Binding to multiple indexers

Question

I am trying to bind an indexed property with two indexers. The property looks like this

public Item this[int x, int y]
{
  get { return _items[x, y]; }
  set { _items[x, y] = value; }
}

According to http://msdn.microsoft.com/en-us/library/ms742451.aspx, it is possible to bind against indexed properties like that

<object Path="propertyName[index,index2...]" .../>

There is even an example:

<Rectangle Fill="{Binding ColorGrid[20,30].SolidColorBrushResult}" .../>

However when I try to access that property in XAML like that:

<Image Source="{Binding Items[0,0].Image}" />

I get an error in the designer:

The unnamed argument "0].Image" must appear before named arguments.

It seems to interpret 0].Image as the next argument. What am I missing?

Answer 1

The problem is the {Binding} markup extension - which has a delimiter which is ,.

To work around that you can use the following notation...

<TextBox Width="100" Height="100">
    <TextBox.Text>
        <Binding Path="MyIndexer[1,1]" />
    </TextBox.Text>
</TextBox>

Or use the 'escaped' , with \ - which is also in that link (but somehow they're getting over fact that their original notation doesn't work).

<TextBox Text="{Binding MyIndexer[2\,2]}" Width="100" Height="100" />  

Note that indexer, multi-dimentional array syntax is like this :)...

public string this[int x, int y]
{
    get { return _items[x][y]; }
    set { _items[x][y] = value; }
}

Answer 2

Windows Phone is not a WPF, it is mostly Silverlight, and Silverlight does not support Indexer:

• Only one-dimensional array indexing is supported.

You can try to fix this by:

a) Try to implement something like Items[0][0], so Items[0] will give you an array to which you again can apply indexer.

b) Try to implement this logic with IValueConverter.