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; width: parent.width; height: 25; text: 'Empty'; Package.name: 'list' }
Text { id: gridDelegate; width: parent.width / 2; height: 50; text: 'Empty'; Package.name: 'grid' }
Rectangle {
id: wrapper
width: 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; width: 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
width: parent.width
model: visualModel.parts.list
}
GridView {
y: parent.height/2
height: parent.height/2
width: parent.width
cellWidth: width / 2
cellHeight: 50
model: visualModel.parts.grid
}