content: /*
   * Copyright (C) 2012 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.android.gallery3d.glrenderer;
  
  import android.graphics.Bitmap;
  import android.graphics.Rect;
  import android.graphics.RectF;
  import android.opengl.GLES20;
  import android.opengl.GLUtils;
  import android.opengl.Matrix;
  import android.util.Log;
  
  import com.android.gallery3d.util.IntArray;
  
  import java.nio.Buffer;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.FloatBuffer;
  import java.util.ArrayList;
  import java.util.Arrays;
  
  public class GLES20Canvas implements GLCanvas {
      // ************** Constants **********************
      private static final String TAG = GLES20Canvas.class.getSimpleName();
      private static final int FLOAT_SIZE = Float.SIZE / Byte.SIZE;
      private static final float OPAQUE_ALPHA = 0.95f;
  
      private static final int COORDS_PER_VERTEX = 2;
      private static final int VERTEX_STRIDE = COORDS_PER_VERTEX * FLOAT_SIZE;
  
      private static final int COUNT_FILL_VERTEX = 4;
      private static final int COUNT_LINE_VERTEX = 2;
      private static final int COUNT_RECT_VERTEX = 4;
      private static final int OFFSET_FILL_RECT = 0;
      private static final int OFFSET_DRAW_LINE = OFFSET_FILL_RECT + COUNT_FILL_VERTEX;
      private static final int OFFSET_DRAW_RECT = OFFSET_DRAW_LINE + COUNT_LINE_VERTEX;
  
      private static final float[] BOX_COORDINATES = {
              0, 0, // Fill rectangle
              1, 0,
              0, 1,
              1, 1,
              0, 0, // Draw line
              1, 1,
              0, 0, // Draw rectangle outline
              0, 1,
              1, 1,
              1, 0,
      };
  
      private static final float[] BOUNDS_COORDINATES = {
          0, 0, 0, 1,
          1, 1, 0, 1,
      };
  
      private static final String POSITION_ATTRIBUTE = "aPosition";
      private static final String COLOR_UNIFORM = "uColor";
      private static final String MATRIX_UNIFORM = "uMatrix";
      private static final String TEXTURE_MATRIX_UNIFORM = "uTextureMatrix";
      private static final String TEXTURE_SAMPLER_UNIFORM = "uTextureSampler";
      private static final String ALPHA_UNIFORM = "uAlpha";
      private static final String TEXTURE_COORD_ATTRIBUTE = "aTextureCoordinate";
  
      private static final String DRAW_VERTEX_SHADER = ""
              + "uniform mat4 " + MATRIX_UNIFORM + ";\n"
              + "attribute vec2 " + POSITION_ATTRIBUTE + ";\n"
              + "void main() {\n"
              + "  vec4 pos = vec4(" + POSITION_ATTRIBUTE + ", 0.0, 1.0);\n"
              + "  gl_Position = " + MATRIX_UNIFORM + " * pos;\n"
              + "}\n";
  
      private static final String DRAW_FRAGMENT_SHADER = ""
              + "precision mediump float;\n"
              + "uniform vec4 " + COLOR_UNIFORM + ";\n"
              + "void main() {\n"
              + "  gl_FragColor = " + COLOR_UNIFORM + ";\n"
              + "}\n";
  
      private static final String TEXTURE_VERTEX_SHADER = ""
              + "uniform mat4 " + MATRIX_UNIFORM + ";\n"
              + "uniform mat4 " + TEXTURE_MATRIX_UNIFORM + ";\n"
              + "attribute vec2 " + POSITION_ATTRIBUTE + ";\n"
              + "varying vec2 vTextureCoord;\n"
              + "void main() {\n"
              + "  vec4 pos = vec4(" + POSITION_ATTRIBUTE + ", 0.0, 1.0);\n"
              + "  gl_Position = " + MATRIX_UNIFORM + " * pos;\n"
              + "  vTextureCoord = (" + TEXTURE_MATRIX_UNIFORM + " * pos).xy;\n"
              + "}\n";
  
      private static final String MESH_VERTEX_SHADER = ""
              + "uniform mat4 " + MATRIX_UNIFORM + ";\n"
              + "attribute vec2 " + POSITION_ATTRIBUTE + ";\n"
              + "attribute vec2 " + TEXTURE_COORD_ATTRIBUTE + ";\n"
              + "varying vec2 vTextureCoord;\n"
              + "void main() {\n"
              + "  vec4 pos = vec4(" + POSITION_ATTRIBUTE + ", 0.0, 1.0);\n"
              + "  gl_Position = " + MATRIX_UNIFORM + " * pos;\n"
              + "  vTextureCoord = " + TEXTURE_COORD_ATTRIBUTE + ";\n"
              + "}\n";
  
