content: /*
   * Copyright (C) 2012 CyberAgent
   *
   * 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 jp.co.cyberagent.android.gpuimage;
  
  import android.opengl.GLES20;
  
  /**
   * Changes the contrast of the image.<br>
   * <br>
   * contrast value ranges from 0.0 to 4.0, with 1.0 as the normal level
   */
  public class GPUImageContrastFilter extends GPUImageFilter {
      public static final String CONTRAST_FRAGMENT_SHADER = "" +
              "varying highp vec2 textureCoordinate;\n" + 
              " \n" + 
              " uniform sampler2D inputImageTexture;\n" + 
              " uniform lowp float contrast;\n" + 
              " \n" + 
              " void main()\n" + 
              " {\n" + 
              "     lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" + 
              "     \n" + 
              "     gl_FragColor = vec4(((textureColor.rgb - vec3(0.5)) * contrast + vec3(0.5)), textureColor.w);\n" + 
              " }";
  
      private int mContrastLocation;
      private float mContrast;
  
      public GPUImageContrastFilter() {
          this(1.2f);
      }
      
      public GPUImageContrastFilter(float contrast) {
          super(NO_FILTER_VERTEX_SHADER, CONTRAST_FRAGMENT_SHADER);
          mContrast = contrast;
      }
  
      @Override
      public void onInit() {
          super.onInit();
          mContrastLocation = GLES20.glGetUniformLocation(getProgram(), "contrast");
      }
  
      @Override
      public void onInitialized() {
          super.onInitialized();
          setContrast(mContrast);
      }
  
      public void setContrast(final float contrast) {
          mContrast = contrast;
          setFloat(mContrastLocation, mContrast);
      }
  }
  