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56 lines
1.6 KiB
C++
56 lines
1.6 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_SHELL_COMMON_LAYER_TREE_HOLDER_H_
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#define FLUTTER_SHELL_COMMON_LAYER_TREE_HOLDER_H_
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#include <memory>
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#include "flow/layers/layer_tree.h"
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namespace flutter {
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/**
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* @brief Holds the next `flutter::LayerTree` that needs to be rasterized. The
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* accesses to `LayerTreeHolder` are thread safe. This is important as this
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* component is accessed from both the UI and the Raster threads.
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*
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* A typical flow of events through this component would be:
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* 1. `flutter::Animator` pushed a layer tree to be rendered during each
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* `Animator::Render` call.
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* 2. `flutter::Rasterizer::Draw` consumes the pushed layer tree via `Pop`.
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*
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* It is important to note that if a layer tree held by this class is yet to be
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* consumed, it can be overriden by a newer layer tree produced by the
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* `Animator`. The newness of the layer tree is determined by the target time.
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*/
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class LayerTreeHolder {
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public:
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LayerTreeHolder();
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~LayerTreeHolder();
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/**
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* @brief Checks if a layer tree is currently held.
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*
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* @return true is no layer tree is held.
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* @return false if there is a layer tree waiting to be consumed.
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*/
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bool IsEmpty() const;
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[[nodiscard]] std::unique_ptr<LayerTree> Pop();
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void PushIfNewer(std::unique_ptr<LayerTree> proposed_layer_tree);
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private:
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mutable std::mutex layer_tree_mutex;
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std::unique_ptr<LayerTree> layer_tree_;
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FML_DISALLOW_COPY_AND_ASSIGN(LayerTreeHolder);
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};
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}; // namespace flutter
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#endif // FLUTTER_SHELL_COMMON_LAYER_TREE_HOLDER_H_
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