Add support for drawing video onto a Java ByteBuffer

remoting/client/jni/jni_frame_consumer.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/client/jni/jni_frame_consumer.h"
+
+#include "base/android/jni_android.h"
+#include "base/logging.h"
+#include "base/synchronization/waitable_event.h"
+#include "remoting/client/frame_producer.h"
+#include "remoting/client/jni/chromoting_jni.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
+
+namespace {
+
+// Allocates its buffer within a Java direct byte buffer, where it can be
+// accessed by both native and managed code.
+class DirectDesktopFrame : public webrtc::BasicDesktopFrame {
+ public:
+  DirectDesktopFrame(int width, int height);
+
+  virtual ~DirectDesktopFrame();
+
+  jobject buffer() const {
+    return buffer_;
+  }
+
+ private:
+  jobject buffer_;
+};
+
+DirectDesktopFrame::DirectDesktopFrame(int width, int height)
+    : webrtc::BasicDesktopFrame(webrtc::DesktopSize(width, height)) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  buffer_ = env->NewDirectByteBuffer(data(), stride()*height);
+}
+
+DirectDesktopFrame::~DirectDesktopFrame() {}
+
+}  // namespace
+
+namespace remoting {
+
+JniFrameConsumer::JniFrameConsumer()
+    : provide_buffer_(true),

[Wez, 2013/07/22 19:41:28]

nit: This should be e.g. |shutting_down_| or |in_dtor_| to more precisely
describe what it means, since the code assumes it's only false during shutdown.

[solb, 2013/07/22 22:49:32]

Done.

+      frame_producer_(NULL) {
+}
+
+JniFrameConsumer::~JniFrameConsumer() {
+  // Stop giving the producer a buffer to work with.
+  provide_buffer_ = false;
+
+  // Don't destroy the object until we've deleted the buffer.
+  base::WaitableEvent done_event(true, false);
+  frame_producer_->RequestReturnBuffers(
+      base::Bind(&base::WaitableEvent::Signal, base::Unretained(&done_event)));
+  done_event.Wait();
+}
+
+void JniFrameConsumer::set_frame_producer(FrameProducer* producer) {
+  frame_producer_ = producer;
+}
+
+void JniFrameConsumer::ApplyBuffer(const SkISize& view_size,
+                                   const SkIRect& clip_area,
+                                   webrtc::DesktopFrame* buffer,
+                                   const SkRegion& region) {
+  DCHECK(ChromotingJni::GetInstance()->
+      display_task_runner()->BelongsToCurrentThread());
+
+  ChromotingJni::GetInstance()->RedrawCanvas();
+
+  if (view_size.width() > view_size_.width() ||
+      view_size.height() > view_size_.height()) {
+    LOG(INFO) << "Existing buffer is too small";
+    view_size_ = view_size;
+    delete buffer;
+    AllocateBuffer();
+  }
+
+  // Supply |frame_producer_| with a buffer to render the next frame into.
+  if (provide_buffer_)

[Wez, 2013/07/22 19:41:28]

If |provide_buffer_| is false _and_ the view hasn't got bigger then you'll
neither delete nor pass back |buffer|, will you?

[solb, 2013/07/22 22:49:32]

Oops! Thanks for catching that.

+    frame_producer_->DrawBuffer(buffer);
+}
+
+void JniFrameConsumer::ReturnBuffer(webrtc::DesktopFrame* buffer) {
+  DCHECK(ChromotingJni::GetInstance()->
+      display_task_runner()->BelongsToCurrentThread());
+  LOG(INFO) << "Returning image buffer";
+  delete buffer;
+}
+
+void JniFrameConsumer::SetSourceSize(const SkISize& source_size,
+                                     const SkIPoint& dpi) {
+  DCHECK(ChromotingJni::GetInstance()->
+      display_task_runner()->BelongsToCurrentThread());
+
+  // We currently render the desktop 1:1 and perform pan/zoom scaling
+  // and cropping on the managed canvas.
+  view_size_ = source_size;
+  clip_area_ = SkIRect::MakeSize(view_size_);
+  frame_producer_->SetOutputSizeAndClip(view_size_, clip_area_);
+
+  // Unless being destructed, allocate buffer and start drawing frames onto it.
+  frame_producer_->RequestReturnBuffers(base::Bind(
+      &JniFrameConsumer::AllocateBuffer, base::Unretained(this)));
+}
+
+void JniFrameConsumer::AllocateBuffer() {
+  // Only do anything if we're not being destructed.
+  if (provide_buffer_) {
+    if (!ChromotingJni::GetInstance()->
+        display_task_runner()->BelongsToCurrentThread()) {
+      ChromotingJni::GetInstance()->display_task_runner()->PostTask(FROM_HERE,
+          base::Bind(&JniFrameConsumer::AllocateBuffer,
+                     base::Unretained(this)));
+      return;
+    }
+
+    DirectDesktopFrame* buffer = new DirectDesktopFrame(view_size_.width(),
+                                                        view_size_.height());
+
+    // Update Java's reference to the buffer and record of its dimensions.
+    ChromotingJni::GetInstance()->UpdateImageBuffer(
+        view_size_.width(),
+        view_size_.height(),
+        buffer->buffer());
+
+    frame_producer_->DrawBuffer(buffer);
+  }
+}
+
+}  // namespace remoting