PaintChunk::id

third_party/WebKit/Source/platform/graphics/paint/PaintChunker.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 "platform/graphics/paint/PaintChunker.h"
 
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 PaintChunker::PaintChunker()
 {
 }
 
 PaintChunker::~PaintChunker()
 {
 }
 
-void PaintChunker::updateCurrentPaintChunkProperties(const PaintChunkProperties& properties)
+void PaintChunker::updateCurrentPaintChunkProperties(const DisplayItem::Id* chunkId, const PaintChunkProperties& properties)
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
+    m_currentChunkId = WTF::nullopt;
+    if (chunkId)
+        m_currentChunkId.emplace(*chunkId);
     m_currentProperties = properties;
 }
 
-void PaintChunker::incrementDisplayItemIndex(ItemBehavior behavior)
+void PaintChunker::incrementDisplayItemIndex(const DisplayItem& item)
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
+    ItemBehavior behavior;
+    Optional<DisplayItem::Id> newChunkId;
+    if (DisplayItem::isForeignLayerType(item.getType())) {
+        behavior = RequiresSeparateChunk;
+        // Use null chunkId if we are skipping cache, so that the chunk will not
+        // match any old chunk and will be treated as brand new.
+        if (!item.skippedCache())
+            newChunkId.emplace(item.getId());
+
+        // Clear m_currentChunkId so that any display items after the foreign layer
+        // without a new chunk id will be treated as having no id to avoid the chunk
+        // from using the same id as the chunk before the foreign layer chunk.
+        m_currentChunkId = WTF::nullopt;
+    } else {
+        behavior = DefaultBehavior;
+        if (!item.skippedCache() && m_currentChunkId)
+            newChunkId.emplace(*m_currentChunkId);
+    }
+
     if (m_chunks.isEmpty()) {
-        PaintChunk newChunk(0, 1, m_currentProperties);
+        PaintChunk newChunk(0, 1, newChunkId ? &*newChunkId : nullptr, m_currentProperties);
         m_chunks.append(newChunk);
         m_chunkBehavior.append(behavior);
         return;
     }
 
     auto& lastChunk = m_chunks.last();
     bool canContinueChunk = m_currentProperties == lastChunk.properties
         && behavior != RequiresSeparateChunk
         && m_chunkBehavior.last() != RequiresSeparateChunk;
     if (canContinueChunk) {
         lastChunk.endIndex++;
         return;
     }
 
-    PaintChunk newChunk(lastChunk.endIndex, lastChunk.endIndex + 1, m_currentProperties);
+    PaintChunk newChunk(lastChunk.endIndex, lastChunk.endIndex + 1, newChunkId ? &*newChunkId : nullptr, m_currentProperties);

[pdr., 2016/07/13 17:49:52]

&*newChunkId -> newChunkId?

[Xianzhu, 2016/07/13 18:45:50]

This is to get a 'const DisplayItem::Id*'. Actually I want Optional::get() which
is not available.

Changed the parameter type to "const Optional<DisplayItem::Id>&" to avoid the
above weirdness.

[Xianzhu, 2016/07/13 19:06:02]

Please ignore the last sentence for now. The method has some problems needing
investigation.

[Xianzhu, 2016/07/13 19:15:41]

Some places would look weirder with the "const Optional<DisplayItem::Id>&"
method (e.g. we would need to declare an Optional<DisplayItem::Id> and emplace
it even we do have an id). Let's still review this version.

[pdr., 2016/07/13 23:31:34]

Thanks for the explanation. Looks weird but sounds like the most reasonable
approach.

     m_chunks.append(newChunk);
     m_chunkBehavior.append(behavior);
 }
 
 void PaintChunker::decrementDisplayItemIndex()
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
     ASSERT(!m_chunks.isEmpty());
 
     auto& lastChunk = m_chunks.last();
     if ((lastChunk.endIndex - lastChunk.beginIndex) > 1) {
         lastChunk.endIndex--;
     } else {
         m_chunks.removeLast();
         m_chunkBehavior.removeLast();
     }
 }
 
 void PaintChunker::clear()
 {
     m_chunks.clear();
     m_chunkBehavior.clear();
+    m_currentChunkId = WTF::nullopt;
     m_currentProperties = PaintChunkProperties();
 }
 
 Vector<PaintChunk> PaintChunker::releasePaintChunks()
 {
     Vector<PaintChunk> chunks;
     chunks.swap(m_chunks);
     m_chunkBehavior.clear();
+    m_currentChunkId = WTF::nullopt;
     m_currentProperties = PaintChunkProperties();
     return chunks;
 }
 
 } // namespace blink