Refactor drawing desktop.

remoting/android/java/src/org/chromium/chromoting/CardboardActivityDesktop.java

Index: remoting/android/java/src/org/chromium/chromoting/CardboardActivityDesktop.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/CardboardActivityDesktop.java b/remoting/android/java/src/org/chromium/chromoting/CardboardActivityDesktop.java
new file mode 100644
index 0000000000000000000000000000000000000000..cc149b099eb36876370423fa5aa6bdd5532ab2e3
--- /dev/null
+++ b/remoting/android/java/src/org/chromium/chromoting/CardboardActivityDesktop.java
@@ -0,0 +1,180 @@
+// Copyright 2015 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.
+
+package org.chromium.chromoting;
+
+import static org.chromium.chromoting.CardboardDesktopRenderer.makeFloatBuffer;
+
+import android.graphics.Bitmap;
+import android.graphics.Point;
+import android.opengl.GLES20;
+
+import java.nio.FloatBuffer;
+
+/**
+ * Chromoting Cardboard activity desktop, which is used to display host desktop.
+ */
+public class CardboardActivityDesktop {
+    private static final String VERTEX_SHADER =
+            "uniform mat4 u_CombinedMatrix;"
+            + "attribute vec4 a_Position;"
+            + "attribute vec2 a_TexCoordinate;"
+            + "varying vec2 v_TexCoordinate;"
+            + "void main() {"
+            + "  v_TexCoordinate = a_TexCoordinate;"
+            + "  gl_Position = u_CombinedMatrix * a_Position;"
+            + "}";
+
+    private static final String FRAGMENT_SHADER =
+            "precision mediump float;"
+            + "uniform sampler2D u_Texture;"
+            + "varying vec2 v_TexCoordinate;"
+            + "void main() {"
+            + "  gl_FragColor = texture2D(u_Texture, v_TexCoordinate);"
+            + "}";
+
+    private static final FloatBuffer TEXTURE_COORDINATES = makeFloatBuffer(new float[] {
+            // Texture coordinate data.
+            0.0f, 0.0f,
+            0.0f, 1.0f,
+            1.0f, 0.0f,
+            0.0f, 1.0f,
+            1.0f, 1.0f,
+            1.0f, 0.0f
+    });
+
+    private static final int POSITION_DATA_SIZE = 3;
+    private static final int TEXTURE_COORDINATE_DATA_SIZE = 2;
+
+    // Fix the desktop height and adjust width accordingly.
+    private static final float HALF_HEIGHT = 1.0f;
+
+    // Number of vertices passed to glDrawArrays().
+    private static final int VERTICES_NUMBER = 6;
+
+    private int mVertexShaderHandle;
+    private int mFragmentShaderHandle;
+    private int mProgramHandle;
+    private int mCombinedMatrixHandle;
+    private int mTextureUniformHandle;
+    private int mPositionHandle;
+    private int mTextureDataHandle;
+    private int mTextureCoordinateHandle;
+    private FloatBuffer mPosition;
+    private float[] mCombinedMatrix;
+    private float mHalfWidth;
+    private Bitmap mVideoFrame;
+
+    // Lock to allow multithreaded access to mVideoFrame.
+    private Object mVideoFrameLock = new Object();
+
+    public CardboardActivityDesktop() {
+        mVertexShaderHandle =
+                ShaderHelper.compileShader(GLES20.GL_VERTEX_SHADER, VERTEX_SHADER);
+        mFragmentShaderHandle =
+                ShaderHelper.compileShader(GLES20.GL_FRAGMENT_SHADER, FRAGMENT_SHADER);
+        mProgramHandle = ShaderHelper.createAndLinkProgram(mVertexShaderHandle,
+                mFragmentShaderHandle, new String[] {"a_Position", "a_TexCoordinate",
+                    "u_CombinedMatrix", "u_Texture"});
+        mCombinedMatrixHandle =
+                GLES20.glGetUniformLocation(mProgramHandle, "u_CombinedMatrix");
+        mTextureUniformHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_Texture");
+        mPositionHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_Position");
+        mTextureCoordinateHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_TexCoordinate");
+        mTextureDataHandle = TextureHelper.createTextureHandle();
+    }
+
+    /**
+     * Draw the desktop. Make sure texture, position, and model view projection matrix
+     * are passed in before calling this method.
+     */
+    public void draw() {
+        GLES20.glUseProgram(mProgramHandle);
+
+        // Pass in model view project matrix.
+        GLES20.glUniformMatrix4fv(mCombinedMatrixHandle, 1, false, mCombinedMatrix, 0);
+
+        // Pass in texture coordinate.
+        GLES20.glVertexAttribPointer(mTextureCoordinateHandle, TEXTURE_COORDINATE_DATA_SIZE,
+                GLES20.GL_FLOAT, false, 0, TEXTURE_COORDINATES);
+        GLES20.glEnableVertexAttribArray(mTextureCoordinateHandle);
+
+        GLES20.glVertexAttribPointer(mPositionHandle, POSITION_DATA_SIZE, GLES20.GL_FLOAT, false,
+                0, mPosition);
+        GLES20.glEnableVertexAttribArray(mPositionHandle);
+
+        // Link texture data with texture unit.
+        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
+        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureDataHandle);
+        GLES20.glUniform1i(mTextureUniformHandle, 0);
+
+        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, VERTICES_NUMBER);
+    }
+
+    /**
+     *  Update the desktop frame data based on the mVideoFrame. Note here we fix the
+     *  height of the desktop and vary width accordingly.
+     */
+    public void updateVideoFrameData(Bitmap videoFrame) {

