external_view_embedder_2.h

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// 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_SHELL_PLATFORM_ANDROID_EXTERNAL_VIEW_EMBEDDER_EXTERNAL_VIEW_EMBEDDER_2_H_
#define FLUTTER_SHELL_PLATFORM_ANDROID_EXTERNAL_VIEW_EMBEDDER_EXTERNAL_VIEW_EMBEDDER_2_H_
 
#include <atomic>
#include <unordered_map>
 
#include "flutter/common/task_runners.h"
#include "flutter/flow/embedded_views.h"
#include "flutter/shell/platform/android/context/android_context.h"
#include "flutter/shell/platform/android/external_view_embedder/surface_pool.h"
#include "flutter/shell/platform/android/jni/platform_view_android_jni.h"
#include "flutter/shell/platform/android/surface/android_surface.h"
#include "third_party/abseil-cpp/absl/container/flat_hash_set.h"
 
namespace flutter {
 
//------------------------------------------------------------------------------
/// Allows to embed Android views into a Flutter application.
///
/// This class calls Java methods via |PlatformViewAndroidJNI| to manage the
/// lifecycle of the Android view corresponding to |flutter::PlatformViewLayer|.
///
/// It also orchestrates overlay surfaces. These are Android views
/// that render above (by Z order) the Android view corresponding to
/// |flutter::PlatformViewLayer|.
///
/// This implementation of the external view embedder is designed only to use
/// HC++ mode. Mixing old HC modes is not supported, but either of the texture
/// composition based platform views can be used with either mode.
class AndroidExternalViewEmbedder2 final : public ExternalViewEmbedder {
 public:
  AndroidExternalViewEmbedder2(
      const AndroidContext& android_context,
      std::shared_ptr<PlatformViewAndroidJNI> jni_facade,
      std::shared_ptr<AndroidSurfaceFactory> surface_factory,
      const TaskRunners& task_runners);
 
  // |ExternalViewEmbedder|
  void PrerollCompositeEmbeddedView(
      int64_t view_id,
      std::unique_ptr<flutter::EmbeddedViewParams> params) override;
 
  // |ExternalViewEmbedder|
  DlCanvas* CompositeEmbeddedView(int64_t view_id) override;
 
  // |ExternalViewEmbedder|
  void SubmitFlutterView(
      int64_t flutter_view_id,
      GrDirectContext* context,
      const std::shared_ptr<impeller::AiksContext>& aiks_context,
      std::unique_ptr<SurfaceFrame> frame) override;
 
  // |ExternalViewEmbedder|
  PostPrerollResult PostPrerollAction(
      const fml::RefPtr<fml::RasterThreadMerger>& raster_thread_merger)
      override;
 
  // |ExternalViewEmbedder|
  DlCanvas* GetRootCanvas() override;
 
  // |ExternalViewEmbedder|
  void BeginFrame(GrDirectContext* context,
                  const fml::RefPtr<fml::RasterThreadMerger>&
                      raster_thread_merger) override;
 
  // |ExternalViewEmbedder|
  void PrepareFlutterView(DlISize frame_size,
                          double device_pixel_ratio) override;
 
  // |ExternalViewEmbedder|
  void CancelFrame() override;
 
  // |ExternalViewEmbedder|
  void EndFrame(bool should_resubmit_frame,
                const fml::RefPtr<fml::RasterThreadMerger>&
                    raster_thread_merger) override;
 
  // |ExternalViewEmbedder|
  bool SupportsDynamicThreadMerging() override;
 
  // |ExternalViewEmbedder|
  void Teardown() override;
 
  // Gets the rect based on the device pixel ratio of a platform view displayed
  // on the screen.
  static DlRect GetViewRect(
      int64_t view_id,
      const std::unordered_map<int64_t, EmbeddedViewParams>& view_params);
 
 private:
  // The number of frames the rasterizer task runner will continue
  // to run on the platform thread after no platform view is rendered.
  //
  // Note: this is an arbitrary number that attempts to account for cases
  // where the platform view might be momentarily off the screen.
  static const int kDefaultMergedLeaseDuration = 10;
 
  // Provides metadata to the Android surfaces.
  const AndroidContext& android_context_;
 
  // Allows to call methods in Java.
  const std::shared_ptr<PlatformViewAndroidJNI> jni_facade_;
 
  // Allows to create surfaces.
  const std::shared_ptr<AndroidSurfaceFactory> surface_factory_;
 
  // Holds surfaces. Allows to recycle surfaces or allocate new ones.
  const std::unique_ptr<SurfacePool> surface_pool_;
 
  // The task runners.
  const TaskRunners task_runners_;
 
  // If the overlay layer is currently shown.
  std::atomic_bool overlay_layer_is_shown_{false};
 
  // The size of the root canvas.
  DlISize frame_size_;
 
  // The pixel ratio used to determinate the size of a platform view layer
  // relative to the device layout system.
  double device_pixel_ratio_;
 
  // The order of composition. Each entry contains a unique id for the platform
  // view.
  std::vector<int64_t> composition_order_;
 
  // The |EmbedderViewSlice| implementation keyed off the platform view id,
  // which contains any subsequent operations until the next platform view or
  // the end of the last leaf node in the layer tree.
  std::unordered_map<int64_t, std::unique_ptr<EmbedderViewSlice>> slices_;
 
  // The params for a platform view, which contains the size, position and
  // mutation stack.
  std::unordered_map<int64_t, EmbeddedViewParams> view_params_;
 
  // The set of platform views that were visible in the last frame.
  absl::flat_hash_set<int64_t> views_visible_last_frame_;
 
  // Destroys the surfaces created from the surface factory.
  // This method schedules a task on the platform thread, and waits for
  // the task until it completes.
  void DestroySurfaces();
 
  // Resets the state.
  void Reset();
 
  // Whether the layer tree in the current frame has platform layers.
  bool FrameHasPlatformLayers();
 
  // Shows the overlay layer if it has content and the previous frame did not.
  void ShowOverlayLayerIfNeeded();
 
  // Hides the overlay layer if it does not have content and the previous
  // frame did have content.
  void HideOverlayLayerIfNeeded();
};
 
}  // namespace flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_ANDROID_EXTERNAL_VIEW_EMBEDDER_EXTERNAL_VIEW_EMBEDDER_2_H_