QML Dynamic View Ordering Tutorial 4 - Sorting Items

Drag and drop isn't the only way items in a view can be re-ordered, using a DelegateModel it is also possible to sort items based on model data. To do that we extend our DelegateModel instance like this:

 
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    DelegateModel {
        id: visualModel
        property var lessThan: [
            function(left, right) { return left.name < right.name },
            function(left, right) { return left.type < right.type },
            function(left, right) { return left.age < right.age },
            function(left, right) {
                if (left.size == "Small")
                    return true
                else if (right.size == "Small")
                    return false
                else if (left.size == "Medium")
                    return true
                else
                    return false
            }
        ]

        property int sortOrder: orderSelector.selectedIndex
        onSortOrderChanged: items.setGroups(0, items.count, "unsorted")

        function insertPosition(lessThan, item) {
            var lower = 0
            var upper = items.count
            while (lower < upper) {
                var middle = Math.floor(lower + (upper - lower) / 2)
                var result = lessThan(item.model, items.get(middle).model);
                if (result) {
                    upper = middle
                }