[Lambros, 2015/08/21 00:08:39]

You chose hasVideoFrame() instead of hasVideoFrameData(), so maybe shorten this
to updateVideoFrame() ?

[shichengfeng, 2015/08/21 00:42:53]

Done.

+        float newHalfDesktopWidth;
+        synchronized (mVideoFrameLock) {
+            mVideoFrame = videoFrame;
+            TextureHelper.linkTexture(mTextureDataHandle, videoFrame);
+            newHalfDesktopWidth = videoFrame.getWidth() * HALF_HEIGHT / videoFrame.getHeight();
+        }
+
+        if (Math.abs(mHalfWidth - newHalfDesktopWidth) > 0.0001) {
+            mHalfWidth = newHalfDesktopWidth;
+            mPosition = makeFloatBuffer(new float[] {
+                    // Desktop model coordinates.
+                    -mHalfWidth, HALF_HEIGHT, 0.0f,
+                    -mHalfWidth, -HALF_HEIGHT, 0.0f,
+                    mHalfWidth, HALF_HEIGHT, 0.0f,
+                    -mHalfWidth, -HALF_HEIGHT, 0.0f,
+                    mHalfWidth, -HALF_HEIGHT, 0.0f,
+                    mHalfWidth, HALF_HEIGHT, 0.0f
+            });
+        }
+    }
+
+    /**
+     * Clean up opengl data.
+     */
+    public void cleanup() {
+        GLES20.glDeleteShader(mVertexShaderHandle);
+        GLES20.glDeleteShader(mFragmentShaderHandle);
+        GLES20.glDeleteTextures(1, new int[] {mTextureDataHandle}, 0);
+    }
+
+    public void setCombinedMatrix(float[] combinedMatrix) {
+        mCombinedMatrix = combinedMatrix.clone();
+    }
+
+    /**
+     * Return true if video frame data are already loaded in.
+     */
+    public boolean hasVideoFrame() {
+        synchronized (mVideoFrameLock) {
+            return mVideoFrame != null;
+        }
+    }
+
+    public float getHalfHeight() {
+        return HALF_HEIGHT;
+    }
+
+    public float getHalfWidth() {
+        return mHalfWidth;

[Lambros, 2015/08/21 00:08:39]

Is this called on the UI thread? If so, you need to synchronize on
mVideoFrameLock, because mHalfWidth is set on the OpenGL thread in
updateVideoFrameData().

[shichengfeng, 2015/08/21 00:42:53]

Done.

+    }
+
+    /**
+     * Get desktop height and width pixels.

[Lambros, 2015/08/21 00:08:39]

s/pixels/in pixels/

[shichengfeng, 2015/08/21 00:42:53]

Done.

+     */
+    public Point getShapePixels() {

[Lambros, 2015/08/21 00:08:39]

"shape" is unclear, I think.
Maybe getFrameSizePixels() or getVideoFrameSize() ?

[shichengfeng, 2015/08/21 00:42:53]

Done.

+        synchronized (mVideoFrameLock) {
+            return new Point(mVideoFrame == null ? 0 : mVideoFrame.getHeight(),
+                    mVideoFrame == null ? 0 : mVideoFrame.getWidth());
+        }
+    }
+}