Dawid Sip wrote:
> Hi,
> im playing alot with GraphicsView these days and I came accross a
> following problem. I have a reimplemented QGraphicsView class where i
> interecept the keyboardkeys:
>
> protected void keyPressEvent(QKeyEvent event){
> event.accept();
> if(event.key()==Qt.Key.Key_Control.value())
> this.setDragMode(DragMode.ScrollHandDrag);
>
> super.keyPressEvent(event);
> }
>
> protected void keyReleaseEvent(QKeyEvent event){
> event.accept();
> if(event.key()==Qt.Key.Key_Control.value())
> this.setDragMode(DragMode.NoDrag);
>
> super.keyReleaseEvent(event);
> }
>
> I do this to achieve the following behaviour. When i press the ctrl key
> i want the DragMode to change to ScrollHandDrag. Then, when I press the
> left mouse key i can drag the viewport(scroll), when I'm done scrolling
> i release the left mouse button afterwhich i release the ctrl key. All
> works ok. But if I hit the following sequence of keys, the behavior will
> break. I press the ctrl key and then press the left mouse key, drag the
> view port and when I'm done I first release the ctrl key and then
> release the left mouse key. When I then want to repeat such scroll
> action the view port is drag as soon as I hit ctrl key, and not even
> tougch the mouse keys... What is wrong? Some ideas?
Hi Dawid,
This is caused by a bug in QGraphicsView. This will be fixed in Qt 4.5,
and in the meantime you can work around this by "faking" a mouseRelease
prior to unsetting the drag mode:
protected void keyReleaseEvent(QKeyEvent event){
event.accept();
if(event.key()==Qt.Key.Key_Control.value()) {
// Fake a mouse release...
QEvent e = new QMouseEvent(QEvent.Type.MouseButtonRelease,
new QPoint(0, 0),
Qt.MouseButton.LeftButton,
new Qt.MouseButtons(),
new Qt.KeyboardModifiers());
QApplication.sendEvent(viewport(), e);
this.setDragMode(DragMode.NoDrag);
}
super.keyReleaseEvent(event);
}
Hope this helps.
best regards,
Gunnar
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