Adding the iOS app and integration example with GlRenderer.

remoting/client/ios/display/gl_demo_screen.mm

Index: remoting/client/ios/display/gl_demo_screen.mm
diff --git a/remoting/client/ios/display/gl_demo_screen.mm b/remoting/client/ios/display/gl_demo_screen.mm
new file mode 100644
index 0000000000000000000000000000000000000000..db549817b73e4d2bb5170b8094fabd112af36733
--- /dev/null
+++ b/remoting/client/ios/display/gl_demo_screen.mm
@@ -0,0 +1,115 @@
+// Copyright 2017 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"
+
+#include "base/logging.h"
+#include "remoting/client/display/canvas.h"
+#include "remoting/client/display/gl_math.h"
+
+namespace remoting {
+
+namespace {
+
+const GLfloat square[] = {-1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0};

[Sergey Ulanov, 2017/01/27 19:47:44]

This should be kSquare (or kSquareCoordinates).
Same for the consts below.

See 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";

[Sergey Ulanov, 2017/01/27 19:47:44]

kPositionAttributeName

+
+}  // namespace
+
+// This is a demo screen that can be added to the renderer to test the drawable
+// integration. This will draw an expanding checkerboard pattern to the screen.
+GlDemoScreen::GlDemoScreen() : weak_factory_(this)  {}
+
+GlDemoScreen::~GlDemoScreen() {}
+
+void GlDemoScreen::SetCanvas(base::WeakPtr<Canvas> 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_);
+}
+
+int GlDemoScreen::GetZIndex() {
+  return Drawable::DESKTOP + 1;
+}
+
+bool GlDemoScreen::Draw() {
+  if (!canvas_) {
+    return false;
+  }
+
+  // TODO(nicholss): width and height should be dynamic based on the canvas.
+  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_);
+
+  int skip = 0;
+  for (int i = 0; i < width; i += square_size_) {
+    if (skip == square_size_) {

[Sergey Ulanov, 2017/01/27 19:47:44]

This whole statement can be written as follows.
 skip = (i % 2) * square_size_;

and then skip can be moved inside the loop.

+      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);
+
+      glVertexAttribPointer(aPosition, 2, GL_FLOAT, GL_FALSE, 0, square);
+      glEnableVertexAttribArray(aPosition);
+
+      // Draw.
+      glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+  }
+  return true;
+}
+
+base::WeakPtr<Drawable> GlDemoScreen::GetWeakPtr() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return weak_factory_.GetWeakPtr();
+}
+
+}  // namespace remoting