impeller/entity/render_target_cache.h

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef FLUTTER_IMPELLER_ENTITY_RENDER_TARGET_CACHE_H_
#define FLUTTER_IMPELLER_ENTITY_RENDER_TARGET_CACHE_H_

#include "impeller/renderer/render_target.h"

namespace impeller {

/// @brief An implementation of the [RenderTargetAllocator] that caches all
///        allocated texture data for one frame.
///
///        Any textures unused after a frame are immediately discarded.
class RenderTargetCache : public RenderTargetAllocator {
 public:
  explicit RenderTargetCache(std::shared_ptr<Allocator> allocator);

  ~RenderTargetCache() = default;

  // |RenderTargetAllocator|
  void Start() override;

  // |RenderTargetAllocator|
  void End() override;

  // |RenderTargetAllocator|
  std::shared_ptr<Texture> CreateTexture(
      const TextureDescriptor& desc) override;

  // visible for testing.
  size_t CachedTextureCount() const;

 private:
  struct TextureData {
    bool used_this_frame;
    std::shared_ptr<Texture> texture;
  };

  std::vector<TextureData> texture_data_;

  RenderTargetCache(const RenderTargetCache&) = delete;

  RenderTargetCache& operator=(const RenderTargetCache&) = delete;

 public:
  /// Visible for testing.
  std::vector<TextureData>::const_iterator GetTextureDataBegin() const {
    return texture_data_.begin();
  }

  /// Visible for testing.
  std::vector<TextureData>::const_iterator GetTextureDataEnd() const {
    return texture_data_.end();
  }
};

}  // namespace impeller

#endif  // FLUTTER_IMPELLER_ENTITY_RENDER_TARGET_CACHE_H_