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;
  	}
  
  }
  