      private static final String TEXTURE_FRAGMENT_SHADER = ""
              + "precision mediump float;\n"
              + "varying vec2 vTextureCoord;\n"
              + "uniform float " + ALPHA_UNIFORM + ";\n"
              + "uniform sampler2D " + TEXTURE_SAMPLER_UNIFORM + ";\n"
              + "void main() {\n"
              + "  gl_FragColor = texture2D(" + TEXTURE_SAMPLER_UNIFORM + ", vTextureCoord);\n"
              + "  gl_FragColor *= " + ALPHA_UNIFORM + ";\n"
              + "}\n";
  
      private static final String OES_TEXTURE_FRAGMENT_SHADER = ""
              + "#extension GL_OES_EGL_image_external : require\n"
              + "precision mediump float;\n"
              + "varying vec2 vTextureCoord;\n"
              + "uniform float " + ALPHA_UNIFORM + ";\n"
              + "uniform samplerExternalOES " + TEXTURE_SAMPLER_UNIFORM + ";\n"
              + "void main() {\n"
              + "  gl_FragColor = texture2D(" + TEXTURE_SAMPLER_UNIFORM + ", vTextureCoord);\n"
              + "  gl_FragColor *= " + ALPHA_UNIFORM + ";\n"
              + "}\n";
  
      private static final int INITIAL_RESTORE_STATE_SIZE = 8;
      private static final int MATRIX_SIZE = 16;
  
      // Keep track of restore state
      private float[] mMatrices = new float[INITIAL_RESTORE_STATE_SIZE * MATRIX_SIZE];
      private float[] mAlphas = new float[INITIAL_RESTORE_STATE_SIZE];
      private IntArray mSaveFlags = new IntArray();
  
      private int mCurrentAlphaIndex = 0;
      private int mCurrentMatrixIndex = 0;
  
      // Viewport size
      private int mWidth;
      private int mHeight;
  
      // Projection matrix
      private float[] mProjectionMatrix = new float[MATRIX_SIZE];
  
      // Screen size for when we aren't bound to a texture
      private int mScreenWidth;
      private int mScreenHeight;
  
      // GL programs
      private int mDrawProgram;
      private int mTextureProgram;
      private int mOesTextureProgram;
      private int mMeshProgram;
  
      // GL buffer containing BOX_COORDINATES
      private int mBoxCoordinates;
  
      // Handle indices -- common
      private static final int INDEX_POSITION = 0;
      private static final int INDEX_MATRIX = 1;
  
      // Handle indices -- draw
      private static final int INDEX_COLOR = 2;
  
      // Handle indices -- texture
      private static final int INDEX_TEXTURE_MATRIX = 2;
      private static final int INDEX_TEXTURE_SAMPLER = 3;
      private static final int INDEX_ALPHA = 4;
  
      // Handle indices -- mesh
      private static final int INDEX_TEXTURE_COORD = 2;
  
      private abstract static class ShaderParameter {
          public int handle;
          protected final String mName;
  
          public ShaderParameter(String name) {
              mName = name;
          }
  
          public abstract void loadHandle(int program);
      }
  
      private static class UniformShaderParameter extends ShaderParameter {
          public UniformShaderParameter(String name) {
              super(name);
          }
  
          @Override
          public void loadHandle(int program) {
              handle = GLES20.glGetUniformLocation(program, mName);
              checkError();
          }
      }
  
      private static class AttributeShaderParameter extends ShaderParameter {
          public AttributeShaderParameter(String name) {
              super(name);
          }
  
          @Override
          public void loadHandle(int program) {
              handle = GLES20.glGetAttribLocation(program, mName);
              checkError();
          }
      }
  
      ShaderParameter[] mDrawParameters = {
              new AttributeShaderParameter(POSITION_ATTRIBUTE), // INDEX_POSITION
              new UniformShaderParameter(MATRIX_UNIFORM), // INDEX_MATRIX
              new UniformShaderParameter(COLOR_UNIFORM), // INDEX_COLOR
      };
      ShaderParameter[] mTextureParameters = {
              new AttributeShaderParameter(POSITION_ATTRIBUTE), // INDEX_POSITION
              new UniformShaderParameter(MATRIX_UNIFORM), // INDEX_MATRIX
              new UniformShaderParameter(TEXTURE_MATRIX_UNIFORM), // INDEX_TEXTURE_MATRIX
              new UniformShaderParameter(TEXTURE_SAMPLER_UNIFORM), // INDEX_TEXTURE_SAMPLER
              new UniformShaderParameter(ALPHA_UNIFORM), // INDEX_ALPHA
      };
      ShaderParameter[] mOesTextureParameters = {
              new AttributeShaderParameter(POSITION_ATTRIBUTE), // INDEX_POSITION
              new UniformShaderParameter(MATRIX_UNIFORM), // INDEX_MATRIX
              new UniformShaderParameter(TEXTURE_MATRIX_UNIFORM), // INDEX_TEXTURE_MATRIX
              new UniformShaderParameter(TEXTURE_SAMPLER_UNIFORM), // INDEX_TEXTURE_SAMPLER
              new UniformShaderParameter(ALPHA_UNIFORM), // INDEX_ALPHA
      };
      ShaderParameter[] mMeshParameters = {
              new AttributeShaderParameter(POSITION_ATTRIBUTE), // INDEX_POSITION
              new UniformShaderParameter(MATRIX_UNIFORM), // INDEX_MATRIX
              new AttributeShaderParameter(TEXTURE_COORD_ATTRIBUTE), // INDEX_TEXTURE_COORD
              new UniformShaderParameter(TEXTURE_SAMPLER_UNIFORM), // INDEX_TEXTURE_SAMPLER
              new UniformShaderParameter(ALPHA_UNIFORM), // INDEX_ALPHA
      };
  
