Drawing, rubber banding in a dialog (MFC)?

This is a discussion on Drawing, rubber banding in a dialog (MFC)? within the Windows Programming forums, part of the Platform Specific Boards category; I'm having a hard time figuring out how to rubber band a rectangle in a dialog. I've done this in ...

  1. #1
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    Drawing, rubber banding in a dialog (MFC)?

    I'm having a hard time figuring out how to rubber band a rectangle in a dialog. I've done this in a view by following some simple directions, and that took all of probably 3 minutes. The dialog seems to be entirely different as I no longer have OnDraw or the document/view architecture. The program is basically one large dialog with a 2D image rendered in the top right corner and the other buttons are for interacting with this image. What I want to do is rubber band a rectangle in this 2D image area on top of the image after it is rendered so that you may select and area in the 2D image. It sort of works, but it seems to kind of draw behind the 2D rendered image. When you try to select the area, you don't see anything during Lmousebuttondown and mousemove events until the lmousebuttonup event in which you see a white rectangle flash for a second and that's it. The selection itself works, you just cannot see what you are selecting, except in the separate and optional 3D view. I did not write this software to begin with, I just work on it part time (i'm a student). Thank you for any help you may be able to give.

  2. #2
    train spotter
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    Post some code...

    'Rubber banding', what do you mean?

    I draw a rectangle for selecting an area in an image. I have a 'frame' DC (just the image, a rectangle DC (transparent with rectangle drawn on it) and the screen DC.

    something like.....

    OnMouseMove
    clear rectangle DC
    draw new rectangle (watch conversion between screen coords and window coords)
    call a paint

    OnPaint
    if update rect includes image area
    draw image to screen DC
    if rectangle DC is not null
    draw rectangel to screen DC
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  3. #3
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    If you are using MFC, there is a CRectTracker class for this.

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