How do you generally refer to the previous / next elements of a brother?
4 answers
Here we come !!
import QtQuick 2.0
Rectangle {
width: 800; height: 400
//if item is not parented, -1 is returned
function itemIndex(item) {
if (item.parent == null)
return -1
var siblings = item.parent.children
for (var i = 0; i < siblings.length; i++)
if (siblings[i] == item)
return i
return -1 //will never happen
}
//returns null, if the item is not parented, or is the first one
function previousItem(item) {
if (item.parent == null)
return null
var index = itemIndex(item)
return (index > 0)? item.parent.children[itemIndex(item) - 1]: null
}
//returns null, if item is not parented, or is the last one
function nextItem(item) {
if (item.parent == null)
return null
var index = itemIndex(item)
var siblings = item.parent.children
return (index < siblings.length - 1)? siblings[index + 1]: null
}
Rectangle {
width: 200; height: 200
color: "red"
}
Rectangle {
id: green
width: 200; height: 200
color: "green"
property Item previous: previousItem(green)
anchors.left: (previous != null)? previous.right: undefined
property Item next: nextItem(green)
anchors.right: (next != null)? next.left: undefined
}
Rectangle {
width: 200; height: 200
anchors.right: parent.right
color: "blue"
}
}
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Here is my code to handle this case. I usually put it in a top-level file, .qml
or even a common JavaScript module, so that I can use it everywhere without copying and pasting:
function indexOfChild (item, child) {
var ret = -1;
if (item && child && "children" in item) {
for (var idx = 0; ret < 0 && idx < item.children.length; idx++) {
if (item.children [idx] === child) {
ret = idx;
}
}
}
return ret;
}
function prevSibling (item, child) {
return (item.children [indexOfChild (item, child) -1] || null);
}
function nextSibling (item, child) {
return (item.children [indexOfChild (item, child) +1] || null);
}
And then I can just call any of these 3 methods ...
The only "drawback" is that you need to provide a parent in the arguments ...
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