      private final IntArray mUnboundTextures = new IntArray();
      private final IntArray mDeleteBuffers = new IntArray();
  
      // Keep track of statistics for debugging
      private int mCountDrawMesh = 0;
      private int mCountTextureRect = 0;
      private int mCountFillRect = 0;
      private int mCountDrawLine = 0;
  
      // Buffer for framebuffer IDs -- we keep track so we can switch the attached
      // texture.
      private int[] mFrameBuffer = new int[1];
  
      // Bound textures.
      private ArrayList<RawTexture> mTargetTextures = new ArrayList<RawTexture>();
  
      // Temporary variables used within calculations
      private final float[] mTempMatrix = new float[32];
      private final float[] mTempColor = new float[4];
      private final RectF mTempSourceRect = new RectF();
      private final RectF mTempTargetRect = new RectF();
      private final float[] mTempTextureMatrix = new float[MATRIX_SIZE];
      private final int[] mTempIntArray = new int[1];
  
      private static final GLId mGLId = new GLES20IdImpl();
  
      public GLES20Canvas() {
          Matrix.setIdentityM(mTempTextureMatrix, 0);
          Matrix.setIdentityM(mMatrices, mCurrentMatrixIndex);
          mAlphas[mCurrentAlphaIndex] = 1f;
          mTargetTextures.add(null);
  
          FloatBuffer boxBuffer = createBuffer(BOX_COORDINATES);
          mBoxCoordinates = uploadBuffer(boxBuffer);
  
          int drawVertexShader = loadShader(GLES20.GL_VERTEX_SHADER, DRAW_VERTEX_SHADER);
          int textureVertexShader = loadShader(GLES20.GL_VERTEX_SHADER, TEXTURE_VERTEX_SHADER);
          int meshVertexShader = loadShader(GLES20.GL_VERTEX_SHADER, MESH_VERTEX_SHADER);
          int drawFragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, DRAW_FRAGMENT_SHADER);
          int textureFragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, TEXTURE_FRAGMENT_SHADER);
          int oesTextureFragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER,
                  OES_TEXTURE_FRAGMENT_SHADER);
  
          mDrawProgram = assembleProgram(drawVertexShader, drawFragmentShader, mDrawParameters);
          mTextureProgram = assembleProgram(textureVertexShader, textureFragmentShader,
                  mTextureParameters);
          mOesTextureProgram = assembleProgram(textureVertexShader, oesTextureFragmentShader,
                  mOesTextureParameters);
          mMeshProgram = assembleProgram(meshVertexShader, textureFragmentShader, mMeshParameters);
          GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA);
          checkError();
      }
  
      private static FloatBuffer createBuffer(float[] values) {
          // First create an nio buffer, then create a VBO from it.
          int size = values.length * FLOAT_SIZE;
          FloatBuffer buffer = ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder())
                  .asFloatBuffer();
          buffer.put(values, 0, values.length).position(0);
          return buffer;
      }
  
      private int assembleProgram(int vertexShader, int fragmentShader, ShaderParameter[] params) {
          int program = GLES20.glCreateProgram();
          checkError();
          if (program == 0) {
              throw new RuntimeException("Cannot create GL program: " + GLES20.glGetError());
          }
          GLES20.glAttachShader(program, vertexShader);
          checkError();
          GLES20.glAttachShader(program, fragmentShader);
          checkError();
          GLES20.glLinkProgram(program);
          checkError();
          int[] mLinkStatus = mTempIntArray;
          GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, mLinkStatus, 0);
          if (mLinkStatus[0] != GLES20.GL_TRUE) {
              Log.e(TAG, "Could not link program: ");
              Log.e(TAG, GLES20.glGetProgramInfoLog(program));
              GLES20.glDeleteProgram(program);
              program = 0;
          }
          for (int i = 0; i < params.length; i++) {
              params[i].loadHandle(program);
          }
          return program;
      }
  
      private static int loadShader(int type, String shaderCode) {
          // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
          // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
          int shader = GLES20.glCreateShader(type);
  
