Index: third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.cpp |
diff --git a/third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.cpp b/third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.cpp |
new file mode 100644 |
index 0000000000000000000000000000000000000000..cb2d9b1158971a96cff76f152a1fb4f90688a073 |
--- /dev/null |
+++ b/third_party/WebKit/Source/platform/graphics/CompositorMutableStateProvider.cpp |
@@ -0,0 +1,43 @@ |
+// Copyright 2016 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/CompositorMutableStateProvider.h" |
+ |
+#include "cc/layers/layer_impl.h" |
+#include "cc/trees/layer_tree_impl.h" |
+#include "platform/graphics/CompositorMutableState.h" |
+#include "platform/graphics/CompositorMutation.h" |
+#include "wtf/PassOwnPtr.h" |
+ |
+namespace blink { |
+ |
+CompositorMutableStateProvider::CompositorMutableStateProvider(cc::LayerTreeImpl* state, CompositorMutations* mutations) |
+ : m_state(state) |
+ , m_mutations(mutations) |
+{ |
+} |
+ |
+CompositorMutableStateProvider::~CompositorMutableStateProvider() {} |
+ |
+PassOwnPtr<CompositorMutableState> |
+CompositorMutableStateProvider::getMutableStateFor(uint64_t element_id) |
+{ |
+ cc::LayerTreeImpl::ElementLayers layers = m_state->GetMutableLayers(element_id); |
+ |
+ if (!layers.main && !layers.scroll) |
+ return nullptr; |
+ |
+ // Ensure that we have an entry in the map for |element_id| but do as few |
+ // allocations and queries as possible. This will update the map only if we |
+ // have not added a value for |element_id|. |
+ auto result = m_mutations->map.add(element_id, nullptr); |
+ |
+ // Only if this is a new entry do we want to allocate a new mutation. |
+ if (result.isNewEntry) |
+ result.storedValue->value = adoptPtr(new CompositorMutation); |
+ |
+ return adoptPtr(new CompositorMutableState(result.storedValue->value.get(), layers.main, layers.scroll)); |
+} |
+ |
+} // namespace blink |