ScreenCapture for Android phase1, part I

media/capture/content/android/screen_capture_machine_android.cc

+// Copyright 2016 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 "media/capture/content/android/screen_capture_machine_android.h"
+
+#include "base/android/context_utils.h"
+#include "base/android/jni_android.h"
+#include "base/android/scoped_java_ref.h"
+#include "jni/ScreenCapture_jni.h"
+#include "media/base/video_capture_types.h"
+#include "media/base/yuv_convert.h"
+#include "media/capture/content/video_capture_oracle.h"
+#include "third_party/libyuv/include/libyuv.h"
+
+using base::android::AttachCurrentThread;
+
+namespace media {
+
+// static
+bool ScreenCaptureMachineAndroid::RegisterScreenCaptureMachine(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+ScreenCaptureMachineAndroid::ScreenCaptureMachineAndroid() {}
+
+ScreenCaptureMachineAndroid::~ScreenCaptureMachineAndroid() {}
+
+// static
+ScopedJavaLocalRef<jobject>
+ScreenCaptureMachineAndroid::createScreenCaptureMachineAndroid(
+    jlong nativeScreenCaptureMachineAndroid) {
+  return (Java_ScreenCapture_createScreenCaptureMachine(
+      AttachCurrentThread(), base::android::GetApplicationContext(),
+      nativeScreenCaptureMachineAndroid));
+}
+
+void ScreenCaptureMachineAndroid::OnRGBAFrameAvailable(JNIEnv* env,
+                                                       jobject obj,
+                                                       jobject buf,
+                                                       jint width,
+                                                       jint height,
+                                                       jint rowStride,
+                                                       jlong timestamp) {
+  const VideoCaptureOracle::Event event = VideoCaptureOracle::kCompositorUpdate;
+  uint64_t absolute_micro =
+      static_cast<int64>(timestamp / base::Time::kNanosecondsPerMicrosecond);
+  const base::TimeTicks start_time =
+      base::TimeTicks::FromInternalValue(absolute_micro);
+  scoped_refptr<VideoFrame> frame;
+  ThreadSafeCaptureOracle::CaptureFrameCallback capture_frame_cb;
+
+  bool oracle_decision = oracle_proxy_->ObserveEventAndDecideCapture(
+      event, gfx::Rect(), start_time, &frame, &capture_frame_cb);
+
+  if (!oracle_decision)
+    return;
+
+  uint8* source_data =
+      reinterpret_cast<uint8_t*>(env->GetDirectBufferAddress(buf));
+  int source_stride = rowStride;

[mcasas, 2016/05/19 19:11:41]

Why not use |rowStride| directly? Consider renaming
the parameter, if |rowStride| is not to your liking. 

[braveyao, 2016/05/20 22:27:25]

Because the stride might be changed below at l.73.
Any way, refactored both jni interface. Hope that's better.

+
+  // If needed, scale the captured frame to the required size.
+  if (gfx::Size(width, height) != frame->visible_rect().size()) {
+    std::unique_ptr<uint8[]> scaled_frame_data;
+    scaled_frame_data.reset(new uint8[frame->visible_rect().width() *
+                                      frame->visible_rect().height() * 4]);
+    libyuv::ARGBScale(
+        source_data, source_stride, width, height, scaled_frame_data.get(),
+        frame->visible_rect().width() * 4, frame->visible_rect().width(),
+        frame->visible_rect().height(), libyuv::kFilterBilinear);
+    source_data = scaled_frame_data.get();
+    source_stride = frame->visible_rect().width() * 4;
+  }
+
+  DCHECK(frame->format() == PIXEL_FORMAT_I420 ||
+         frame->format() == PIXEL_FORMAT_YV12);
+
+  ConvertRGB32ToYUV(

[mcasas, 2016/05/19 19:11:41]

Why not use libyuv here as well [1] ?

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/libyuv...

[braveyao, 2016/05/20 22:27:25]

Done.

+      source_data, frame->visible_data(VideoFrame::kYPlane),
+      frame->visible_data(VideoFrame::kUPlane),
+      frame->visible_data(VideoFrame::kVPlane), frame->visible_rect().width(),
+      frame->visible_rect().height(), source_stride,
+      frame->stride(VideoFrame::kYPlane), frame->stride(VideoFrame::kUPlane));

[mcasas, 2016/05/19 19:11:41]

It'd be possible that the if{} in l.64-74 would
be executed, leaving the scaled frame in |frame|,
and then we'd still be doing l.79 and overwriting
the previously scaled |frame|, right?

[braveyao, 2016/05/20 22:27:25]

Refactored the processing here. The previous l.64-74 has an issue. Now unified
the two jni interface and reuse the code in a new func.

+
+  // Deliver the populated VideoFrame.
+  capture_frame_cb.Run(frame, start_time, true);
+
+  lastFrame_ = frame;
+}
+
+void ScreenCaptureMachineAndroid::OnI420FrameAvailable(JNIEnv* env,
+                                                       jobject obj,
+                                                       jobject y_buffer,
+                                                       jint y_stride,
+                                                       jobject u_buffer,
+                                                       jint u_stride,
+                                                       jobject v_buffer,
+                                                       jint v_stride,
+                                                       jint width,
+                                                       jint height,
+                                                       jlong timestamp) {
+  const VideoCaptureOracle::Event event = VideoCaptureOracle::kCompositorUpdate;
+  uint64_t absolute_micro =

[mcasas, 2016/05/19 19:11:41]

const

[braveyao, 2016/05/20 22:27:25]

Done.

