select QPixmap area with mouse

[marcel]

You have to subclass QLabel and reimplement mousePressEvent, mouseMoveEvent and paintEvent.

In mousePressEvent: store the crop coordinates in a QRect or two QPoint's. The local coordinates are stored in the event.
When you receive the right click(you should implement some kind of click counting - a boolean flag, etc) you have the two local coordinates. Now you can crop the pixmap and set it in the label.

In mouseMoveEvent: after you have the coordinate for the left mouse click you can update the second coordinate with the current mouse position stored in the event.

In paintEvent: draw the crop rectangle specified by the left click position and right click position or current mouse position(if you didn't have a right click yet). Note that you first have to call QLabel:aintEvent and then draw your crop rectangle, because you want the label to be able to draw its initial contents.


As for storing the pixmaps, you can do that with a 1 QPixmap member, for the original image.