paintOffsetClientsToRemove)
-        m_previousPaintOffsets.remove(client);
-}
-
 size_t DisplayItemList::findMatchingItemFromIndex(const DisplayItem::Id& id, const DisplayItemIndicesByClientMap& displayItemIndicesByClient, const DisplayItems& list)
 {
     DisplayItemIndicesByClientMap::const_iterator it = displayItemIndicesByClient.find(id.client);
     if (it == displayItemIndicesByClient.end())
         return kNotFound;
 
     const Vector<size_t>& indices = it->value;
     for (size_t index : indices) {
         const DisplayItem& existingItem = list[index];
         ASSERT(!existingItem.isValid() || existingItem.client() == id.client);
@@ skipping 91 matching lines @@
 #endif
 
     if (m_currentDisplayItems.isEmpty()) {
 #if ENABLE(ASSERT)
         for (const auto& item : m_newDisplayItems)
             ASSERT(!item.isCached());
 #endif
         m_currentDisplayItems.swap(m_newDisplayItems);
         m_validlyCachedClientsDirty = true;
         m_numCachedItems = 0;
-        if (RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled())
-            removeUnneededPaintOffsetEntries();
         return;
     }
 
     updateValidlyCachedClientsIfNeeded();
 
     // Stores indices to valid DrawingDisplayItems in m_currentDisplayItems that have not been matched
     // by CachedDisplayItems during synchronized matching. The indexed items will be matched
     // by later out-of-order CachedDisplayItems in m_newDisplayItems. This ensures that when
     // out-of-order CachedDisplayItems occur, we only traverse at most once over m_currentDisplayItems
     // looking for potential matches. Thus we can ensure that the algorithm runs in linear time.
@@ skipping 61 matching lines @@
 #if ENABLE(ASSERT)
     if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled())
         checkNoRemainingCachedDisplayItems();
 #endif // ENABLE(ASSERT)
 
     m_newDisplayItems.clear();
     m_validlyCachedClientsDirty = true;
     m_currentDisplayItems.swap(updatedList);
     m_numCachedItems = 0;
 
-    if (RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled())
-        removeUnneededPaintOffsetEntries();
-
 #if ENABLE(ASSERT)
     m_clientsWithPaintOffsetInvalidations.clear();
 #endif
 }
 
 size_t DisplayItemList::approximateUnsharedMemoryUsage() const
 {
     size_t memoryUsage = sizeof(*this);
 
     // Memory outside this class due to m_currentDisplayItems.
@@ skipping 179 matching lines @@
 
 void DisplayItemList::replay(GraphicsContext& context)
 {
     TRACE_EVENT0("blink,benchmark", "DisplayItemList::replay");
     ASSERT(m_newDisplayItems.isEmpty());
     for (DisplayItem& displayItem : m_currentDisplayItems)
         displayItem.replay(context);
 }
 
 } // namespace blink