+      static_cast<int64>(timestamp / base::Time::kNanosecondsPerMicrosecond);
+  const base::TimeTicks start_time =
+      base::TimeTicks::FromInternalValue(absolute_micro);
+  scoped_refptr<VideoFrame> frame;
+  ThreadSafeCaptureOracle::CaptureFrameCallback capture_frame_cb;
+
+  bool oracle_decision = oracle_proxy_->ObserveEventAndDecideCapture(

[mcasas, 2016/05/19 19:11:41]

const? Or fold it into l.114.

[braveyao, 2016/05/20 22:27:26]

Done.

+      event, gfx::Rect(), start_time, &frame, &capture_frame_cb);
+
+  if (!oracle_decision)
+    return;
+
+  uint8 *y_src, *u_src, *v_src;
+  y_src = reinterpret_cast<uint8_t*>(env->GetDirectBufferAddress(y_buffer));
+  CHECK(y_src);
+  u_src = reinterpret_cast<uint8_t*>(env->GetDirectBufferAddress(u_buffer));
+  CHECK(u_src);
+  v_src = reinterpret_cast<uint8_t*>(env->GetDirectBufferAddress(v_buffer));
+  CHECK(v_src);
+
+  // U and V planes have |pixelStride| = 2, unpack them here.
+  int uv_plane_len = (int)env->GetDirectBufferCapacity(u_buffer);
+  for (int index = 0; index * 2 <= uv_plane_len; index++) {
+    u_src[index] = u_src[index * 2];
+    v_src[index] = v_src[index * 2];
+  }
+
+  libyuv::I420Scale(y_src, y_stride, u_src, u_stride, v_src, v_stride, width,
+                    height, frame->visible_data(VideoFrame::kYPlane),
+                    frame->stride(VideoFrame::kYPlane),
+                    frame->visible_data(VideoFrame::kUPlane),
+                    frame->stride(VideoFrame::kUPlane),
+                    frame->visible_data(VideoFrame::kVPlane),
+                    frame->stride(VideoFrame::kVPlane),
+                    frame->visible_rect().width(),
+                    frame->visible_rect().height(), libyuv::kFilterBilinear);
+
+  // Deliver the populated VideoFrame.
+  capture_frame_cb.Run(frame, start_time, true);
+
+  lastFrame_ = frame;
+}
+
+void ScreenCaptureMachineAndroid::OnActivityResult(JNIEnv* env,
+                                                   jobject obj,
+                                                   jboolean result) {
+  if (!result) {
+    oracle_proxy_->ReportError(FROM_HERE, "The user denied screen capture");
+    return;
+  }
+
+  Java_ScreenCapture_startCapture(env, obj);
+}
+
+void ScreenCaptureMachineAndroid::Start(
+    const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
+    const VideoCaptureParams& params,
+    const base::Callback<void(bool)> callback) {
+  DCHECK(oracle_proxy.get());
+  oracle_proxy_ = oracle_proxy;
+
+  j_capture_.Reset(
+      createScreenCaptureMachineAndroid(reinterpret_cast<intptr_t>(this)));
+
+  if (j_capture_.obj() == NULL) {

[mcasas, 2016/05/19 19:11:41]

s/NULL/nullptr/

[braveyao, 2016/05/20 22:27:26]

Done.

+    LOG(ERROR) << "Failed to createScreenCaptureAndroid,"
+                  " Maybe android version is too low";
+    callback.Run(false);
+    return;
+  }
+
+  DCHECK(params.requested_format.frame_size.GetArea() > 0);

[mcasas, 2016/05/19 19:11:41]

No need for |> 0|.

[braveyao, 2016/05/20 22:27:25]

Done.

+  DCHECK(!(params.requested_format.frame_size.width() % 2));
+  DCHECK(!(params.requested_format.frame_size.height() % 2));
+
+  jboolean ret = Java_ScreenCapture_startPrompt(

[mcasas, 2016/05/19 19:11:41]

const

[braveyao, 2016/05/20 22:27:26]

Done.

+      AttachCurrentThread(), j_capture_.obj(),
+      params.requested_format.frame_size.width(),
+      params.requested_format.frame_size.height());
+  if (!ret) {

[mcasas, 2016/05/19 19:11:41]

Substitute l.184-189 with
callback.Run(ret);

[braveyao, 2016/05/20 22:27:26]

Done.

+    callback.Run(false);
+    return;
+  }
+
+  callback.Run(true);
+}
+
+void ScreenCaptureMachineAndroid::Stop(const base::Closure& callback) {
+  Java_ScreenCapture_stopCapture(AttachCurrentThread(), j_capture_.obj());
+
+  callback.Run();
+}
+
+// ScreenCapture on Android works in passive way and there will be no captured
+// frame when there is no update to the screen. When oracle asks capturing for
+// refresh, the cached last frame will be delivered.
+void ScreenCaptureMachineAndroid::MaybeCaptureForRefresh() {
+  if (lastFrame_.get() == NULL)

[mcasas, 2016/05/19 19:11:41]

s/NULL/nullptr/

I think you can also say if(!lastFrame_)...

[braveyao, 2016/05/20 22:27:26]

Done.

+    return;
+
+  const VideoCaptureOracle::Event event = VideoCaptureOracle::kCompositorUpdate;
+  const base::TimeTicks start_time = base::TimeTicks::Now();
+  scoped_refptr<VideoFrame> frame;
+  ThreadSafeCaptureOracle::CaptureFrameCallback capture_frame_cb;
+
+  if (oracle_proxy_->ObserveEventAndDecideCapture(
+          event, gfx::Rect(), start_time, &frame, &capture_frame_cb)) {
+    // Deliver the last VideoFrame.

[mcasas, 2016/05/19 19:11:41]

nit: Suggest something like: 
// Deliver again the last captured VideoFrame.

[braveyao, 2016/05/20 22:27:25]

Done.

+    frame = lastFrame_;
+    capture_frame_cb.Run(frame, start_time, true);
+  }
+}
+
+}  // namespace media