content: /*
   * Copyright (C) 2011 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 android.filterpacks.imageproc;
  
  import android.filterfw.core.FilterContext;
  import android.filterfw.core.FrameFormat;
  import android.filterfw.core.GenerateFieldPort;
  import android.filterfw.core.MutableFrameFormat;
  import android.filterfw.core.Program;
  import android.filterfw.core.ShaderProgram;
  import android.filterfw.format.ImageFormat;
  
  /**
   * @hide
   */
  public class ToGrayFilter extends SimpleImageFilter {
  
      @GenerateFieldPort(name = "invertSource", hasDefault = true)
      private boolean mInvertSource = false;
  
      @GenerateFieldPort(name = "tile_size", hasDefault = true)
      private int mTileSize = 640;
  
      private MutableFrameFormat mOutputFormat;
  
      private static final String mColorToGray4Shader =
              "precision mediump float;\n" +
              "uniform sampler2D tex_sampler_0;\n" +
              "varying vec2 v_texcoord;\n" +
              "void main() {\n" +
              "  vec4 color = texture2D(tex_sampler_0, v_texcoord);\n" +
              "  float y = dot(color, vec4(0.299, 0.587, 0.114, 0));\n" +
              "  gl_FragColor = vec4(y, y, y, color.a);\n" +
              "}\n";
  
      public ToGrayFilter(String name) {
          super(name, null);
      }
  
      @Override
      public void setupPorts() {
          addMaskedInputPort("image", ImageFormat.create(ImageFormat.COLORSPACE_RGBA,
                                                         FrameFormat.TARGET_GPU));
          addOutputBasedOnInput("image", "image");
      }
  
      @Override
      protected Program getNativeProgram(FilterContext context) {
          throw new RuntimeException("Native toGray not implemented yet!");
      }
  
      @Override
      protected Program getShaderProgram(FilterContext context) {
          int inputChannels = getInputFormat("image").getBytesPerSample();
          if (inputChannels != 4) {
              throw new RuntimeException("Unsupported GL input channels: " +
                                         inputChannels + "! Channels must be 4!");
          }
          ShaderProgram program = new ShaderProgram(context, mColorToGray4Shader);
          program.setMaximumTileSize(mTileSize);
          if (mInvertSource)
              program.setSourceRect(0.0f, 1.0f, 1.0f, -1.0f);
          return program;
      }
  
  }
  