[Interest] Quick Item visibility test / hit test... or synthesize press event
EXT Mitch Curtis
mitch.curtis at qt.io
Wed Jun 22 04:06:55 CEST 2022
There’s no public API for this specific task, but there have been suggestions for it:
https://bugreports.qt.io/browse/QTBUG-23745
https://bugreports.qt.io/browse/QTBUG-83647
From: Interest <interest-bounces at qt-project.org> on behalf of Federico Ferri <federico.ferri.it at gmail.com>
Date: Wednesday, 22 June 2022 at 05:26
To: Qt Project MailingList <interest at qt-project.org>
Subject: Re: [Interest] Quick Item visibility test / hit test... or synthesize press event
I have solved it more or less with this:
function traverseItemTreeWithClipping(item, pt, f, rootItem) {
rootItem = rootItem || item
var p = item.mapFromItem(rootItem, pt)
var inItemRect = p.x >= 0 && p.y >= 0 && p.x < item.width && p.y < item.height
if(item.clip && !inItemRect) return
f(item, p, inItemRect)
for(var i = 0; i < item.children.length; i++)
traverseItemTreeWithClipping(item.children[i], pt, f, rootItem)
}
function hitTest(rootItem, pt) {
var result = undefined
var z = -Infinity
traverseItemTreeWithClipping(rootItem, pt, (item, p, inItemRect) => {
if(item.visible && item.z >= z && inItemRect) {
result = item
z = item.z
}
})
return result
}
It only handles visibility and clipping. If there is a better way or I overlooked some QtQuick aspect, please let me know.
Cheers,
Federico Ferri
On Tue, Jun 21, 2022 at 8:54 PM Federico Ferri <federico.ferri.it at gmail.com<mailto:federico.ferri.it at gmail.com>> wrote:
Is it possible to find what is the topmost visible item given a pixel coordinate?
e.g. in this simplified example:
Rectangle {
x: 20; y: 20; width: 20; height: 20; color: 'red';
Rectangle {
x: 5; y: 10; width: 5; height: 5; color: 'green';
}
}
it would be the red Rectangle for coordinate (21,21), the green Rectangle for coordinate (26,32), and none for e.g. (15,15).
Alternatively, I'm happy to equip my Rectangles with a MouseArea {anchors.fill:parent} each. Is it possible then to synthesize mouse press events so to exploit Qt Quick's scenegraph/event processing magic?
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