[Chromoting] Implement GlRenderer

remoting/client/gl_renderer.h

+// 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.
+
+#ifndef REMOTING_CLIENT_GL_RENDERER_H_
+#define REMOTING_CLIENT_GL_RENDERER_H_
+
+#include <queue>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "remoting/client/gl_cursor.h"
+#include "remoting/client/gl_cursor_feedback.h"
+#include "remoting/client/gl_desktop.h"
+#include "remoting/proto/control.pb.h"
+
+namespace webrtc {
+class DesktopFrame;
+}  // namespace webrtc
+
+namespace remoting {
+
+namespace protocol {
+class CursorShapeInfo;
+}  // namespace protocol
+
+class GlCanvas;
+
+// Renders desktop and cursor on the OpenGL surface. Can be created on any
+// thread but thereafter must be used and deleted on the same thread (usually
+// the display thread. Or any Chromium thread with a task runner attached to
+// it) unless otherwise noted.
+// The unit of all length arguments is pixel.
+class GlRenderer {
+ public:
+  // void RenderCallback(const base::Closure& draw_closure)

[Sergey Ulanov, 2016/07/25 19:34:14]

this line looks like commented method declaration. Do you need it?

[Yuwei, 2016/07/25 19:52:18]

Just try to show how the header of the callback will look like. Maybe it's
unnecessary...

+  //
+  // The callback should do preparation before and after rendering and call
+  // |draw_closure| to draw everything on current OpenGL buffer. You don't need
+  // to run |draw_closure| if it can't be done when running the RenderCallback.
+  // For example:
+  //
+  //   if (!egl_context_established_) {
+  //    return;
+  //   }
+  //   draw_closure.Run();
+  //   SwapBuffers();
+  //   ui_task_runner_->PostTask(FROM_HERE, render_done_);

[Sergey Ulanov, 2016/07/25 19:34:13]

What is render_done_ and how is it relevant here?

[Yuwei, 2016/07/25 19:52:18]

Just an example of how the caller may implement this callback... The caller may
want to notify the UI thread to continue processing animation after the frame is
rendered.

+  //
+  // |draw_closure| must be run on the display thread.
+  using RenderCallback = base::Callback<void(const base::Closure&)>;

[Sergey Ulanov, 2016/07/25 19:34:13]

So if I understand correctly the handler is responsible for deciding if the
frame should be rendered or not. Is that correct understanding?
Would it make code simpler if you replace this with a delegate interface that
tells the renderer if we can render or not.

 class Delegate() {
   virtual bool CanRenderFrame() = 0;
   virtual void OnFrameRendered() = 0;
   virtual void OnSizeChanged(int width, int height) = 0;
 }

You can also use the same delegate to replace SizeCallback, which would help to
avoid 2 Set*Callback() methods. 

[Sergey Ulanov, 2016/07/25 19:34:13]

add name of the argument for the callback, e.g.
base::Callback<void(const base::Closure& done_callback)>

[Yuwei, 2016/07/26 05:01:43]

Obsolete.

[Yuwei, 2016/07/26 05:01:44]

Done.

+
+  // void SizeCallback(int width, int height)

[Sergey Ulanov, 2016/07/25 19:34:13]

remove this line?

[Yuwei, 2016/07/26 05:01:44]

Obsolete.

+  using SizeCallback = base::Callback<void(int, int)>;

[Sergey Ulanov, 2016/07/25 19:34:13]

 base::Callback<void(int width, int height)>

[Yuwei, 2016/07/26 05:01:43]

Obsolete.