          // add the source code to the shader and compile it
          GLES20.glShaderSource(shader, shaderCode);
          checkError();
          GLES20.glCompileShader(shader);
          checkError();
  
          return shader;
      }
  
      @Override
      public void setSize(int width, int height) {
          mWidth = width;
          mHeight = height;
          GLES20.glViewport(0, 0, mWidth, mHeight);
          checkError();
          Matrix.setIdentityM(mMatrices, mCurrentMatrixIndex);
          Matrix.orthoM(mProjectionMatrix, 0, 0, width, 0, height, -1, 1);
          if (getTargetTexture() == null) {
              mScreenWidth = width;
              mScreenHeight = height;
              Matrix.translateM(mMatrices, mCurrentMatrixIndex, 0, height, 0);
              Matrix.scaleM(mMatrices, mCurrentMatrixIndex, 1, -1, 1);
          }
      }
  
      @Override
      public void clearBuffer() {
          GLES20.glClearColor(0f, 0f, 0f, 1f);
          checkError();
          GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
          checkError();
      }
  
      @Override
      public void clearBuffer(float[] argb) {
          GLES20.glClearColor(argb[1], argb[2], argb[3], argb[0]);
          checkError();
          GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
          checkError();
      }
  
      @Override
      public float getAlpha() {
          return mAlphas[mCurrentAlphaIndex];
      }
  
      @Override
      public void setAlpha(float alpha) {
          mAlphas[mCurrentAlphaIndex] = alpha;
      }
  
      @Override
      public void multiplyAlpha(float alpha) {
          setAlpha(getAlpha() * alpha);
      }
  
      @Override
      public void translate(float x, float y, float z) {
          Matrix.translateM(mMatrices, mCurrentMatrixIndex, x, y, z);
      }
  
      // This is a faster version of translate(x, y, z) because
      // (1) we knows z = 0, (2) we inline the Matrix.translateM call,
      // (3) we unroll the loop
      @Override
      public void translate(float x, float y) {
          int index = mCurrentMatrixIndex;
          float[] m = mMatrices;
          m[index + 12] += m[index + 0] * x + m[index + 4] * y;
          m[index + 13] += m[index + 1] * x + m[index + 5] * y;
          m[index + 14] += m[index + 2] * x + m[index + 6] * y;
          m[index + 15] += m[index + 3] * x + m[index + 7] * y;
      }
  
      @Override
      public void scale(float sx, float sy, float sz) {
          Matrix.scaleM(mMatrices, mCurrentMatrixIndex, sx, sy, sz);
      }
  
      @Override
      public void rotate(float angle, float x, float y, float z) {
          if (angle == 0f) {
              return;
          }
          float[] temp = mTempMatrix;
          Matrix.setRotateM(temp, 0, angle, x, y, z);
          float[] matrix = mMatrices;
          int index = mCurrentMatrixIndex;
          Matrix.multiplyMM(temp, MATRIX_SIZE, matrix, index, temp, 0);
          System.arraycopy(temp, MATRIX_SIZE, matrix, index, MATRIX_SIZE);
      }
  
      @Override
      public void multiplyMatrix(float[] matrix, int offset) {
          float[] temp = mTempMatrix;
          float[] currentMatrix = mMatrices;
          int index = mCurrentMatrixIndex;
          Matrix.multiplyMM(temp, 0, currentMatrix, index, matrix, offset);
          System.arraycopy(temp, 0, currentMatrix, index, 16);
      }
  
      @Override
      public void save() {
          save(SAVE_FLAG_ALL);
      }
  
      @Override
      public void save(int saveFlags) {
          boolean saveAlpha = (saveFlags & SAVE_FLAG_ALPHA) == SAVE_FLAG_ALPHA;
          if (saveAlpha) {
              float currentAlpha = getAlpha();
              mCurrentAlphaIndex++;
              if (mAlphas.length <= mCurrentAlphaIndex) {
                  mAlphas = Arrays.copyOf(mAlphas, mAlphas.length * 2);
              }
              mAlphas[mCurrentAlphaIndex] = currentAlpha;
          }
          boolean saveMatrix = (saveFlags & SAVE_FLAG_MATRIX) == SAVE_FLAG_MATRIX;
          if (saveMatrix) {
              int currentIndex = mCurrentMatrixIndex;
              mCurrentMatrixIndex += MATRIX_SIZE;
              if (mMatrices.length <= mCurrentMatrixIndex) {
                  mMatrices = Arrays.copyOf(mMatrices, mMatrices.length * 2);
              }
              System.arraycopy(mMatrices, currentIndex, mMatrices, mCurrentMatrixIndex, MATRIX_SIZE);
          }
          mSaveFlags.add(saveFlags);
      }
  
      @Override
      public void restore() {
          int restoreFlags = mSaveFlags.removeLast();
          boolean restoreAlpha = (restoreFlags & SAVE_FLAG_ALPHA) == SAVE_FLAG_ALPHA;
          if (restoreAlpha) {
              mCurrentAlphaIndex--;
          }
          boolean restoreMatrix = (restoreFlags & SAVE_FLAG_MATRIX) == SAVE_FLAG_MATRIX;
          if (restoreMatrix) {
              mCurrentMatrixIndex -= MATRIX_SIZE;
          }
      }
  
