QGrapicsItems Interactions about qt

[therecipe]

Which functions do you need exactly?

[5k3105]

Hi!,

From your post in (#12) :

if you would want to be able to override virtual functions in QGraphicsLineItem, you would need to create a new QGraphicsLineItem with widgets.NewQGraphicsLineItem and then add it to the scene with scene.AddItem.

I'm trying to use the mouse hover:

hoverEnterEvent(QGraphicsSceneHoverEvent *)
hoverLeaveEvent(QGraphicsSceneHoverEvent *)
hoverMoveEvent(QGraphicsSceneHoverEvent *)

It's possible I'm not going about it right. So for each line or rectangle or circle I plot on the scene I want it to trigger it's hover events so I know which item it's over.

I tried this last week and it's didn't seem to work (I used AddRect, setAcceptHoverEvents and ConnectHoverEnterEvent I believe) then I remembered your post about that.

Thanks

[therecipe]

Hey

Yes, you need to create the items directly with NewQ* instead of add*.
(Because you want to override virtual functions and not signals)

You might want to also call the default virtual implementation (which always ends with *Default)

This works for me:

    var text = widgets.NewQGraphicsSimpleTextItem2("Hello 世界", nil)
    text.SetFont(gui.NewQFont2("Meiryo", 20, 2, false))
    text.SetAcceptHoverEvents(true)

    text.ConnectHoverEnterEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        text.SetText("entered")
        text.HoverEnterEventDefault(e)
    })

    text.ConnectHoverMoveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        text.SetText(fmt.Sprintf("moved %v %v", e.ScenePos().X(), e.ScenePos().Y()))
        text.HoverMoveEventDefault(e)
    })

    text.ConnectHoverLeaveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        text.SetText("leaved")
        text.HoverLeaveEventDefault(e)
    })

    scene.AddItem(text)

[5k3105]

I wonder what I was looking at. They are all implemented :/

Sorry! Thanks!

[5k3105]

With text.SetPos2(50, 50) this modification gives "moved 0 0" :

    text.ConnectHoverMoveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        var x, y = e.Pos().X(), e.Pos().Y()
        var i = scene.ItemAt3(x, y, nil)
        x, y = i.X(), i.Y()
        text.SetText(fmt.Sprintf("moved %v %v", x, y))
        text.HoverMoveEventDefault(e)
    })

Same with this:

    text.ConnectHoverMoveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        var x, y = e.Pos().X(), e.Pos().Y()
        var i = scene.ItemAt3(x, y, nil)
        var p = core.NewQPointF()
        p = i.ScenePos()
        x, y = p.X(), p.Y()
        text.SetText(fmt.Sprintf("moved %v %v", x, y))
        text.HoverMoveEventDefault(e)
    })

I would have thought x,y would be the coords of where the item is in the scene - 50 50.

My application draws rectangles on a grid. I am trying to retrieve the xy of the hovered item. Instead it always returns 0,0.

[5k3105]

It's strange that didn't work - but I found a better solution by subclassing QGaphicsItem. Thanks.

[therecipe]

Hey

This gives me moved 50 50

    text.SetPos2(50, 50)

    text.ConnectHoverMoveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        var x, y = e.ScenePos().X(), e.ScenePos().Y()
        var i = scene.ItemAt3(x, y, nil)
        x, y = i.X(), i.Y()

        text.SetText(fmt.Sprintf("moved %v %v", x, y))
        text.HoverMoveEventDefault(e)
    })

    text.ConnectHoverMoveEvent(func(e *widgets.QGraphicsSceneHoverEvent) {
        var x, y = e.ScenePos().X(), e.ScenePos().Y()
        var i = scene.ItemAt3(x, y, nil)
        var p = i.ScenePos()
        x, y = p.X(), p.Y()

        text.SetText(fmt.Sprintf("moved %v %v", x, y))
        text.HoverMoveEventDefault(e)
    })

I just needed to replace e.Pos() with e.ScenePos().

There are 3 different current positions you can get from the event e.Pos(), e.ScenePos() and e.ScreenPos() and you probably want to use e.ScenePos() most of the time.

Maybe take a look here: http://doc.qt.io/qt-5/qgraphicsscenehoverevent.html#pos