content: /*
   * Copyright (C) 2007 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.graphics;
  
  import java.util.Arrays;
  
  /**
   * 4x5 matrix for transforming the color and alpha components of a Bitmap.
   * The matrix can be passed as single array, and is treated as follows:
   *
   * <pre>
   *  [ a, b, c, d, e,
   *    f, g, h, i, j,
   *    k, l, m, n, o,
   *    p, q, r, s, t ]</pre>
   *
   * <p>
   * When applied to a color <code>[R, G, B, A]</code>, the resulting color
   * is computed as:
   * </p>
   *
   * <pre>
   *   R&rsquo; = a*R + b*G + c*B + d*A + e;
   *   G&rsquo; = f*R + g*G + h*B + i*A + j;
   *   B&rsquo; = k*R + l*G + m*B + n*A + o;
   *   A&rsquo; = p*R + q*G + r*B + s*A + t;</pre>
   *
   * <p>
   * That resulting color <code>[R&rsquo;, G&rsquo;, B&rsquo;, A&rsquo;]</code>
   * then has each channel clamped to the <code>0</code> to <code>255</code>
   * range.
   * </p>
   *
   * <p>
   * The sample ColorMatrix below inverts incoming colors by scaling each
   * channel by <code>-1</code>, and then shifting the result up by
   * <code>255</code> to remain in the standard color space.
   * </p>
   *
   * <pre>
   *   [ -1, 0, 0, 0, 255,
   *     0, -1, 0, 0, 255,
   *     0, 0, -1, 0, 255,
   *     0, 0, 0, 1, 0 ]</pre>
   */
  @SuppressWarnings({ "MismatchedReadAndWriteOfArray", "PointlessArithmeticExpression" })
  public class ColorMatrix {
      private final float[] mArray = new float[20];
  
      /**
       * Create a new colormatrix initialized to identity (as if reset() had
       * been called).
       */
      public ColorMatrix() {
          reset();
      }
  
      /**
       * Create a new colormatrix initialized with the specified array of values.
       */
      public ColorMatrix(float[] src) {
          System.arraycopy(src, 0, mArray, 0, 20);
      }
  
      /**
       * Create a new colormatrix initialized with the specified colormatrix.
       */
      public ColorMatrix(ColorMatrix src) {
          System.arraycopy(src.mArray, 0, mArray, 0, 20);
      }
  
      /**
       * Return the array of floats representing this colormatrix.
       */
      public final float[] getArray() { return mArray; }
  
      /**
       * Set this colormatrix to identity:
       * <pre>
       * [ 1 0 0 0 0   - red vector
       *   0 1 0 0 0   - green vector
       *   0 0 1 0 0   - blue vector
       *   0 0 0 1 0 ] - alpha vector
       * </pre>
       */
      public void reset() {
          final float[] a = mArray;
          Arrays.fill(a, 0);
          a[0] = a[6] = a[12] = a[18] = 1;
      }
  
      /**
       * Assign the src colormatrix into this matrix, copying all of its values.
       */
      public void set(ColorMatrix src) {
          System.arraycopy(src.mArray, 0, mArray, 0, 20);
      }
  
      /**
       * Assign the array of floats into this matrix, copying all of its values.
       */
      public void set(float[] src) {
          System.arraycopy(src, 0, mArray, 0, 20);
      }
  
      /**
       * Set this colormatrix to scale by the specified values.
       */
      public void setScale(float rScale, float gScale, float bScale,
                           float aScale) {
          final float[] a = mArray;
  
          for (int i = 19; i > 0; --i) {
              a[i] = 0;
          }
          a[0] = rScale;
          a[6] = gScale;
          a[12] = bScale;
          a[18] = aScale;
      }
  
      /**
       * Set the rotation on a color axis by the specified values.
       * <p>
       * <code>axis=0</code> correspond to a rotation around the RED color
       * <code>axis=1</code> correspond to a rotation around the GREEN color
       * <code>axis=2</code> correspond to a rotation around the BLUE color
       * </p>
       */
      public void setRotate(int axis, float degrees) {
          reset();
          double radians = degrees * Math.PI / 180d;
          float cosine = (float) Math.cos(radians);
          float sine = (float) Math.sin(radians);
          switch (axis) {
          // Rotation around the red color
          case 0:
              mArray[6] = mArray[12] = cosine;
              mArray[7] = sine;
              mArray[11] = -sine;
              break;
          // Rotation around the green color
          case 1:
              mArray[0] = mArray[12] = cosine;
              mArray[2] = -sine;
              mArray[10] = sine;
              break;
          // Rotation around the blue color
          case 2:
              mArray[0] = mArray[6] = cosine;
              mArray[1] = sine;
              mArray[5] = -sine;
              break;
          default:
              throw new RuntimeException();
          }
      }
  
