On Mon, 9 Feb 2015 11:39:06 +0100
Federico Buti <bacaro...@gmail.com> wrote:
> Hi all.
>
> Reading the documentation for mapToItem/mapFromItem functions I've
> understand that it is possibile to translate a point to/from the
> coordinate system of the item itself. In particular, given the
> signature:
>
> <itemName>.mapToItem(null, 0, 0)
>
>
> it is possibile to map the coordinate system origin of the item to the
> coordinate system of the top level window.
>
>
> This seems to work, as long as I don't use a Window, i.e. the
> following example gives different results (or correct ones which I
> cannot understand?):
>
>
> import QtQuick 2.4
>
> import QtQuick.Window 2.2
>
>
> Window {
>
> visible: true
>
> width: 600
>
> height: 600
>
> Rectangle {
>
> id: rec1
>
> x: 200
>
> y: 200
>
> width: 200
>
> height: 200
>
> color: "green"
>
> opacity: 0.5
>
> Component.onCompleted: {
>
> var coords = rec1.mapToItem(null, 0, 0)
>
> console.log("rec1: " + coords.x + "," + coords.y)
>
> }
>
> }
>
> Rectangle {
>
> id: rec2
>
> anchors.centerIn: parent
>
> width: 200
>
> height: 200
>
> color: "blue"
>
> opacity: 0.5
>
> Component.onCompleted: {
>
> var coords = rec2.mapToItem(null, 0, 0)
>
> console.log("rec2: " + coords.x + "," + coords.y)
>
> }
>
> }
>
> }
>
>
> The resulting coordinates are:
>
>
> qml: rec2: -100,-100
>
> qml: rec1: 200,200
>
>
> whereas I expected both rectangles to be at (200, 200). Window is not
> an Item, I know. Is this behaviour correct and I'm missing something
> trivial? Can the coordinates be traslated as expected?
>
>
> Thanks in advance,
>
> F.
Hello,
I noticed that you use an anchor for rect2. And for what I see, the (x,
y) of your Rectangle have not been yet setted by the layout management
when you pass through the onCompleted handler. If you listen on
on[XY]Changed, you will see that rect2 are first set to (-100, -100)
then position at (200, 200), giving you the expected result.
Hope that helps a bit,
Jean-Benoît
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