MapQuickItem loaded with Loader does not display - qt

Question

I am building a mapping program that eventually wants to display a different item on the map based on a value within the model. To facilitate this, I'm using Loader in my MapItemView delegate.
Unfortunately, when I tested this, the Loader method displayed nothing.
MapItemDelegate.qml
MapQuickItem {
id: waypoint
anchorPoint.x: image.width/2
anchorPoint.y: image.height/2
coordinate: task.waypoint //task extends QObject with members taskname and waypoint
sourceItem: Grid: {
columns: 1
rows:2
horizontalItemAlignment: Grid.AlignHCenter
Image {
id: image
source: "Waypoint.png"
height: 32
width: 32
}
Text {
id: text
text: task.taskname
}
}
}
main.qml
MapItemView {
id: taskview
model: tasklistmodel //Extends AbstractListModel to contain task objects
delegate: Component {
//Desired method, fails to display.
Loader {
source:"MapItemDelegate.qml"
// Will eventually be:
// source: task.typename+"MapItemDelegate.qml" to facilitate several types.
}
//Control method. Works fine, but does not meet my requirements.
MapItemDelegate {
//Nothing further needed.
}
}
}
How do I get MapItemView to actually display MapQuickItems loaded with Loader? Is there another method of dynamically loading delegates for display?

Answer 1

As it turns out, using a Loader within a delegate of MapItemView is not possible, as the API demands the Component contain a single mapping object. While Loader did load a mapping object, it is not in itself a mapping object, which caused the object to fail to display.
What I ended up doing is implementing a custom QSortFilterProxyModel that overrides filterAcceptsRow to filter tasklistmodel to match the task.typename property, then editing my MapItemView as follows:
MapItemView {
id:taskview
model: TaskListFilterModel { // custom extension of QSortFilterProxyModel
acceptType:"dothisthingtype"
sourceModel: tasklistmodel
}
delegate:MapItemDelegate {
}
}
With that, I can add a MapItemView for each type of task I plan to add in the future. While it's far less elegant and way more work than I had hoped to achieve with Loader, it does at least meet my requirements.