Using MouseWheel for zoom: too many wheel events

maxwell31

Hi,

I have my custom plot, into which I want to zoom using the mouse wheel. My problem is, that when I scroll the wheel fast, I do not get one wheel event with a big angleDelta.y but several wheel events with the same angleDelta.y. This is problematic for me, because the mouseX position sets the center of the zoom. Thus if the wheel is scrolled fast, also the center is moving. Do you have a suggestion how I could improve this?

maxwell31

Ok, I have a solution using a timer:

MouseArea {
        id: zoomArea
        anchors.fill: parent
        acceptedButtons: Qt.LeftButton
        hoverEnabled: true

        property double zoomX: 0 // used as zoom position for wheel scrolling
        property double zoomY: 0 // used as zoom position for wheel scrolling
        Timer{
            id: zoomPosDelay
            running: false
            repeat: false
            interval: 500
        }
        onWheel: {
            if(zoomPosDelay.running==false) {
                zoomX = plot.xPixToData(mouseX)
                zoomY = plot.yPixToData(mouseY)
            }
            zoomPosDelay.start()

            if(wheel.angleDelta.y>0) {
                plot.setViewZoomWheel(zoomX,zoomY,1.2)

But my zoom does not feel natural yet. The problem is, that center the plot around the mouse position before the wheel event, which results in a big jump (translation) of the area. What is the standard way to deal with this e.g. in maps?