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Details

Type: Bug
Resolution: Done
Priority: P2: Important
Fix Version/s: 5.0.0
Affects Version/s: 5.0.0
Component/s: QML: Declarative and Javascript Engine
Labels:
None

Description

With the following code, press return to move the GridView content y to 120, then the space key to execute a move(1, 6, 3).

Observe the result is as attached in actual.png, where the item order is:

When instead it should be as attached in expected.png, i.e.

This is because the GridView in QSGItemView::applyModelChanges() receives the following changes:

[Removal] index 1, count 2
[Insertion] index 6, count 2
[Insertion] index 8, count 1

When in fact it should receive just

[Removal] index 1, count 3
[Insertion] index 6, count 3

The move is executed correctly if the content y is not changed to 120 before executing the move. The problem seems to arise from moving a mixture of visible and non-visible items.

import QtQuick 2.0

Item {
    width: 500; height: 500

    GridView {
        id: view2
        cellWidth: 80; cellHeight: 60
        width: 240; height: 320
        x: 100
        y: 100

        model: ListModel {
            id: model2
            Component.onCompleted: {
                for (var i=0; i<30; i++) {
                    append({'name': 'item ' + i, 'size': 20 })
                }
            }
        }
        delegate: Rectangle {
            width: 80; height: 60; border.width: 1
            Column {
                Text { text: name + " : " + index + " : " }
                Text { text: " " + parent.parent.x + ", " + parent.parent.y }
            }
        }

        highlight: Rectangle { width: 100; height: 100; color: "red"; opacity: 0.5; z:2 }

        focus: true
        Keys.onReturnPressed: view2.contentY = 120
        Keys.onSpacePressed: model2.move(1, 6, 3)
    }

    Rectangle {
        anchors.fill: view2
        color: "lightsteelblue"
        opacity: 0.7

    }

    Text { anchors.right: parent.right; text: "content y:" + view2.contentY + ", count: " + model2.count }
}