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.Filter;
  import android.filterfw.core.FilterContext;
  import android.filterfw.core.Frame;
  import android.filterfw.core.FrameFormat;
  import android.filterfw.core.GenerateFieldPort;
  import android.filterfw.core.Program;
  import android.filterfw.core.ShaderProgram;
  import android.filterfw.format.ImageFormat;
  
  import java.lang.Math;
  
  /**
   * @hide
   */
  public class FisheyeFilter extends Filter {
      private static final String TAG = "FisheyeFilter";
  
      // This parameter has range between 0 and 1. It controls the effect of radial distortion.
      // The larger the value, the more prominent the distortion effect becomes (a straight line
      // becomes a curve).
      @GenerateFieldPort(name = "scale", hasDefault = true)
      private float mScale = 0f;
  
      @GenerateFieldPort(name = "tile_size", hasDefault = true)
      private int mTileSize = 640;
  
      private Program mProgram;
  
      private int mWidth = 0;
      private int mHeight = 0;
      private int mTarget = FrameFormat.TARGET_UNSPECIFIED;
  
      // The constant min_dist, below, is an arbitrary number that gives good enough precision in
      // the center of the picture without affecting the fisheye effect noticeably.
      private static final String mFisheyeShader =
              "precision mediump float;\n" +
              "uniform sampler2D tex_sampler_0;\n" +
              "uniform vec2 scale;\n" +
              "uniform float alpha;\n" +
              "uniform float radius2;\n" +
              "uniform float factor;\n" +
              "varying vec2 v_texcoord;\n" +
              "void main() {\n" +
              "  const float m_pi_2 = 1.570963;\n" +
              "  const float min_dist = 0.01;\n" +
              "  vec2 coord = v_texcoord - vec2(0.5, 0.5);\n" +
              "  float dist = length(coord * scale);\n" +
              "  dist = max(dist, min_dist);\n" +
              "  float radian = m_pi_2 - atan(alpha * sqrt(radius2 - dist * dist), dist);\n" +
              "  float scalar = radian * factor / dist;\n" +
              "  vec2 new_coord = coord * scalar + vec2(0.5, 0.5);\n" +
              "  gl_FragColor = texture2D(tex_sampler_0, new_coord);\n" +
              "}\n";
  
      public FisheyeFilter(String name) {
          super(name);
      }
  
      @Override
      public void setupPorts() {
          addMaskedInputPort("image", ImageFormat.create(ImageFormat.COLORSPACE_RGBA));
          addOutputBasedOnInput("image", "image");
      }
  
      @Override
      public FrameFormat getOutputFormat(String portName, FrameFormat inputFormat) {
          return inputFormat;
      }
  
      public void initProgram(FilterContext context, int target) {
          switch (target) {
              case FrameFormat.TARGET_GPU:
                  ShaderProgram shaderProgram = new ShaderProgram(context, mFisheyeShader);
                  shaderProgram.setMaximumTileSize(mTileSize);
                  mProgram = shaderProgram;
                  break;
  
              default:
                  throw new RuntimeException("Filter FisheyeFilter does not support frames of " +
                      "target " + target + "!");
          }
          mTarget = target;
      }
  
      @Override
      public void process(FilterContext context) {
          // Get input frame
          Frame input = pullInput("image");
          FrameFormat inputFormat = input.getFormat();
  
          // Create output frame
          Frame output = context.getFrameManager().newFrame(inputFormat);
  
          // Create program if not created already
          if (mProgram == null || inputFormat.getTarget() != mTarget) {
              initProgram(context, inputFormat.getTarget());
          }
  
          // Check if the frame size has changed
          if (inputFormat.getWidth() != mWidth || inputFormat.getHeight() != mHeight) {
              updateFrameSize(inputFormat.getWidth(), inputFormat.getHeight());
          }
  
          // Process
          mProgram.process(input, output);
  
          // Push output
          pushOutput("image", output);
  
          // Release pushed frame
          output.release();
      }
  
      @Override
      public void fieldPortValueUpdated(String name, FilterContext context) {
          if (mProgram != null) {
              updateProgramParams();
          }
      }
  
      private void updateFrameSize(int width, int height) {
          mWidth = width;
          mHeight = height;
  
          updateProgramParams();
      }
  
      private void updateProgramParams() {
          final float pi = 3.14159265f;
          float scale[] = new float[2];
          if (mWidth > mHeight) {
            scale[0] = 1f;
            scale[1] = ((float) mHeight) / mWidth;
          } else {
            scale[0] = ((float) mWidth) / mHeight;
            scale[1] = 1f;
          }
          float alpha = mScale * 2.0f + 0.75f;
          float bound2 = 0.25f * (scale[0] * scale[0] + scale[1] * scale[1]);
          float bound = (float) Math.sqrt(bound2);
          float radius = 1.15f * bound;
          float radius2 = radius * radius;
          float max_radian = 0.5f * pi -
              (float) Math.atan(alpha / bound * (float) Math.sqrt(radius2 - bound2));
          float factor = bound / max_radian;
  
          mProgram.setHostValue("scale", scale);
          mProgram.setHostValue("radius2",radius2);
          mProgram.setHostValue("factor", factor);
          mProgram.setHostValue("alpha", alpha);
      }
  }
  