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;
+
+    // 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 mImageFrame;
+
+    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 mImageFrame. Note here we fix the
+     *  height of the desktop and vary width accordingly.
+     */
+    public void updateFrameData() {
+        float newHalfDesktopWidth = mImageFrame.getWidth() * HALF_HEIGHT / mImageFrame.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
+            });
+        }
+
+        TextureHelper.linkTexture(mTextureDataHandle, mImageFrame);
+    }
+
+    /**
+     * 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 image frame data are already loaded in.
+     */
+    public boolean hasImageFrame() {
+        return mImageFrame != null;
+    }
+
+    public float getHalfHeight() {
+        return HALF_HEIGHT;
+    }
+
+    public float getHalfWidth() {
+        return mHalfWidth;
+    }
+
+    public void setImageFrame(Bitmap imageFrame) {

[Lambros, 2015/08/20 20:40:56]

Combine this with updateFrameData() - no need for these to be separate methods.
Also, in JniInterface, we call it "Video Frame" and "Frame Bitmap".
So maybe call the method updateVideoFrame() or updateFrameBitmap(), and pass in
the Bitmap as a parameter.

[shichengfeng, 2015/08/20 21:29:37]

Done.

+        mImageFrame = imageFrame;
+    }
+
+    public int getHeightPixels() {
+        return mImageFrame.getHeight();

[Lambros, 2015/08/20 20:40:56]

mImageFrame == null ? 0 : mImageFrame.getHeight()

Or:
Document that this should only be called when hasImageFrame() returns true, and
fix the calling code to check this.

[shichengfeng, 2015/08/20 21:29:37]

Done.

+    }
+
+    public int getWidthPixels() {
+        return mImageFrame.getWidth();

[Lambros, 2015/08/20 20:40:56]

same here

[shichengfeng, 2015/08/20 21:29:37]

Done.

+    }
+}