Adjust translation speed of QML DragHandler

Question

my question is about using a QML DragHandler to move a QML Item. I have successfully implemented position through dragging (when holding the Ctrl modifier) like so:

DragHandler {
    dragThreshold: 0
    acceptedModifiers: Qt.ControlModifier
}

Now I would like to add another handler that allows me to precisely position the element. Other software does this throught the use of the shift modifier. So what I want to do is move the element not by the pixel amount that the mouse moves, but an amount smaller than that. Ideally I would want to do something like this:

DragHandler {
    dragThreshold: 0
    acceptedModifiers: Qt.ShiftModifier

    onActiveTranslationChanged: {
        activeTranslation *= 0.5;
    }
}

Unfortunatelly activeTranslation is read-only and I don't see any other property I could use and I can't think of any other way to do it... Does anybody have an idea?

Thank you very much in advance!

Answer 1

Unfortunately Qt doesn't provide any way to change the drag speed AFAIK.

But this is a way to achieve it:

Rectangle
{
    id: theDraggableElement
    width: 100
    height: width
    color: "red"

    DragHandler
    {
        id: dragHandlerFast
        dragThreshold: 0
        acceptedModifiers: Qt.ControlModifier
        target: theDraggableElement
    }
}

Item
{
    id: invisibleItemForSlowDragging
    width: theDraggableElement.width
    height: theDraggableElement.height

    Binding { restoreMode: Binding.RestoreBinding; when: !dragHandlerSlow.active; target: invisibleItemForSlowDragging; property: "x"; value: theDraggableElement.x }
    Binding { restoreMode: Binding.RestoreBinding; when: !dragHandlerSlow.active; target: invisibleItemForSlowDragging; property: "y"; value: theDraggableElement.y }

    DragHandler
    {
        id: dragHandlerSlow
        dragThreshold: 0
        acceptedModifiers: Qt.ShiftModifier
        target: invisibleItemForSlowDragging

        onTranslationChanged:
        {
            theDraggableElement.x = invisibleItemForSlowDragging.x - dragHandlerSlow.translation.x / 2
            theDraggableElement.y = invisibleItemForSlowDragging.y - dragHandlerSlow.translation.y / 2
        }
    }
}

I have tested this with Qt 5.15.2.