content: /*
   * Copyright 2009 ZXing authors
   *
   * 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 com.google.zxing.decoding;
  
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  
  import com.google.zxing.LuminanceSource;
  
  import java.io.FileNotFoundException;
  
  /**
   * This class is used to help decode images from files which arrive as RGB data
   * from Android bitmaps. It does not support cropping or rotation.
   *
   */
  public final class RGBLuminanceSource extends LuminanceSource {
  
      private final byte[] luminances;
  
      public RGBLuminanceSource(String path) throws FileNotFoundException {
          this(loadBitmap(path));
      }
  
      public RGBLuminanceSource(Bitmap bitmap) {
          super(bitmap.getWidth(), bitmap.getHeight());
  
          int width = bitmap.getWidth();
          int height = bitmap.getHeight();
  
          int[] pixels = new int[width * height];
          bitmap.getPixels(pixels, 0, width, 0, 0, width, height);
  
          // In order to measure pure decoding speed, we convert the entire image
          // to a greyscale array
          // up front, which is the same as the Y channel of the
          // YUVLuminanceSource in the real app.
          luminances = new byte[width * height];
          for (int y = 0; y < height; y++) {
              int offset = y * width;
              for (int x = 0; x < width; x++) {
                  int pixel = pixels[offset + x];
                  int r = (pixel >> 16) & 0xff;
                  int g = (pixel >> 8) & 0xff;
                  int b = pixel & 0xff;
                  if (r == g && g == b) {
                      // Image is already greyscale, so pick any channel.
                      luminances[offset + x] = (byte) r;
                  } else {
                      // Calculate luminance cheaply, favoring green.
                      luminances[offset + x] = (byte) ((r + g + g + b) >> 2);
                  }
              }
          }
      }
  
  
      @Override
      public byte[] getRow(int y, byte[] row) {
          if (y < 0 || y >= getHeight()) {
              throw new IllegalArgumentException("Requested row is outside the image: " + y);
          }
          int width = getWidth();
          if (row == null || row.length < width) {
              row = new byte[width];
          }
  
          System.arraycopy(luminances, y * width, row, 0, width);
          return row;
      }
  
      // Since this class does not support cropping, the underlying byte array
      // already contains
      // exactly what the caller is asking for, so give it to them without a copy.
      @Override
      public byte[] getMatrix() {
          return luminances;
      }
  
      private static Bitmap loadBitmap(String path) throws FileNotFoundException {
          Bitmap bitmap = BitmapFactory.decodeFile(path);
          if (bitmap == null) {
              throw new FileNotFoundException("Couldn't open " + path);
          }
          return bitmap;
      }
  
  }
  