      /**
       * Set this colormatrix to the concatenation of the two specified
       * colormatrices, such that the resulting colormatrix has the same effect
       * as applying matB and then applying matA.
       * <p>
       * It is legal for either matA or matB to be the same colormatrix as this.
       * </p>
       */
      public void setConcat(ColorMatrix matA, ColorMatrix matB) {
          float[] tmp;
          if (matA == this || matB == this) {
              tmp = new float[20];
          } else {
              tmp = mArray;
          }
  
          final float[] a = matA.mArray;
          final float[] b = matB.mArray;
          int index = 0;
          for (int j = 0; j < 20; j += 5) {
              for (int i = 0; i < 4; i++) {
                  tmp[index++] = a[j + 0] * b[i + 0] +  a[j + 1] * b[i + 5] +
                                 a[j + 2] * b[i + 10] + a[j + 3] * b[i + 15];
              }
              tmp[index++] = a[j + 0] * b[4] +  a[j + 1] * b[9] +
                             a[j + 2] * b[14] + a[j + 3] * b[19] +
                             a[j + 4];
          }
  
          if (tmp != mArray) {
              System.arraycopy(tmp, 0, mArray, 0, 20);
          }
      }
  
      /**
       * Concat this colormatrix with the specified prematrix.
       * <p>
       * This is logically the same as calling setConcat(this, prematrix);
       * </p>
       */
      public void preConcat(ColorMatrix prematrix) {
          setConcat(this, prematrix);
      }
  
      /**
       * Concat this colormatrix with the specified postmatrix.
       * <p>
       * This is logically the same as calling setConcat(postmatrix, this);
       * </p>
       */
      public void postConcat(ColorMatrix postmatrix) {
          setConcat(postmatrix, this);
      }
  
      ///////////////////////////////////////////////////////////////////////////
  
      /**
       * Set the matrix to affect the saturation of colors.
       *
       * @param sat A value of 0 maps the color to gray-scale. 1 is identity.
       */
      public void setSaturation(float sat) {
          reset();
          float[] m = mArray;
  
          final float invSat = 1 - sat;
          final float R = 0.213f * invSat;
          final float G = 0.715f * invSat;
          final float B = 0.072f * invSat;
  
          m[0] = R + sat; m[1] = G;       m[2] = B;
          m[5] = R;       m[6] = G + sat; m[7] = B;
          m[10] = R;      m[11] = G;      m[12] = B + sat;
      }
  
      /**
       * Set the matrix to convert RGB to YUV
       */
      public void setRGB2YUV() {
          reset();
          float[] m = mArray;
          // these coefficients match those in libjpeg
          m[0]  = 0.299f;    m[1]  = 0.587f;    m[2]  = 0.114f;
          m[5]  = -0.16874f; m[6]  = -0.33126f; m[7]  = 0.5f;
          m[10] = 0.5f;      m[11] = -0.41869f; m[12] = -0.08131f;
      }
  
      /**
       * Set the matrix to convert from YUV to RGB
       */
      public void setYUV2RGB() {
          reset();
          float[] m = mArray;
          // these coefficients match those in libjpeg
                                          m[2] = 1.402f;
          m[5] = 1;   m[6] = -0.34414f;   m[7] = -0.71414f;
          m[10] = 1;  m[11] = 1.772f;     m[12] = 0;
      }
  
      @Override
      public boolean equals(Object obj) {
          // if (obj == this) return true; -- NaN value would mean matrix != itself
          if (!(obj instanceof ColorMatrix)) {
              return false;
          }
  
          // we don't use Arrays.equals(), since that considers NaN == NaN
          final float[] other = ((ColorMatrix) obj).mArray;
          for (int i = 0; i < 20; i++) {
              if (other[i] != mArray[i]) {
                  return false;
              }
          }
          return true;
      }
  }
  