qml package 的使用

什么时候使用这个。就是多个view使用同一个deleagte的时候。

The Package class is used in conjunction with VisualDataModel to enable delegates with a shared context to be provided to multiple views.

Any item within a Package may be assigned a name via the Package.name attached property.

The example below creates a Package containing two named items; list and grid. The third item in the package (the Rectangle) is parented to whichever delegate it should appear in. This allows an item to move between views.

Package {
Text { id: listDelegate; parent.width; height: 25; text: 'Empty'; Package.name: 'list' }
Text { id: gridDelegate; parent.width / 2; height: 50; text: 'Empty'; Package.name: 'grid' }

Rectangle {
    id: wrapper
     parent.width; height: 25
    color: 'lightsteelblue'

    Text { text: display; anchors.centerIn: parent }
    state: root.upTo > index ? 'inGrid' : 'inList'
    states: [
        State {
            name: 'inList'
            ParentChange { target: wrapper; parent: listDelegate }
        },
        State {
            name: 'inGrid'
            ParentChange {
                target: wrapper; parent: gridDelegate
                x: 0; y: 0;  gridDelegate.width; height: gridDelegate.height
            }
        }
    ]

    transitions: [
        Transition {
            ParentAnimation {
                NumberAnimation { properties: 'x,y,width,height'; duration: 300 }
            }
        }
    ]
}

}
These named items are used as the delegates by the two views who reference the special VisualDataModel::parts property to select a model which provides the chosen delegate.

DelegateModel {
id: visualModel
delegate: Delegate {}
model: myModel
}

ListView {
id: lv
height: parent.height/2
parent.width

model: visualModel.parts.list

}
GridView {
y: parent.height/2
height: parent.height/2
parent.width
cellWidth: width / 2
cellHeight: 50
model: visualModel.parts.grid
}