      @Override
      public void drawLine(float x1, float y1, float x2, float y2, GLPaint paint) {
          draw(GLES20.GL_LINE_STRIP, OFFSET_DRAW_LINE, COUNT_LINE_VERTEX, x1, y1, x2 - x1, y2 - y1,
                  paint);
          mCountDrawLine++;
      }
  
      @Override
      public void drawRect(float x, float y, float width, float height, GLPaint paint) {
          draw(GLES20.GL_LINE_LOOP, OFFSET_DRAW_RECT, COUNT_RECT_VERTEX, x, y, width, height, paint);
          mCountDrawLine++;
      }
  
      private void draw(int type, int offset, int count, float x, float y, float width, float height,
              GLPaint paint) {
          draw(type, offset, count, x, y, width, height, paint.getColor(), paint.getLineWidth());
      }
  
      private void draw(int type, int offset, int count, float x, float y, float width, float height,
              int color, float lineWidth) {
          prepareDraw(offset, color, lineWidth);
          draw(mDrawParameters, type, count, x, y, width, height);
      }
  
      private void prepareDraw(int offset, int color, float lineWidth) {
          GLES20.glUseProgram(mDrawProgram);
          checkError();
          if (lineWidth > 0) {
              GLES20.glLineWidth(lineWidth);
              checkError();
          }
          float[] colorArray = getColor(color);
          boolean blendingEnabled = (colorArray[3] < 1f);
          enableBlending(blendingEnabled);
          if (blendingEnabled) {
              GLES20.glBlendColor(colorArray[0], colorArray[1], colorArray[2], colorArray[3]);
              checkError();
          }
  
          GLES20.glUniform4fv(mDrawParameters[INDEX_COLOR].handle, 1, colorArray, 0);
          setPosition(mDrawParameters, offset);
          checkError();
      }
  
      private float[] getColor(int color) {
          float alpha = ((color >>> 24) & 0xFF) / 255f * getAlpha();
          float red = ((color >>> 16) & 0xFF) / 255f * alpha;
          float green = ((color >>> 8) & 0xFF) / 255f * alpha;
          float blue = (color & 0xFF) / 255f * alpha;
          mTempColor[0] = red;
          mTempColor[1] = green;
          mTempColor[2] = blue;
          mTempColor[3] = alpha;
          return mTempColor;
      }
  
      private void enableBlending(boolean enableBlending) {
          if (enableBlending) {
              GLES20.glEnable(GLES20.GL_BLEND);
              checkError();
          } else {
              GLES20.glDisable(GLES20.GL_BLEND);
              checkError();
          }
      }
  
      private void setPosition(ShaderParameter[] params, int offset) {
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mBoxCoordinates);
          checkError();
          GLES20.glVertexAttribPointer(params[INDEX_POSITION].handle, COORDS_PER_VERTEX,
                  GLES20.GL_FLOAT, false, VERTEX_STRIDE, offset * VERTEX_STRIDE);
          checkError();
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
          checkError();
      }
  
      private void draw(ShaderParameter[] params, int type, int count, float x, float y, float width,
              float height) {
          setMatrix(params, x, y, width, height);
          int positionHandle = params[INDEX_POSITION].handle;
          GLES20.glEnableVertexAttribArray(positionHandle);
          checkError();
          GLES20.glDrawArrays(type, 0, count);
          checkError();
          GLES20.glDisableVertexAttribArray(positionHandle);
          checkError();
      }
  
      private void setMatrix(ShaderParameter[] params, float x, float y, float width, float height) {
          Matrix.translateM(mTempMatrix, 0, mMatrices, mCurrentMatrixIndex, x, y, 0f);
          Matrix.scaleM(mTempMatrix, 0, width, height, 1f);
          Matrix.multiplyMM(mTempMatrix, MATRIX_SIZE, mProjectionMatrix, 0, mTempMatrix, 0);
          GLES20.glUniformMatrix4fv(params[INDEX_MATRIX].handle, 1, false, mTempMatrix, MATRIX_SIZE);
          checkError();
      }
  
      @Override
      public void fillRect(float x, float y, float width, float height, int color) {
          draw(GLES20.GL_TRIANGLE_STRIP, OFFSET_FILL_RECT, COUNT_FILL_VERTEX, x, y, width, height,
                  color, 0f);
          mCountFillRect++;
      }
  
