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  1. #1
    Join Date
    Oct 2021
    Posts
    2

    MFC CRectTracker

    Hi,

    I am trying to develop a MFC application that lets a user upload a photo and display it, and then the user will select a rectangular region of this photo and get its coordinates in pixel values.
    I am quite new to C++ (have mainly done C in the past) but I have managed to load and display the image, however I am a bit stuck on defining the region.

    After some research I found that the CRectTracker Class probably will be able to achieve what I need, but I cannot seem to understand how it works from the Microsoft documentation provided.
    As far as I can tell I need to use the CRectTracker::Track as the description says "Call this function to display the user interface for resizing the rectangle" but when I call it nothing happens (nothing appears on the application to suggest that I can resize any rectangle).

    This is what I got so far, any help would be greatly appreciated.
    Code:
    CRect rect2;
    CPoint p;
    CWnd* pWnd = GetDlgItem(IDC_PICTURE_CALIBRATION); //This is the ID of CStatic that is the photo displayed 
    pWnd->GetWindowRect(&rect2);
    ScreenToClient(&rect2);
    CRectTracker ROI = CRectTracker(rect2, CRectTracker::resizeOutside);
    pScreenDC = GetDC();
    //ROI.Draw(pScreenDC);
    ROI.Track(pWnd, GetCursorPos(&p), FALSE, NULL);
    ReleaseDC(pScreenDC);

  2. #2
    VictorN's Avatar
    VictorN is offline Super Moderator Power Poster
    Join Date
    Jan 2003
    Location
    Hanover Germany
    Posts
    20,222

    Re: MFC CRectTracker

    I never user this class and have no idea how and why should it be used.
    however, you could start with the Microsoft sample Tracker
    Victor Nijegorodov

  3. #3
    Join Date
    Oct 2021
    Posts
    2

    Re: MFC CRectTracker

    Thanks for the example.
    I have now managed to get a resizable rectangle on my application but I am facing another problem which is that the rectangle is behind the image so it can't be seen. Is there any way of moving the CRectTracker object to the front?

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