Refactor drawing desktop.

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

+// 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.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;
+
+    // Size of the vertexes to draw desktop.

[Lambros, 2015/08/19 23:17:28]

English grammar: You can say "number of items in a list" or you can say "size of
a list". But not "size of items" because that's talking about the size of each
item individually.

I would simply say "Number of vertices passed to glDrawArrays()."
or "Size of vertex list passed to glDrawArrays()."

without talking about "desktop" or "eye position" or anything else. You can then
copy-paste the same comment in every similar refactoring.

[shichengfeng, 2015/08/20 01:02:53]

Done.

+    private static final int VERTEXES_NUMBER = 6;

[Lambros, 2015/08/19 23:17:28]

s/VERTEXES/VERTICES/

Code-search has only 4 hits for "vertexes" and 803 hits for "vertices" :)

[shichengfeng, 2015/08/20 01:02:53]

Done.

+
+    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;
+
+    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();
+    }
+
+    public void setTexture(Bitmap texture) {
+        TextureHelper.linkTexture(mTextureDataHandle, texture);
+    }
+
+    public void setPosition(FloatBuffer position) {

[Lambros, 2015/08/19 23:17:28]

You won't need this if you move the FloatBuffer into this class.

[shichengfeng, 2015/08/20 01:02:53]

Done.

+        mPosition = position;
+    }
+
+    public void setCombinedMatrix(float[] combinedMatrix) {
+        mCombinedMatrix = combinedMatrix.clone();
+    }
+
+    /**
+     * 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, VERTEXES_NUMBER);
+    }
+
+    /**
+     * Clean up opengl data.
+     */
+    public void cleanup() {
+        GLES20.glDeleteShader(mVertexShaderHandle);
+        GLES20.glDeleteShader(mFragmentShaderHandle);
+        GLES20.glDeleteTextures(1, new int[] {mTextureDataHandle}, 0);
+    }
+}