      @Override
      public void drawTexture(BasicTexture texture, int x, int y, int width, int height) {
          if (width <= 0 || height <= 0) {
              return;
          }
          copyTextureCoordinates(texture, mTempSourceRect);
          mTempTargetRect.set(x, y, x + width, y + height);
          convertCoordinate(mTempSourceRect, mTempTargetRect, texture);
          drawTextureRect(texture, mTempSourceRect, mTempTargetRect);
      }
  
      private static void copyTextureCoordinates(BasicTexture texture, RectF outRect) {
          int left = 0;
          int top = 0;
          int right = texture.getWidth();
          int bottom = texture.getHeight();
          if (texture.hasBorder()) {
              left = 1;
              top = 1;
              right -= 1;
              bottom -= 1;
          }
          outRect.set(left, top, right, bottom);
      }
  
      @Override
      public void drawTexture(BasicTexture texture, RectF source, RectF target) {
          if (target.width() <= 0 || target.height() <= 0) {
              return;
          }
          mTempSourceRect.set(source);
          mTempTargetRect.set(target);
  
          convertCoordinate(mTempSourceRect, mTempTargetRect, texture);
          drawTextureRect(texture, mTempSourceRect, mTempTargetRect);
      }
  
      @Override
      public void drawTexture(BasicTexture texture, float[] textureTransform, int x, int y, int w,
              int h) {
          if (w <= 0 || h <= 0) {
              return;
          }
          mTempTargetRect.set(x, y, x + w, y + h);
          drawTextureRect(texture, textureTransform, mTempTargetRect);
      }
  
      private void drawTextureRect(BasicTexture texture, RectF source, RectF target) {
          setTextureMatrix(source);
          drawTextureRect(texture, mTempTextureMatrix, target);
      }
  
      private void setTextureMatrix(RectF source) {
          mTempTextureMatrix[0] = source.width();
          mTempTextureMatrix[5] = source.height();
          mTempTextureMatrix[12] = source.left;
          mTempTextureMatrix[13] = source.top;
      }
  
      // This function changes the source coordinate to the texture coordinates.
      // It also clips the source and target coordinates if it is beyond the
      // bound of the texture.
      private static void convertCoordinate(RectF source, RectF target, BasicTexture texture) {
          int width = texture.getWidth();
          int height = texture.getHeight();
          int texWidth = texture.getTextureWidth();
          int texHeight = texture.getTextureHeight();
          // Convert to texture coordinates
          source.left /= texWidth;
          source.right /= texWidth;
          source.top /= texHeight;
          source.bottom /= texHeight;
  
          // Clip if the rendering range is beyond the bound of the texture.
          float xBound = (float) width / texWidth;
          if (source.right > xBound) {
              target.right = target.left + target.width() * (xBound - source.left) / source.width();
              source.right = xBound;
          }
          float yBound = (float) height / texHeight;
          if (source.bottom > yBound) {
              target.bottom = target.top + target.height() * (yBound - source.top) / source.height();
              source.bottom = yBound;
          }
      }
  
      private void drawTextureRect(BasicTexture texture, float[] textureMatrix, RectF target) {
          ShaderParameter[] params = prepareTexture(texture);
          setPosition(params, OFFSET_FILL_RECT);
          GLES20.glUniformMatrix4fv(params[INDEX_TEXTURE_MATRIX].handle, 1, false, textureMatrix, 0);
          checkError();
          if (texture.isFlippedVertically()) {
              save(SAVE_FLAG_MATRIX);
              translate(0, target.centerY());
              scale(1, -1, 1);
              translate(0, -target.centerY());
          }
          draw(params, GLES20.GL_TRIANGLE_STRIP, COUNT_FILL_VERTEX, target.left, target.top,
                  target.width(), target.height());
          if (texture.isFlippedVertically()) {
              restore();
          }
          mCountTextureRect++;
      }
  
      private ShaderParameter[] prepareTexture(BasicTexture texture) {
          ShaderParameter[] params;
          int program;
          if (texture.getTarget() == GLES20.GL_TEXTURE_2D) {
              params = mTextureParameters;
              program = mTextureProgram;
          } else {
              params = mOesTextureParameters;
              program = mOesTextureProgram;
          }
          prepareTexture(texture, program, params);
          return params;
      }
  
      private void prepareTexture(BasicTexture texture, int program, ShaderParameter[] params) {
          GLES20.glUseProgram(program);
          checkError();
          enableBlending(!texture.isOpaque() || getAlpha() < OPAQUE_ALPHA);
          GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
          checkError();
          texture.onBind(this);
          GLES20.glBindTexture(texture.getTarget(), texture.getId());
          checkError();
          GLES20.glUniform1i(params[INDEX_TEXTURE_SAMPLER].handle, 0);
          checkError();
          GLES20.glUniform1f(params[INDEX_ALPHA].handle, getAlpha());
          checkError();
      }
  
      @Override
      public void drawMesh(BasicTexture texture, int x, int y, int xyBuffer, int uvBuffer,
              int indexBuffer, int indexCount) {
          prepareTexture(texture, mMeshProgram, mMeshParameters);
  
          GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
          checkError();
  
