Adding drawable to CRD andorid and iOS gl rendering pipeline.

remoting/client/gl_canvas.h

Index: remoting/client/gl_canvas.h
diff --git a/remoting/client/gl_canvas.h b/remoting/client/gl_canvas.h
index 4df0a4b8d6bcb2dbccc9fc03744975eb48331bc7..36b30f4fbf17b120596df1f67d19bd7e2ba61e48 100644
--- a/remoting/client/gl_canvas.h
+++ b/remoting/client/gl_canvas.h
@@ -22,7 +22,7 @@ class GlCanvas {
   // gl_version: version number of the OpenGL ES context. Either 2 or 3.
   GlCanvas(int gl_version);
 
-  ~GlCanvas();
+  virtual ~GlCanvas();
 
   // Sets the transformation matrix. This matrix defines how the canvas should
   // be shown on the view.
@@ -42,6 +42,9 @@ class GlCanvas {
   // Sets the size of the view in pixels.
   void SetViewSize(int width, int height);
 
+  // Clears the frame.
+  virtual void Clear();
+
   // Draws the texture on the canvas. Nothing will happen if
   // SetNormalizedTransformation() has not been called.
   // vertex_buffer: reference to the 2x4x2 float vertex buffer.
@@ -64,7 +67,11 @@ class GlCanvas {
   // the height of the texture can exceed this limitation.
   int GetMaxTextureSize() const;
 
+  static GlCanvas* CreateGlCanvas(int gl_version);

[joedow, 2016/12/22 19:18:09]

If you want the caller to own the instance, the expected ownership would be more
transparent if you returned a std::unique_ptr here instead.  It will also
prevent leaks.

[nicholss, 2017/01/09 18:50:24]

good call. Changing to return a std::unique_prt.

+
  private:
+  friend class FakeGlCanvas;
+  GlCanvas();
   int gl_version_;
 
   int max_texture_size_ = 0;
@@ -84,11 +91,36 @@ class GlCanvas {
   GLuint position_location_;
   GLuint tex_cord_location_;
 
+  bool gl_constructed_;

[joedow, 2016/12/22 00:29:02]

You should use inline inits for primitives instead of using initializer lists
(or leaving it uninitialized :P)

[nicholss, 2017/01/09 18:50:24]

this was removed and replaced with the use of an interface and a fake impl.

+
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(GlCanvas);
 };
 
+class FakeGlCanvas : public GlCanvas {

[Yuwei, 2016/12/21 23:41:59]

Is this just for testing? I think it will be clearer if you make this into an
individual file and make a common interface for both the fake one and the real
one.

Also you may still be able to verify the drawing order without introducing a
fake canvas. Currently if the canvas is null, no drawable will attempt to draw.

[joedow, 2016/12/22 00:29:02]

This should go into a separate file, most of the fakes live in remoting/test. 
That way this code isn't included in production code, only the test_support
target.

Also, no impls in the header.

[nicholss, 2016/12/22 16:21:41]

This was added to support testing that the draw methods get called. 

I was not sure if it was worth it to make a new interface, so I tried this
method with CreateGlCanvas. Thoughts?

[Yuwei, 2016/12/22 19:01:10]

We do sometimes use interface to make things testable. See X11Keyboard and
X11KeyboarImpl.

I think it is more important to make sure the implementation code is isolated
from the test code so that later if we want to test against the real OpenGL
context, we can easily remove the interface/test code without needing to do
nontrivial changes to the implementation.

[joedow, 2016/12/22 19:18:09]

We separate prod and test code routinely.  If you need an interface, you can do
that, otherwise the fake instance can inherit from the production class (as it
is doing here) and stub out the methods it cares about.

[nicholss, 2017/01/09 18:50:24]

Went ahead and created the interface.

+ public:
+  FakeGlCanvas() {}
+
+  ~FakeGlCanvas() override {}
+  void SetTransformationMatrix(const std::array<float, 9>& matrix) {}
+
+  void SetViewSize(int width, int height) {}
+
+  void Clear() override {}
+
+  void DrawTexture(int texture_id,
+                   GLuint texture_handle,
+                   GLuint vertex_buffer,
+                   float alpha_multiplier) {}
+
+  int GetGlVersion() const { return -1; }
+
+  int GetMaxTextureSize() const { return 0; }
+
+  DISALLOW_COPY_AND_ASSIGN(FakeGlCanvas);
+};
+
 }  // namespace remoting
 
 #endif  // REMOTING_CLIENT_OPENGL_GL_CANVAS_H_