In a document management program that I’m writing I’m displaying images in a QGraphicsView. The QGraphicsView supports a drag mode that allows a user to simply click and drag within the view to pan around, which works great when a large image is displayed and the user has zoomed in quite far.

Panning the image this way does mean that the user has to click back on the image and move the mouse again when the mouse reaches the end of the screen. I needed a way to implement mouse wrapping so that when the mouse reaches the end of the QGraphicsView during panning and the user is still holding down the left mouse button the mouse will jump to the opposite edge, giving a smooth continuous pan.

Here’s what I came up with…

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