PaintChunk::id

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

Index: third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
index 485ec009c0a5657995fb08d4ac3ed465a753e754..051e55f35aecf3f31059602660aa126f3d2e8ded 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
@@ -16,19 +16,41 @@ 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;

[pdr., 2016/07/14 22:22:06]

For items following a foreign layer, will this lead to one PaintChunk per
display item?

[Xianzhu, 2016/07/14 23:03:24]

No. This will cause the chunk following the foreign layer not to match any
cached chunk. The chunk will be always treated as new (that is, will create a
new composited layer, and need full re-rasterization).

+    } else {
+        behavior = DefaultBehavior;
+        if (!item.skippedCache() && m_currentChunkId)

[pdr., 2016/07/14 22:22:06]

Does this mean that skipping the cache causes one PaintChunk per display item?

[Xianzhu, 2016/07/14 23:03:24]

No. Chunks will be created just as before, but they will have null id so won't
match any cached chunk. The chunk will be always treated as new (that is, will
create a new composited layer, and need full re-rasterization).

+            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;
@@ -43,7 +65,7 @@ void PaintChunker::incrementDisplayItemIndex(ItemBehavior behavior)
         return;
     }
 
-    PaintChunk newChunk(lastChunk.endIndex, lastChunk.endIndex + 1, m_currentProperties);
+    PaintChunk newChunk(lastChunk.endIndex, lastChunk.endIndex + 1, newChunkId ? &*newChunkId : nullptr, m_currentProperties);
     m_chunks.append(newChunk);
     m_chunkBehavior.append(behavior);
 }
@@ -66,6 +88,7 @@ void PaintChunker::clear()
 {
     m_chunks.clear();
     m_chunkBehavior.clear();
+    m_currentChunkId = WTF::nullopt;
     m_currentProperties = PaintChunkProperties();
 }
 
@@ -74,6 +97,7 @@ Vector<PaintChunk> PaintChunker::releasePaintChunks()
     Vector<PaintChunk> chunks;
     chunks.swap(m_chunks);
     m_chunkBehavior.clear();
+    m_currentChunkId = WTF::nullopt;
     m_currentProperties = PaintChunkProperties();
     return chunks;
 }