image_external_texture.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_IMAGE_EXTERNAL_TEXTURE_H_
#define FLUTTER_SHELL_PLATFORM_ANDROID_IMAGE_EXTERNAL_TEXTURE_H_
 
#include "flutter/common/graphics/texture.h"
#include "flutter/fml/logging.h"
#include "flutter/shell/platform/android/image_lru.h"
#include "flutter/shell/platform/android/jni/platform_view_android_jni.h"
#include "flutter/shell/platform/android/platform_view_android_jni_impl.h"
 
#include <android/hardware_buffer.h>
#include <android/hardware_buffer_jni.h>
 
namespace flutter {
 
//------------------------------------------------------------------------------
/// @brief      External texture peered to a sequence of
///             android.hardware.HardwareBuffers.
///
///             Android Hardware Buffers are available on newer versions of
///             Android (API 29 and above).
///
///             This is an abstract base class and graphics packages provide
///             concrete implementations of this class that bind hardware
///             buffers to their own package-specific implementations of
///             textures (SkImages, impeller::Texture, etc...).
///
///             Android Hardware Buffers allow binding to both OpenGL and Vulkan
///             client-rendering APIs in a zero copy manner. Because of this
///             graphics packages that support OpenGL and Vulkan can have
///             multiple subclasses for each supported client-rendering API.
///
class ImageExternalTexture : public flutter::Texture {
 public:
  /// Whether the last image should be reset when the context is destroyed.
  enum class ImageLifecycle { kReset, kKeepAlive };
 
  explicit ImageExternalTexture(
      int64_t id,
      const fml::jni::ScopedJavaGlobalRef<jobject>& image_texture_entry,
      const std::shared_ptr<PlatformViewAndroidJNI>& jni_facade,
      ImageLifecycle lifecycle);
 
  // |flutter::Texture|
  virtual ~ImageExternalTexture();
 
 protected:
  //----------------------------------------------------------------------------
  /// @brief      Subclasses override this method to bind the latest
  ///             representation of the hardware buffer wrapped by this texture
  ///             instance to their own graphics package specific texture
  ///             classes (SkImage, impeller::Texture, etc...).
  ///
  ///             After a call to this method, attachment state of this instance
  ///             must be kAttached. That is the responsibility of the subclass.
  ///
  /// @param      context  The context
  /// @param[in]  bounds   The bounds
  ///
  virtual void ProcessFrame(PaintContext& context, const SkRect& bounds) = 0;
 
  virtual void Attach(PaintContext& context) = 0;
 
  virtual void Detach() = 0;
 
  JavaLocalRef AcquireLatestImage();
 
  void CloseImage(const fml::jni::JavaRef<jobject>& image);
 
  JavaLocalRef HardwareBufferFor(const fml::jni::JavaRef<jobject>& image);
 
  void CloseHardwareBuffer(const fml::jni::JavaRef<jobject>& hardware_buffer);
 
  AHardwareBuffer* AHardwareBufferFor(
      const fml::jni::JavaRef<jobject>& hardware_buffer);
 
  fml::jni::ScopedJavaGlobalRef<jobject> image_texture_entry_;
  std::shared_ptr<PlatformViewAndroidJNI> jni_facade_;
 
  enum class AttachmentState { kUninitialized, kAttached, kDetached };
  AttachmentState state_ = AttachmentState::kUninitialized;
  sk_sp<flutter::DlImage> dl_image_;
  ImageLRU image_lru_ = ImageLRU();
 
 private:
  // |flutter::Texture|.
  void Paint(PaintContext& context,
             const DlRect& bounds,
             bool freeze,
             const DlImageSampling sampling) override;
 
  // |flutter::Texture|.
  void MarkNewFrameAvailable() override;
 
  // |flutter::Texture|
  void OnTextureUnregistered() override;
 
  // |flutter::ContextListener|
  void OnGrContextCreated() override;
 
  // |flutter::ContextListener|
  void OnGrContextDestroyed() override;
 
  const ImageLifecycle texture_lifecycle_;
  FML_DISALLOW_COPY_AND_ASSIGN(ImageExternalTexture);
};
 
}  // namespace flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_ANDROID_IMAGE_EXTERNAL_TEXTURE_H_