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;
  
  /**
   * A hardware-accelerated 9-hit box blur of an image
   *
   * scaling: for the size of the applied blur, default of 1.0
   */
  public class GPUImageBoxBlurFilter extends GPUImageTwoPassTextureSamplingFilter {
      public static final String VERTEX_SHADER =
              "attribute vec4 position;\n" +
                      "attribute vec2 inputTextureCoordinate;\n" +
                      "\n" +
                      "uniform float texelWidthOffset; \n" +
                      "uniform float texelHeightOffset; \n" +
                      "\n" +
                      "varying vec2 centerTextureCoordinate;\n" +
                      "varying vec2 oneStepLeftTextureCoordinate;\n" +
                      "varying vec2 twoStepsLeftTextureCoordinate;\n" +
                      "varying vec2 oneStepRightTextureCoordinate;\n" +
                      "varying vec2 twoStepsRightTextureCoordinate;\n" +
                      "\n" +
                      "void main()\n" +
                      "{\n" +
                      "gl_Position = position;\n" +
                      "\n" +
                      "vec2 firstOffset = vec2(1.5 * texelWidthOffset, 1.5 * texelHeightOffset);\n" +
                      "vec2 secondOffset = vec2(3.5 * texelWidthOffset, 3.5 * texelHeightOffset);\n" +
                      "\n" +
                      "centerTextureCoordinate = inputTextureCoordinate;\n" +
                      "oneStepLeftTextureCoordinate = inputTextureCoordinate - firstOffset;\n" +
                      "twoStepsLeftTextureCoordinate = inputTextureCoordinate - secondOffset;\n" +
                      "oneStepRightTextureCoordinate = inputTextureCoordinate + firstOffset;\n" +
                      "twoStepsRightTextureCoordinate = inputTextureCoordinate + secondOffset;\n" +
                      "}\n";
  
      public static final String FRAGMENT_SHADER =
              "precision highp float;\n" +
                      "\n" +
                      "uniform sampler2D inputImageTexture;\n" +
                      "\n" +
                      "varying vec2 centerTextureCoordinate;\n" +
                      "varying vec2 oneStepLeftTextureCoordinate;\n" +
                      "varying vec2 twoStepsLeftTextureCoordinate;\n" +
                      "varying vec2 oneStepRightTextureCoordinate;\n" +
                      "varying vec2 twoStepsRightTextureCoordinate;\n" +
                      "\n" +
                      "void main()\n" +
                      "{\n" +
                      "lowp vec4 fragmentColor = texture2D(inputImageTexture, centerTextureCoordinate) * 0.2;\n" +
                      "fragmentColor += texture2D(inputImageTexture, oneStepLeftTextureCoordinate) * 0.2;\n" +
                      "fragmentColor += texture2D(inputImageTexture, oneStepRightTextureCoordinate) * 0.2;\n" +
                      "fragmentColor += texture2D(inputImageTexture, twoStepsLeftTextureCoordinate) * 0.2;\n" +
                      "fragmentColor += texture2D(inputImageTexture, twoStepsRightTextureCoordinate) * 0.2;\n" +
                      "\n" +
                      "gl_FragColor = fragmentColor;\n" +
                      "}\n";
  
      private float blurSize = 1f;
  
      /**
       * Construct new BoxBlurFilter with default blur size of 1.0.
       */
      public GPUImageBoxBlurFilter() {
          this(1f);
      }
  
  
      public GPUImageBoxBlurFilter(float blurSize) {
          super(VERTEX_SHADER, FRAGMENT_SHADER, VERTEX_SHADER, FRAGMENT_SHADER);
          this.blurSize = blurSize;
      }
  
      /**
       * A scaling for the size of the applied blur, default of 1.0
       *
       * @param blurSize
       */
      public void setBlurSize(float blurSize) {
          this.blurSize = blurSize;
          runOnDraw(new Runnable() {
              @Override
              public void run() {
                  initTexelOffsets();
              }
          });
      }
  
      @Override
      public float getVerticalTexelOffsetRatio() {
          return blurSize;
      }
  
      @Override
      public float getHorizontalTexelOffsetRatio() {
          return blurSize;
      }
  }
  