[Qt-interest] Screen coordinates inQGraphicsItem::hoverEnterEvent() ?

[Ross Bencina]

Hello Bertrand

Sorry, coming in a bit late on this. Interesting problem though...

I agree, as far as I know there is no obvious, simple direct way to do this.


bd.anon at free.fr:
> QGraphicsItem certainly knows about the Scene, but this is not a
> widget. True, from the scene, you can access the widget-derived view,
> displaying this scene, but how do I know which view to select when
> there are several of them displaying the same scene ?

I realise it's a bit of a hack, but this should work:

QGraphicsSceneHoverEvent::screenPos() will give you the global screen 
position.

QApplication::widgetAt() will give you the widget at that position. This 
should be the viewport of your graphics scene view

You could combine this with a search of QGraphicsScene::views() to find the 
correct view. Alternatively you could just search the views and see which 
one contains QGraphicsSceneHoverEvent::screenPos(). However this might have 
z-order problems whereas QApplication::widgetAt() will not.

Another option:

You can use QGraphicsSceneHoverEvent::screenPos()  with 
QDesktopWidget::screenGeometry() and QDesktopWidget::screen() to find a 
screen widget.



> I am certain there has to be a simple solution, but it escapes me. If
> you already solved this problem, a cut and paste of the relevant part
> of your QGraphicsItem::hoverEnterEvent() would be very helpful.

The solution I use only works when there is a single view. On top of that I 
have my own ToolTip implementation that takes a global rect to showText() 
but you get the idea...

QGraphicsView *view = patcherScene()->views().first();
QRectF anchorRect( toolTipAnchorRect() ); // rect of my graphics item i want 
to display a tooltip for

QRect screenRect(

view->mapToGlobal( view->mapFromScene( mapToScene( 
anchorRect.topLeft() ) ) ),

view->mapToGlobal( view->mapFromScene( mapToScene( 
anchorRect.bottomRight() ) + QPointF( 1.5, 1.5 ) ) ) );

AMToolTip::showText( toolTipText, 0, view, screenRect.adjusted( 0, -1, 0, 
2 ),

(direction() == INPUT_PORT) ? AMToolTip::AboveAlignedToLeft : 
AMToolTip::BelowAlignedToLeft );




Ross.