How to get QR code from pictures on Android

 case CHOOSE_PIC:
          String[] proj = new String[]{};
          Cursor cursor = ().query((), proj, null, null, null);

          if(()){
            int columnIndex = ();
            (columnIndex);
            // Obtain the absolute path to get the QR code picture selected by the user            imgPath = (columnIndex);
          }
          ();

          //Get parsing results          Result ret = parseQRcodeBitmap(imgPath);
          if (ret==null){
            (,getString(.load_two_dimensional_error), Toast.LENGTH_LONG).show();
          }else {
// (,"Analysis result:" + (), Toast.LENGTH_LONG).show();            Intent intent = new Intent();
            (, ());
            (Activity.RESULT_OK, intent);
            (.fade_in, .fade_out);
            finish();
          }
          break;

//Analyze the QR code image, return the result encapsulated in the Result objectprivate  parseQRcodeBitmap(String bitmapPath){
  //Resolve conversion type UTF-8  Hashtable<DecodeHintType, String> hints = new Hashtable<DecodeHintType, String>();
  (DecodeHintType.CHARACTER_SET, "utf-8");
  //Get the picture to be parsed   options = new ();
  //If we set inJustDecodeBounds to true, then (String path, Options opt)  //It will not really return a Bitmap for you, it will only retrieve its width and height for you.   = true;
  //The bitmap is null at this time. After this code, and is the width and height we want  Bitmap bitmap = (bitmapPath,options);
  //The side length of the picture we want to take out now (the QR code picture is square) is set to 400 pixels  /**
    = 400;
    = 400;
    = false;
   bitmap = (bitmapPath, options);
   */
  //The above practice limits bitmap to the size we want, but does not save memory. If we want to save memory, we still need to use the inSimpleSize property   =  / 400;
  if( <= 0){
     = 1; //Prevent its value from being less than or equal to 0  }
  /**
    * Auxiliary memory saving settings
    *
    * = .ARGB_4444; // The default is .ARGB_8888
    * = true;
    * = true;
    */
   = false;
  bitmap = (bitmapPath, options);
  // Create a new RGBLuminanceSource object and pass the bitmap image to this object  RGBLuminanceSource rgbLuminanceSource = new RGBLuminanceSource(bitmap);
  //Convert the picture to binary picture  BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(rgbLuminanceSource));
  //Initialize the parsing object  QRCodeReader reader = new QRCodeReader();
  //Start the analysis  Result result = null;
  try {
    result = (binaryBitmap, hints);
  } catch (Exception e) {
    // TODO: handle exception
  }

  return result;
}

// Create a new RGBLuminanceSource object and pass the bitmap image to this objectRGBLuminanceSource rgbLuminanceSource = new RGBLuminanceSource(bitmap);
//Convert the picture to binary pictureBinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(rgbLuminanceSource));
//Initialize the parsing objectQRCodeReader reader = new QRCodeReader();

package .;
import ;

import ;
import ;

import ;

public class RGBLuminanceSource extends LuminanceSource {
  private final byte[] luminances;

  public RGBLuminanceSource(Bitmap bitmap) {
    super((), ());
    //Get the width and height of the picture    int width = ();
    int height = ();
    //Get the pixels of the image    int[] pixels = new int[width * height];
    //
    (pixels, 0, width, 0, 0, width, height);
    //In order to measure the pure decoding speed, we will front the entire image grayscale array, which is the same channel    // YUVLuminanceSource is used in real life.    //Get the number of bytes of pixel size    luminances = new byte[width * height];
    //Get the pixel color per point of the picture    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;
        //When the three color values ​​of a certain point are the same, the corresponding byte corresponding space is assigned to its value        if (r == g && g == b) {
          luminances[offset + x] = (byte) r;
        }
        //In other cases, the corresponding assignment of byte space is:        else {
          luminances[offset + x] = (byte) ((r + g + g + b) >> 2);
        }
      }
    }
  }

  public RGBLuminanceSource(String path) throws FileNotFoundException {
    this(loadBitmap(path));
  }


  @Override
  public byte[] getMatrix() {
    return luminances;
  }

  @Override
  public byte[] getRow(int arg0, byte[] arg1) {
    if (arg0 < 0 || arg0 >= getHeight()) {
      throw new IllegalArgumentException(
          "Requested row is outside the image: " + arg0);
    }
    int width = getWidth();
    if (arg1 == null ||  < width) {
      arg1 = new byte[width];
    }
    (luminances, arg0 * width, arg1, 0, width);
    return arg1;
  }

  private static Bitmap loadBitmap(String path) throws FileNotFoundException {
    Bitmap bitmap = (path);
    if (bitmap == null) {
      throw new FileNotFoundException("Couldn't open " + path);
    }
    return bitmap;
  }
}