我想实现以下的例子code question 通过使用OpenCV的的Java API。为贯彻落实 findContours（灰色，轮廓，CV_RETR_LIST，CV_CHAIN​​_APPROX_SIMPLE）; 在java中我用这个语法 Imgproc.findContours（灰色，轮廓，新材料（） ，Imgproc.RETR_LIST，Imgproc.CHAIN​​_APPROX_SIMPLE）; 。

I'm trying to implement the example code of the following question by using opencv java api. To implement findContours(gray, contours, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE); in java i used this syntax Imgproc.findContours(gray, contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);.

所以，现在的轮廓应该是名单，其中，MatOfPoint＆GT;轮廓=新的ArrayList＆LT; MatOfPoint＆GT;（）; ，而不是矢量＆lt;矢量＆lt; CV ::点＆GT; ＆GT;轮廓; 。

So now contours should be List<MatOfPoint> contours = new ArrayList<MatOfPoint>(); rather than vector<vector<cv::Point> > contours;.

那么我就需要实现这个 approxPolyDP（马太福音（轮廓[I]），约，弧长（马太福音（轮廓[I]），真）* 0.02，真）; 。在的Java API，Imgproc.approxPolyDP接受的说法是 approxPolyDP（MatOfPoint2f曲线，MatOfPoint2f approxCurve，双ε，布尔关）。我如何我可以转换M​​atOfPoint到MatOfPoint2f？

Then i need implement this approxPolyDP(Mat(contours[i]), approx, arcLength(Mat(contours[i]), true)*0.02, true);. In java api, Imgproc.approxPolyDP accept argument as approxPolyDP(MatOfPoint2f curve, MatOfPoint2f approxCurve, double epsilon, boolean closed). How i can i convert MatOfPoint to MatOfPoint2f?

或者是有没有办法使用的载体是相同的C ++实现这个接口。任何建议或样品code是大大AP preciated。

Or is there a way to use vectors as same as c++ interface to implement this. Any suggestion or sample code is greatly appreciated.

推荐答案

MatOfPoint2f不同于MatOfPoint只中的元素（分别为32位浮点和32位int）的类型。的可行的选择（虽然性能上的损失）是制造MatOfPoint2f实例并设置其元素（在循环中）等于源MatOfPoint的元素

MatOfPoint2f differs from MatOfPoint only in the type of the elements (32-bit float and 32-bit int respectively). The viable option (though with a performance penalty) is to create MatOfPoint2f instance and set its elements (in a loop) to be equal to the elements of of the source MatOfPoint.

有

 public void fromArray(Point... lp);
 public Point[] toArray();

在两种类的方法。

所以，你可以做到这

 /// Source variable
 MatOfPoint SrcMtx;

 /// New variable
 MatOfPoint2f  NewMtx = new MatOfPoint2f( SrcMtx.toArray() );