Qt-interest Archive, August 2006
QGraphicsView -- background mouse events
Message 1 in thread
Hi
I'm implementing a direct-manipulation graph editor type thingy, and one of
the things I'd like to do is pick up mouse events which occur in the scene
when the mouse is not over any item. I've tried two approaches, both have
some shortcomings, I'm wondering if you can give any guidance on whether
there's a different way to do what I want. The approaches I've tried:
1) Create a special background QGraphicsItem which is at the back of the
z-order and collect all clicks from it. This works well except that I need
to work out how to resize it so that it is always big enough to collect all
clicks, but never so big that it causes the scroll bars to appear
unnecessarily (not sure how to handle this at all, what if there are
multiple views?).
2) Subclass QGraphicsScene and collect mouse events there. This works great
for mouse press and mouse release, but doesn't work at all for mouseMove
(mouseMove is only propogated to the scene if there is a mouse grabber item
(is this a bug?)).
Thanks!
Ross.
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