[Remoting] OpenGL Rendering Layer

remoting/client/gl_render_layer.h

Index: remoting/client/gl_render_layer.h
diff --git a/remoting/client/gl_render_layer.h b/remoting/client/gl_render_layer.h
new file mode 100644
index 0000000000000000000000000000000000000000..785961f0fa6fdf6004d6be9d51e1a498f74ff3d6
--- /dev/null
+++ b/remoting/client/gl_render_layer.h
@@ -0,0 +1,75 @@
+// 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_OPENGL_GL_RENDER_LAYER_H_
+#define REMOTING_CLIENT_OPENGL_GL_RENDER_LAYER_H_
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "remoting/client/sys_opengl.h"
+
+namespace remoting {
+class GlCanvas;
+
+// This class is for drawing a texture on the canvas. Must be deleted before the
+// canvas is deleted.
+class GlRenderLayer {
+ public:
+  // texture_id: An integer in range [0, GL_MAX_TEXTURE_IMAGE_UNITS], defining
+  //             which slot to store the texture.
+  GlRenderLayer(int texture_id, GlCanvas* canvas);
+  ~GlRenderLayer();
+
+  // Sets the texture (RGBA 8888) to be drawn. Please use UpdateTexture() if the
+  // texture size isn't changed.
+  void SetTexture(const uint8_t* texture, int width, int height);
+
+  // Updates a subregion (RGBA 8888) of the texture.
+  // stride: byte distance between two rows in |subtexture|.
+  // If |stride| is 0 or |stride| == |width|*kBytesPerPixel, |subtexture| will
+  // be treated as tightly packed.
+  void UpdateTexture(const uint8_t* subtexture,
+                     int offset_x,
+                     int offset_y,
+                     int width,
+                     int height,
+                     int stride);
+
+  // Sets the positions of four vertices of the texture in normalized
+  // coordinates. The default values are (0, 0), (0, 1), (1, 0), (1, 1),
+  // i.e. stretching the texture to fit the whole canvas.
+  // positions: [ x_upperleft, y_upperleft, x_lowerleft, y_lowerleft,
+  //              x_upperright, y_upperright, x_lowerright, y_lowerright ]
+  void SetVertexPositions(const std::array<float, 8>& positions);
+
+  // Sets the visible area of the texture. The default values are (0, 0),
+  // (0, 1), (1, 0), (1, 1), i.e. showing the whole texture.
+  // positions: [ x_upperleft, y_upperleft, x_lowerleft, y_lowerleft,
+  //              x_upperright, y_upperright, x_lowerright, y_lowerright ]
+  void SetTextureVisibleArea(const std::array<float, 8>& positions);
+
+  // Draws the texture on the canvas. Texture must be set before calling Draw().
+  void Draw();
+
+ private:
+  int texture_id_;
+  GlCanvas* canvas_;
+
+  GLuint texture_handle_;
+  GLuint buffer_handle_;
+
+  // true IFF the texture is already set by calling SetTexture().
+  bool texture_set_ = false;
+
+  // Used in OpenGL ES 2 context which doesn't support GL_UNPACK_ROW_LENGTH to
+  // tightly pack dirty regions before sending them to GPU.
+  std::unique_ptr<uint8_t[]> update_buffer_;
+  int update_buffer_size_ = 0;
+
+  base::ThreadChecker thread_checker_;
+  DISALLOW_COPY_AND_ASSIGN(GlRenderLayer);
+};
+
+}  // namespace remoting
+#endif  // REMOTING_CLIENT_OPENGL_GL_RENDER_LAYER_H_