Fix high FPS screen flicker of Platform Views when using ImageReaderPlatformViewRenderTarget (flutter#46724)

The root bug (b/300627634) was that we were holding onto HardwareBuffers
after the owning Image was closed. This CL refactors the C++ code to
properly hold a reference to the Image until it is safe to dispose of.

This CL also refactors the Impeller GL and Skia GL code paths to share
more code.

Author: johnmccutchan

shell/platform/android/hardware_buffer_external_texture.cc

@@ -3,6 +3,8 @@
 
 #include <android/hardware_buffer_jni.h>
 #include <android/sensor.h>
+
+#include "flutter/shell/platform/android/jni/platform_view_android_jni.h"
 #include "flutter/shell/platform/android/ndk_helpers.h"
 
 namespace flutter {
@@ -23,6 +25,7 @@ void HardwareBufferExternalTexture::Paint(PaintContext& context,
   if (state_ == AttachmentState::kDetached) {
     return;
   }
+  Attach(context);
   const bool should_process_frame =
       (!freeze && new_frame_ready_) || dl_image_ == nullptr;
   if (should_process_frame) {
@@ -39,7 +42,7 @@ void HardwareBufferExternalTexture::Paint(PaintContext& context,
         flutter::DlCanvas::SrcRectConstraint::kStrict  // enforce edges
     );
   } else {
-    FML_LOG(WARNING)
+    FML_LOG(ERROR)
         << "No DlImage available for HardwareBufferExternalTexture to paint.";
   }
 }
@@ -57,53 +60,56 @@ void HardwareBufferExternalTexture::OnGrContextCreated() {
   state_ = AttachmentState::kUninitialized;
 }
 
-AHardwareBuffer* HardwareBufferExternalTexture::GetLatestHardwareBuffer() {
+// Implementing flutter::ContextListener.
+void HardwareBufferExternalTexture::OnGrContextDestroyed() {
+  if (state_ == AttachmentState::kAttached) {
+    dl_image_.reset();
+    Detach();
+  }
+  state_ = AttachmentState::kDetached;
+}
+
+JavaLocalRef HardwareBufferExternalTexture::AcquireLatestImage() {
   JNIEnv* env = fml::jni::AttachCurrentThread();
   FML_CHECK(env != nullptr);
 
   // ImageTextureEntry.acquireLatestImage.
   JavaLocalRef image_java = jni_facade_->ImageTextureEntryAcquireLatestImage(
       JavaLocalRef(image_texture_entry_));
-  if (image_java.obj() == nullptr) {
-    return nullptr;
-  }
+  return image_java;
+}
 
-  // Image.getHardwareBuffer.
-  JavaLocalRef hardware_buffer_java =
-      jni_facade_->ImageGetHardwareBuffer(image_java);
-  if (hardware_buffer_java.obj() == nullptr) {
-    jni_facade_->ImageClose(image_java);
-    return nullptr;
+void HardwareBufferExternalTexture::CloseImage(
+    const fml::jni::JavaRef<jobject>& image) {
+  if (image.obj() == nullptr) {
+    return;
   }
+  jni_facade_->ImageClose(JavaLocalRef(image));
+}
 
-  // Convert into NDK HardwareBuffer.
-  AHardwareBuffer* latest_hardware_buffer =
-      NDKHelpers::AHardwareBuffer_fromHardwareBuffer(
-          env, hardware_buffer_java.obj());
-  if (latest_hardware_buffer == nullptr) {
-    jni_facade_->HardwareBufferClose(hardware_buffer_java);
-    jni_facade_->ImageClose(image_java);
-    return nullptr;
+void HardwareBufferExternalTexture::CloseHardwareBuffer(
+    const fml::jni::JavaRef<jobject>& hardware_buffer) {
+  if (hardware_buffer.obj() == nullptr) {
+    return;
   }
-
-  // Keep hardware buffer alive.
-  NDKHelpers::AHardwareBuffer_acquire(latest_hardware_buffer);
-
-  // Now that we have referenced the native hardware buffer, close the Java
-  // Image and HardwareBuffer objects.
-  jni_facade_->HardwareBufferClose(hardware_buffer_java);
-  jni_facade_->ImageClose(image_java);
-
-  return latest_hardware_buffer;
+  jni_facade_->HardwareBufferClose(JavaLocalRef(hardware_buffer));
 }
 
-// Implementing flutter::ContextListener.
-void HardwareBufferExternalTexture::OnGrContextDestroyed() {
-  if (state_ == AttachmentState::kAttached) {
-    dl_image_.reset();
-    Detach();
+JavaLocalRef HardwareBufferExternalTexture::HardwareBufferFor(
+    const fml::jni::JavaRef<jobject>& image) {
+  if (image.obj() == nullptr) {
+    return JavaLocalRef();
   }
-  state_ = AttachmentState::kDetached;
+  // Image.getHardwareBuffer.
+  return jni_facade_->ImageGetHardwareBuffer(JavaLocalRef(image));
+}
+
+AHardwareBuffer* HardwareBufferExternalTexture::AHardwareBufferFor(
+    const fml::jni::JavaRef<jobject>& hardware_buffer) {
+  JNIEnv* env = fml::jni::AttachCurrentThread();
+  FML_CHECK(env != nullptr);
+  return NDKHelpers::AHardwareBuffer_fromHardwareBuffer(env,
+                                                        hardware_buffer.obj());
 }
 
 }  // namespace flutter

shell/platform/android/hardware_buffer_external_texture.h

@@ -7,6 +7,7 @@
 
 #include "flutter/common/graphics/texture.h"
 #include "flutter/fml/logging.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>
@@ -20,10 +21,11 @@ class HardwareBufferExternalTexture : public flutter::Texture {
  public:
   explicit HardwareBufferExternalTexture(
       int64_t id,
-      const fml::jni::ScopedJavaGlobalRef<jobject>&
-          hardware_buffer_texture_entry,
+      const fml::jni::ScopedJavaGlobalRef<jobject>& image_texture_entry,
       const std::shared_ptr<PlatformViewAndroidJNI>& jni_facade);
 
+  virtual ~HardwareBufferExternalTexture() = default;
+
   // |flutter::Texture|.
   void Paint(PaintContext& context,
              const SkRect& bounds,
@@ -43,10 +45,16 @@ class HardwareBufferExternalTexture : public flutter::Texture {
   void OnGrContextDestroyed() override;
 
  protected:
-  virtual void ProcessFrame(PaintContext& context, const SkRect& bounds) = 0;
+  virtual void Attach(PaintContext& context) = 0;
   virtual void Detach() = 0;
+  virtual void ProcessFrame(PaintContext& context, const SkRect& bounds) = 0;
 
-  AHardwareBuffer* GetLatestHardwareBuffer();
+  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_;