CODEWITHSUNDEEP
xamarin.androidmvvmcross
jmmontero
jmmontero

Reputation: 169

Custom control without Adapter. Binding List

I created a Custom Control for monodroid. Following the tutorial N-20 CustomControl and this MvxListView because my control binding a IEnumerable. My control inherits to FrameLayout, then I don't have access to Adapter property from Parent Class.

When I assign the List binding property and call the RaisePropertyChanged event. Doesn't raise up. How can I do that?

Thanks in advance.

Edit to show code

Talk is cheap, I Show the code.

This is the header of custom control and the list of binding. 

    public class DrawingBoardControl : View
    {        

    private DrawingItems m_drawingItems;

    [MvxSetToNullAfterBinding]
    public DrawingItems CanvasItems
    {
        get
        {
            return m_drawingItems;
        }

        set
        {
            m_drawingItems = value;
            this.Update();
        }
    }
    ...

I use a class called "DrawingItems", there are

    public class DrawingItems : IEnumerable<IDrawingElement>
    {
    private List<IDrawingElement> myDrawingItems = new List<IDrawingElement>();

    public IEnumerator<IDrawingElement> GetEnumerator()
    {
        return myDrawingItems.GetEnumerator();
    }

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }

    public void Add(IDrawingElement element)
    {
        myDrawingItems.Add(element);
    }
  }

However, in other custom controls I use a IEnumerable and generic List and the problem persist.

When, I use RaisePropertyChanged in my ViewModel, the Items property don't raise.

Sorry for not include more information yesterday

Upvotes: 0

Views: 239

Answers (1)

Hugo Logmans
Hugo Logmans

Reputation: 2252

There are always some answers for uncomplete questions:

If you cannot access the Adapter of the parent, the parent has to set the context of the child. There are no more options. Make your custom control fully bindable by exposing the complete interfaces. The list has to provide the context for the list items.

Somehow a customcontrol binding to a IEnumerable feels very wrong. A custom control for displaying a list item, I can understand, but not for a list. But of course it can be done. But you end up setting references to the container class en setting the datacontext or viewmodel of each item.

But please provide more info if you want others to help.

UPDATE: Then I also update :) This provides some clues of the problem:

Don't assign a new list, but inherit the this from ObservableCollection, or manually call the raiseProperty with the correct parameters in the setter. I think it is by design assigning a new list will not call PropertyRaised.

As the 'App is King'-rule: in this case I notify the propertychanged myself. It might have something to do with the weak references problem (see the attribute on the ListItem property).

Upvotes: 2

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