+
+  explicit GlRenderer();
+  ~GlRenderer();
+
+  // The render callback can be set on any thread no more than once before
+  // calling any On* functions.
+  //|callback| will be run on the display thread whenever the canvas need to be
+  // redrawn.
+  void SetRenderCallback(const RenderCallback& callback);
+
+  // Sets the callback to be called when the size of the canvas (desktop frame)
+  // is changed. The callback can be set on any thread no more than once before
+  // calling any On* functions.
+  // |callback| will be run on the display thread.
+  void SetCanvasSizeChangedCallback(const SizeCallback& callback);
+
+  // Calls |canvas_size_changed_callback_| with the current canvas size. Canvas
+  // size will be (0, 0) if no desktop frame is received yet.
+  // Caller can use this function to get the canvas size when the surface is
+  // recreated.
+  void RequestCanvasSize();
+
+  // Sets the pixel based transformation matrix related to the size of the
+  // canvas.
+  // 3 by 3 transformation matrix, [ m0, m1, m2, m3, m4, m5, m6, m7, m8 ].
+  //
+  // | m0, m1, m2, |   | x |
+  // | m3, m4, m5, | * | y |
+  // | m6, m7, m8  |   | 1 |
+  //
+  // The final size of the canvas will be (m0*canvas_width, m4*canvas_height)
+  // and the top-left corner will be (m2, m5) in pixel coordinates.
+  void OnPixelTransformationChanged(std::unique_ptr<std::array<float, 9>> mat);
+
+  void OnCursorMoved(int x, int y);
+
+  void OnCursorInputFeedback(int x, int y, float diameter);
+
+  void OnCursorVisibilityChanged(bool visible);
+
+  // Called when a desktop frame is received.
+  // The size of the canvas is determined by the dimension of the desktop frame.
+  // |done| will be queued up and called on the display thread after the actual
+  // rendering happens.
+  void OnFrameReceived(std::unique_ptr<webrtc::DesktopFrame> frame,
+                       const base::Closure& done);
+
+  void OnCursorShapeChanged(const protocol::CursorShapeInfo& shape);
+
+  // Called after the EGL/EAGL context is established and the surface is created
+  // (or recreated). Previous desktop frame and canvas transformation will be
+  // lost after calling this function.
+  // Caller must call OnSurfaceDestroyed() before calling this function if the
+  // surface is recreated.
+  void OnSurfaceCreated(int gl_version);
+
+  // Sets the size of the view. Called right after OnSurfaceCreated() or
+  // whenever the view size is changed.
+  void OnSurfaceChanged(int view_width, int view_height);
+
+  // Called when the surface is destroyed.
+  void OnSurfaceDestroyed();
+
+  // Returns the weak pointer to be used on the display thread.
+  base::WeakPtr<GlRenderer> GetWeakPtr();
+
+ private:
+  // Post a rendering task to the task runner of current thread.
+  // Do nothing if render_callback_ is not set yet or an existing rendering task
+  // in the queue will cover changes before this function is called.
+  void RequestRender();
+
+  // Turns off the |render_scheduled_| flag and runs |render_callback_|.
+  void OnRender();
+
+  // Draws out everything on current OpenGL buffer and runs closures in
+  // |pending_done_callbacks_|.
+  void OnDrawFrame();
+
+  RenderCallback render_callback_;
+
+  SizeCallback canvas_size_changed_callback_;
+
+  // Done callbacks from OnFrameReceived. Will all be called once rendering
+  // takes place.
+  std::queue<base::Closure> pending_done_callbacks_;
+
+  bool render_scheduled_ = false;
+
+  int view_width_ = 0;
+  int view_height_ = 0;
+  int canvas_width_ = 0;
+  int canvas_height_ = 0;
+
+  std::unique_ptr<GlCanvas> canvas_;
+
+  GlCursor cursor_;
+  GlCursorFeedback cursor_feedback_;
+  GlDesktop desktop_;
+
+  base::ThreadChecker thread_checker_;
+  base::WeakPtr<GlRenderer> weak_ptr_;
+  base::WeakPtrFactory<GlRenderer> weak_factory_;
+  DISALLOW_COPY_AND_ASSIGN(GlRenderer);

[Sergey Ulanov, 2016/07/25 19:34:13]

nit: empty line here

[Yuwei, 2016/07/26 05:01:44]

Done.

+};
+
+}  // namespace remoting
+#endif  // REMOTING_CLIENT_GL_RENDERER_H_

[Sergey Ulanov, 2016/07/25 19:34:13]

nit: empty line here

[Yuwei, 2016/07/26 05:01:44]

Done.