Adding the iOS app and integration example with GlRenderer.

remoting/client/ios/display/gl_demo_screen.mm

+// 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 "remoting/client/ios/display/gl_demo_screen.h"
+
+#import <Foundation/Foundation.h>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "remoting/client/gl_canvas.h"
+#include "remoting/client/gl_math.h"
+
+namespace remoting {
+
+const GLfloat square[] = {-1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0};

[Yuwei, 2016/12/19 23:26:09]

kSquare?

https://google.github.io/styleguide/cppguide.html#Constant_Names

+
+const GLchar* fragmentShaderSource =
+    "precision mediump float;"
+    "void main() {"
+    "  gl_FragColor = vec4(1.0, 1.0, 0.0, 1.0);"
+    "} ";
+
+const GLchar* vertexShaderSource =
+    "precision mediump float;"
+    "attribute vec4 a_position;"
+    "void main() {"
+    "  gl_Position = a_position;"
+    "}";
+
+const GLchar* a_position = "a_position";

[Yuwei, 2016/12/19 23:26:09]

Maybe |kAPositionAttribute|?

+
+GlDemoScreen::GlDemoScreen() {}
+
+GlDemoScreen::~GlDemoScreen() {}
+
+void GlDemoScreen::SetCanvas(GlCanvas* canvas) {
+  canvas_ = canvas;
+
+  // Create and compile vertex shader
+  GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+  glCompileShader(vertexShader);
+
+  // Create and compile fragment shader
+  GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+  glCompileShader(fragmentShader);
+
+  // Create and link program
+  program = glCreateProgram();
+  glAttachShader(program, vertexShader);
+  glAttachShader(program, fragmentShader);
+  glLinkProgram(program);
+}
+
+void GlDemoScreen::Draw() {
+  if (!canvas_) {
+    return;
+  }
+
+  int width = 640;
+  int height = 1024;
+  square_size++;
+  if (square_size > 300) {
+    square_size = 1;
+  }
+
+  // Set the viewport
+  glViewport(0, 0, width, height);
+
+  // Clear
+  glClearColor(0, 1, 0, 1);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  // Use program
+  glUseProgram(program);

[Yuwei, 2016/12/19 23:26:09]

GlCanvas was supposed to be used to draw textures on the view. If you want to
use your own program to draw the demo then I think you should also move the
glUseProgram() call from GlCanvas' contrustor to the beginning of
GlCanvas::DrawTexture.

+
+  int skip = 0;
+  for (int i = 0; i < width; i += square_size) {
+    if (skip == square_size) {
+      skip = 0;
+    } else {
+      skip = square_size;
+    }
+    for (int j = skip; j < height; j += square_size * 2) {
+      glViewport(i, j, square_size, square_size);
+
+      // Send geometry to vertex shader
+      GLuint aPosition = glGetAttribLocation(program, a_position);

[Yuwei, 2016/12/19 23:26:09]

Nit: maybe getting it once and store it in SetCanvas? The position should not
change after the program is created.

s/aPosition/a_position/?

+
+      glVertexAttribPointer(aPosition, 2, GL_FLOAT, GL_FALSE, 0, square);
+      glEnableVertexAttribArray(aPosition);
+
+      // Draw
+      glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+  }
+}
+
+}  // namespace remoting