content: package org.opencv.core;
  
  import java.util.Arrays;
  import java.util.List;
  
  import org.opencv.core.KeyPoint;
  
  public class MatOfKeyPoint extends Mat {
      // 32FC7
      private static final int _depth = CvType.CV_32F;
      private static final int _channels = 7;
  
      public MatOfKeyPoint() {
          super();
      }
  
      protected MatOfKeyPoint(long addr) {
          super(addr);
          if( !empty() && checkVector(_channels, _depth) < 0 )
              throw new IllegalArgumentException("Incompatible Mat");
          //FIXME: do we need release() here?
      }
  
      public static MatOfKeyPoint fromNativeAddr(long addr) {
          return new MatOfKeyPoint(addr);
      }
  
      public MatOfKeyPoint(Mat m) {
          super(m, Range.all());
          if( !empty() && checkVector(_channels, _depth) < 0 )
              throw new IllegalArgumentException("Incompatible Mat");
          //FIXME: do we need release() here?
      }
  
      public MatOfKeyPoint(KeyPoint...a) {
          super();
          fromArray(a);
      }
  
      public void alloc(int elemNumber) {
          if(elemNumber>0)
              super.create(elemNumber, 1, CvType.makeType(_depth, _channels));
      }
  
      public void fromArray(KeyPoint...a) {
          if(a==null || a.length==0)
              return;
          int num = a.length;
          alloc(num);
          float buff[] = new float[num * _channels];
          for(int i=0; i<num; i++) {
              KeyPoint kp = a[i];
              buff[_channels*i+0] = (float) kp.pt.x;
              buff[_channels*i+1] = (float) kp.pt.y;
              buff[_channels*i+2] = kp.size;
              buff[_channels*i+3] = kp.angle;
              buff[_channels*i+4] = kp.response;
              buff[_channels*i+5] = kp.octave;
              buff[_channels*i+6] = kp.class_id;
          }
          put(0, 0, buff); //TODO: check ret val!
      }
  
      public KeyPoint[] toArray() {
          int num = (int) total();
          KeyPoint[] a = new KeyPoint[num];
          if(num == 0)
              return a;
          float buff[] = new float[num * _channels];
          get(0, 0, buff); //TODO: check ret val!
          for(int i=0; i<num; i++)
              a[i] = new KeyPoint( buff[_channels*i+0], buff[_channels*i+1], buff[_channels*i+2], buff[_channels*i+3],
                                   buff[_channels*i+4], (int) buff[_channels*i+5], (int) buff[_channels*i+6] );
          return a;
      }
  
      public void fromList(List<KeyPoint> lkp) {
          KeyPoint akp[] = lkp.toArray(new KeyPoint[0]);
          fromArray(akp);
      }
  
      public List<KeyPoint> toList() {
          KeyPoint[] akp = toArray();
          return Arrays.asList(akp);
      }
  }
  