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, xyBuffer);
          checkError();
          int positionHandle = mMeshParameters[INDEX_POSITION].handle;
          GLES20.glVertexAttribPointer(positionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false,
                  VERTEX_STRIDE, 0);
          checkError();
  
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, uvBuffer);
          checkError();
          int texCoordHandle = mMeshParameters[INDEX_TEXTURE_COORD].handle;
          GLES20.glVertexAttribPointer(texCoordHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT,
                  false, VERTEX_STRIDE, 0);
          checkError();
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
          checkError();
  
          GLES20.glEnableVertexAttribArray(positionHandle);
          checkError();
          GLES20.glEnableVertexAttribArray(texCoordHandle);
          checkError();
  
          setMatrix(mMeshParameters, x, y, 1, 1);
          GLES20.glDrawElements(GLES20.GL_TRIANGLE_STRIP, indexCount, GLES20.GL_UNSIGNED_BYTE, 0);
          checkError();
  
          GLES20.glDisableVertexAttribArray(positionHandle);
          checkError();
          GLES20.glDisableVertexAttribArray(texCoordHandle);
          checkError();
          GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);
          checkError();
          mCountDrawMesh++;
      }
  
      @Override
      public void drawMixed(BasicTexture texture, int toColor, float ratio, int x, int y, int w, int h) {
          copyTextureCoordinates(texture, mTempSourceRect);
          mTempTargetRect.set(x, y, x + w, y + h);
          drawMixed(texture, toColor, ratio, mTempSourceRect, mTempTargetRect);
      }
  
      @Override
      public void drawMixed(BasicTexture texture, int toColor, float ratio, RectF source, RectF target) {
          if (target.width() <= 0 || target.height() <= 0) {
              return;
          }
          save(SAVE_FLAG_ALPHA);
  
          float currentAlpha = getAlpha();
          float cappedRatio = Math.min(1f, Math.max(0f, ratio));
  
          float textureAlpha = (1f - cappedRatio) * currentAlpha;
          setAlpha(textureAlpha);
          drawTexture(texture, source, target);
  
          float colorAlpha = cappedRatio * currentAlpha;
          setAlpha(colorAlpha);
          fillRect(target.left, target.top, target.width(), target.height(), toColor);
  
          restore();
      }
  
      @Override
      public boolean unloadTexture(BasicTexture texture) {
          boolean unload = texture.isLoaded();
          if (unload) {
              synchronized (mUnboundTextures) {
                  mUnboundTextures.add(texture.getId());
              }
          }
          return unload;
      }
  
      @Override
      public void deleteBuffer(int bufferId) {
          synchronized (mUnboundTextures) {
              mDeleteBuffers.add(bufferId);
          }
      }
  
      @Override
      public void deleteRecycledResources() {
          synchronized (mUnboundTextures) {
              IntArray ids = mUnboundTextures;
              if (mUnboundTextures.size() > 0) {
                  mGLId.glDeleteTextures(null, ids.size(), ids.getInternalArray(), 0);
                  ids.clear();
              }
  
              ids = mDeleteBuffers;
              if (ids.size() > 0) {
                  mGLId.glDeleteBuffers(null, ids.size(), ids.getInternalArray(), 0);
                  ids.clear();
              }
          }
      }
  
      @Override
      public void dumpStatisticsAndClear() {
          String line = String.format("MESH:%d, TEX_RECT:%d, FILL_RECT:%d, LINE:%d", mCountDrawMesh,
                  mCountTextureRect, mCountFillRect, mCountDrawLine);
          mCountDrawMesh = 0;
          mCountTextureRect = 0;
          mCountFillRect = 0;
          mCountDrawLine = 0;
          Log.d(TAG, line);
      }
  
      @Override
      public void endRenderTarget() {
          RawTexture oldTexture = mTargetTextures.remove(mTargetTextures.size() - 1);
          RawTexture texture = getTargetTexture();
          setRenderTarget(oldTexture, texture);
          restore(); // restore matrix and alpha
      }
  
      @Override
      public void beginRenderTarget(RawTexture texture) {
          save(); // save matrix and alpha and blending
          RawTexture oldTexture = getTargetTexture();
          mTargetTextures.add(texture);
          setRenderTarget(oldTexture, texture);
      }
  
      private RawTexture getTargetTexture() {
          return mTargetTextures.get(mTargetTextures.size() - 1);
      }
  
      private void setRenderTarget(BasicTexture oldTexture, RawTexture texture) {
          if (oldTexture == null && texture != null) {
              GLES20.glGenFramebuffers(1, mFrameBuffer, 0);
              checkError();
              GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, mFrameBuffer[0]);
              checkError();
          } else if (oldTexture != null && texture == null) {
              GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
              checkError();
              GLES20.glDeleteFramebuffers(1, mFrameBuffer, 0);
              checkError();
          }
  
          if (texture == null) {
              setSize(mScreenWidth, mScreenHeight);
          } else {
              setSize(texture.getWidth(), texture.getHeight());
  
              if (!texture.isLoaded()) {
                  texture.prepare(this);
              }
  
              GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0,
                      texture.getTarget(), texture.getId(), 0);
              checkError();
  
              checkFramebufferStatus();
          }
      }
  
      private static void checkFramebufferStatus() {
          int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER);
          if (status != GLES20.GL_FRAMEBUFFER_COMPLETE) {
              String msg = "";
              switch (status) {
                  case GLES20.GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
                      msg = "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT";
                      break;
                  case GLES20.GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS:
                      msg = "GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS";
                      break;
                  case GLES20.GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
                      msg = "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT";
                      break;
                  case GLES20.GL_FRAMEBUFFER_UNSUPPORTED:
                      msg = "GL_FRAMEBUFFER_UNSUPPORTED";
                      break;
              }
              throw new RuntimeException(msg + ":" + Integer.toHexString(status));
          }
      }
  
      @Override
      public void setTextureParameters(BasicTexture texture) {
          int target = texture.getTarget();
          GLES20.glBindTexture(target, texture.getId());
          checkError();
          GLES20.glTexParameteri(target, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
          GLES20.glTexParameteri(target, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
          GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
          GLES20.glTexParameterf(target, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
      }
  
      @Override
      public void initializeTextureSize(BasicTexture texture, int format, int type) {
          int target = texture.getTarget();
          GLES20.glBindTexture(target, texture.getId());
          checkError();
          int width = texture.getTextureWidth();
          int height = texture.getTextureHeight();
          GLES20.glTexImage2D(target, 0, format, width, height, 0, format, type, null);
      }
  
      @Override
      public void initializeTexture(BasicTexture texture, Bitmap bitmap) {
          int target = texture.getTarget();
          GLES20.glBindTexture(target, texture.getId());
          checkError();
          GLUtils.texImage2D(target, 0, bitmap, 0);
      }
  
      @Override
      public void texSubImage2D(BasicTexture texture, int xOffset, int yOffset, Bitmap bitmap,
              int format, int type) {
          int target = texture.getTarget();
          GLES20.glBindTexture(target, texture.getId());
          checkError();
          GLUtils.texSubImage2D(target, 0, xOffset, yOffset, bitmap, format, type);
      }
  
      @Override
      public int uploadBuffer(FloatBuffer buf) {
          return uploadBuffer(buf, FLOAT_SIZE);
      }
  
      @Override
      public int uploadBuffer(ByteBuffer buf) {
          return uploadBuffer(buf, 1);
      }
  
      private int uploadBuffer(Buffer buffer, int elementSize) {
          mGLId.glGenBuffers(1, mTempIntArray, 0);
          checkError();
          int bufferId = mTempIntArray[0];
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, bufferId);
          checkError();
          GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, buffer.capacity() * elementSize, buffer,
                  GLES20.GL_STATIC_DRAW);
          checkError();
          return bufferId;
      }
  
      public static void checkError() {
          int error = GLES20.glGetError();
          if (error != 0) {
              Throwable t = new Throwable();
              Log.e(TAG, "GL error: " + error, t);
          }
      }
  
      @SuppressWarnings("unused")
      private static void printMatrix(String message, float[] m, int offset) {
          StringBuilder b = new StringBuilder(message);
          for (int i = 0; i < MATRIX_SIZE; i++) {
              b.append(' ');
              if (i % 4 == 0) {
                  b.append('\n');
              }
              b.append(m[offset + i]);
          }
          Log.v(TAG, b.toString());
      }
  
      @Override
      public void recoverFromLightCycle() {
          GLES20.glViewport(0, 0, mWidth, mHeight);
          GLES20.glDisable(GLES20.GL_DEPTH_TEST);
          GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA);
          checkError();
      }
  
      @Override
      public void getBounds(Rect bounds, int x, int y, int width, int height) {
          Matrix.translateM(mTempMatrix, 0, mMatrices, mCurrentMatrixIndex, x, y, 0f);
          Matrix.scaleM(mTempMatrix, 0, width, height, 1f);
          Matrix.multiplyMV(mTempMatrix, MATRIX_SIZE, mTempMatrix, 0, BOUNDS_COORDINATES, 0);
          Matrix.multiplyMV(mTempMatrix, MATRIX_SIZE + 4, mTempMatrix, 0, BOUNDS_COORDINATES, 4);
          bounds.left = Math.round(mTempMatrix[MATRIX_SIZE]);
          bounds.right = Math.round(mTempMatrix[MATRIX_SIZE + 4]);
          bounds.top = Math.round(mTempMatrix[MATRIX_SIZE + 1]);
          bounds.bottom = Math.round(mTempMatrix[MATRIX_SIZE + 5]);
          bounds.sort();
      }
  
      @Override
      public GLId getGLId() {
          return mGLId;
      }
  }
  