Image Quadrant Flipping in QT 5.0 running on Windows-7-64



  • I am having issues with trying to load image data from a buffer, modifying specified pixels via setPixel(),
    displaying it via a QGraphicsView and picking up mouse clicks from said view. For some reason, all my
    images seem to double flip exchange the image into diagonally flipped quadrants, i.e. the data that
    should be arranged as:

    @_ 0,0 0,1 0,2 0,3 | 0,4 0,5 0,6 0,7
    _ 1,0 1,1 1,2 1,3 | 1,4 1,5 1,6 1,7
    _ 2,0 2,1 2,2 2,3 | 2,4 2,5 2,6 2,7
    _ 3,0 3,1 3,2 3,3 | 3,4 3,5 3,6 3,7
    __----------------|----------------
    _ 4,0 4,1 4,2 4,3 | 4,4 4,5 4,6 4,7
    _ 5,0 5,1 5,2 5,3 | 5,4 5,5 5,6 5,7
    _ 6,0 6,1 6,2 6,3 | 6,4 6,5 6,6 6,7
    _ 7,0 7,1 7,2 7,3 | 7,4 7,5 7,6 7,7@

    is instead arranged, displayed and mouse position indicated as:

    @_ 4,4 4,5 4,6 4,7 | 4,0 4,1 4,2 4,3
    _ 5,4 5,5 5,6 5,7 | 5,0 5,1 5,2 5,3
    _ 6,4 6,5 6,6 6,7 | 6,0 6,1 6,2 6,3
    _ 7,4 7,5 7,6 7,7 | 7,0 7,1 7,2 7,3
    __----------------|----------------
    _ 0,4 0,5 0,6 0,7 | 0,0 0,1 0,2 0,3
    _ 1,4 1,5 1,6 1,7 | 1,0 1,1 1,2 1,3
    _ 2,4 2,5 2,6 2,7 | 2,0 2,1 2,2 2,3
    _ 3,4 3,5 3,6 3,7 | 3,0 3,1 3,2 3,3@

    So for example, if I try to set pixel (7,7) it will instead set (3,3), or
    (4,4) will set (0,0) and the opposite as well.

    I have had to write logical code to flip the pixels to the correct
    viewing location and to flip the mouse clicks as well. This happens
    regardless of the size of the image, always vertically and horizontally
    exchanging image halves. It makes for very confusing code and is quite
    prone to errors. Am I missing something? Is there a setting somewhere
    to account for this?

    I suspect that there is some setting that I am missing. I doubt that it
    is a bug, since images loaded from files don't seem to have this problem.

    Tanks

    Gary


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