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;
  
  
  /**
   * The purpose of this class hierarchy is to abstract different bitmap implementations across
   * platforms into a standard interface for requesting greyscale luminance values. The interface
   * only provides immutable methods; therefore crop and rotation create copies. This is to ensure
   * that one Reader does not modify the original luminance source and leave it in an unknown state
   * for other Readers in the chain.
   *
   * @author dswitkin@google.com (Daniel Switkin)
   */
  public abstract class LuminanceSource {
  
      private final int width;
      private final int height;
  
      protected LuminanceSource(int width, int height) {
          this.width = width;
          this.height = height;
      }
  
      /**
       * Fetches one row of luminance data from the underlying platform's bitmap. Values range from
       * 0 (black) to 255 (white). Because Java does not have an unsigned byte type, callers will have
       * to bitwise and with 0xff for each value. It is preferable for implementations of this method
       * to only fetch this row rather than the whole image, since no 2D Readers may be installed and
       * getMatrix() may never be called.
       *
       * @param y   The row to fetch, which must be in [0,getHeight())
       * @param row An optional preallocated array. If null or too small, it will be ignored.
       *            Always use the returned object, and ignore the .length of the array.
       * @return An array containing the luminance data.
       */
      public abstract byte[] getRow(int y, byte[] row);
  
      /**
       * Fetches luminance data for the underlying bitmap. Values should be fetched using:
       * {@code int luminance = array[y * width + x] & 0xff}
       *
       * @return A row-major 2D array of luminance values. Do not use result.length as it may be
       * larger than width * height bytes on some platforms. Do not modify the contents
       * of the result.
       */
      public abstract byte[] getMatrix();
  
      /**
       * @return The width of the bitmap.
       */
      public final int getWidth() {
          return width;
      }
  
      /**
       * @return The height of the bitmap.
       */
      public final int getHeight() {
          return height;
      }
  
      /**
       * @return Whether this subclass supports cropping.
       */
      public boolean isCropSupported() {
          return false;
      }
  
      /**
       * Returns a new object with cropped image data. Implementations may keep a reference to the
       * original data rather than a copy. Only callable if isCropSupported() is true.
       *
       * @param left   The left coordinate, which must be in [0,getWidth())
       * @param top    The top coordinate, which must be in [0,getHeight())
       * @param width  The width of the rectangle to crop.
       * @param height The height of the rectangle to crop.
       * @return A cropped version of this object.
       */
      public LuminanceSource crop(int left, int top, int width, int height) {
          throw new UnsupportedOperationException("This luminance source does not support cropping.");
      }
  
      /**
       * @return Whether this subclass supports counter-clockwise rotation.
       */
      public boolean isRotateSupported() {
          return false;
      }
  
      /**
       * @return a wrapper of this {@code LuminanceSource} which inverts the luminances it returns -- black becomes
       * white and vice versa, and each value becomes (255-value).
       */
      public LuminanceSource invert() {
          return new InvertedLuminanceSource(this);
      }
  
      /**
       * Returns a new object with rotated image data by 90 degrees counterclockwise.
       * Only callable if {@link #isRotateSupported()} is true.
       *
       * @return A rotated version of this object.
       */
      public LuminanceSource rotateCounterClockwise() {
          throw new UnsupportedOperationException("This luminance source does not support rotation by 90 degrees.");
      }
  
      /**
       * Returns a new object with rotated image data by 45 degrees counterclockwise.
       * Only callable if {@link #isRotateSupported()} is true.
       *
       * @return A rotated version of this object.
       */
      public LuminanceSource rotateCounterClockwise45() {
          throw new UnsupportedOperationException("This luminance source does not support rotation by 45 degrees.");
      }
  
      @Override
      public final String toString() {
          byte[] row = new byte[width];
          StringBuilder result = new StringBuilder(height * (width + 1));
          for (int y = 0; y < height; y++) {
              row = getRow(y, row);
              for (int x = 0; x < width; x++) {
                  int luminance = row[x] & 0xFF;
                  char c;
                  if (luminance < 0x40) {
                      c = '#';
                  } else if (luminance < 0x80) {
                      c = '+';
                  } else if (luminance < 0xC0) {
                      c = '.';
                  } else {
                      c = ' ';
                  }
                  result.append(c);
              }
              result.append('\n');
          }
          return result.toString();
      }
  }
  