Opencv and drawing roi on mat

  • Hi...

    I try to draw a ROI (region of interest) on Mat with QMouseEvent and display it on QLabel.

    Got slot like this :
    void mDisplay::draw_ROI(int& r1,int& r2,QPoint& position, cv::Mat& matsROI)

    cv::Mat matfROI;
    cv::Rect rectang = cv::Rect(r1,r2,position.x()-r1,position.y()-r2);



    When mouseMoveEvent is triggered it emits signal with position of left button click (int& r1,int& r2) which works perfect,actual cursor position (QPoint& position) and matrix with picture (cv::Mat& matsRoi).All of that works great.
    The only problem is,that when I move cursor over QLabel, rectangle is drawn on same image which results in many rectangles.
    Shouldn't matfROI be copied again on every mouse move?

    I also declared int test = 0 just under declaration of matsROI and added to this slot
    int c = test;



    and it always shows 5 as expected,so why mat is not copied on each mouse move?

    PS. Tried to place this piece of code directly in mouseMoveEvent,but got same issue.

    Thanks in advance!

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