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.ailiwean.core.zxing.core;
  
  /**
   * This class is used to help decode images from files which arrive as RGB data from
   * an ARGB pixel array. It does not support rotation.
   *
   * @author dswitkin@google.com (Daniel Switkin)
   * @author Betaminos
   */
  public final class RGBLuminanceSource extends LuminanceSource {
  
      private final byte[] luminances;
      private final int dataWidth;
      private final int dataHeight;
      private final int left;
      private final int top;
  
      public RGBLuminanceSource(int width, int height, int[] pixels) {
          super(width, height);
  
          dataWidth = width;
          dataHeight = height;
          left = 0;
          top = 0;
  
          // 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.
          //
          // Total number of pixels suffices, can ignore shape
          int size = width * height;
          luminances = new byte[size];
          for (int offset = 0; offset < size; offset++) {
              int pixel = pixels[offset];
              int r = (pixel >> 16) & 0xff; // red
              int g2 = (pixel >> 7) & 0x1fe; // 2 * green
              int b = pixel & 0xff; // blue
              // Calculate green-favouring average cheaply
              luminances[offset] = (byte) ((r + g2 + b) / 4);
          }
      }
  
      public RGBLuminanceSource(byte[] pixels,
                                int dataWidth,
                                int dataHeight,
                                int left,
                                int top,
                                int width,
                                int height) {
          super(width, height);
          if (left + width > dataWidth || top + height > dataHeight) {
              throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
          }
          this.luminances = pixels;
          this.dataWidth = dataWidth;
          this.dataHeight = dataHeight;
          this.left = left;
          this.top = top;
      }
  
      @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];
          }
          int offset = (y + top) * dataWidth + left;
          System.arraycopy(luminances, offset, row, 0, width);
          return row;
      }
  
      @Override
      public byte[] getMatrix() {
          int width = getWidth();
          int height = getHeight();
  
          // If the caller asks for the entire underlying image, save the copy and give them the
          // original data. The docs specifically warn that result.length must be ignored.
          if (width == dataWidth && height == dataHeight) {
              return luminances;
          }
  
          int area = width * height;
          byte[] matrix = new byte[area];
          int inputOffset = top * dataWidth + left;
  
          // If the width matches the full width of the underlying data, perform a single copy.
          if (width == dataWidth) {
              System.arraycopy(luminances, inputOffset, matrix, 0, area);
              return matrix;
          }
  
          // Otherwise copy one cropped row at a time.
          for (int y = 0; y < height; y++) {
              int outputOffset = y * width;
              System.arraycopy(luminances, inputOffset, matrix, outputOffset, width);
              inputOffset += dataWidth;
          }
          return matrix;
      }
  
      @Override
      public boolean isCropSupported() {
          return true;
      }
  
      @Override
      public LuminanceSource crop(int left, int top, int width, int height) {
          return new RGBLuminanceSource(luminances,
                  dataWidth,
                  dataHeight,
                  this.left + left,
                  this.top + top,
                  width,
                  height);
      }
  
  }
  