[Enhancement] Bindable Repeater control

[hartez]

Rationale

Forms does not currently contain a control which displays items from a bound items source in a non-scrollable container.

Implementation

Attached properties targeting Layout will be added to support an ItemsSource and ItemsTemplate. Setting these properties will add the templated items to the target layout.

public static class BindableLayout
{
    public static readonly BindableProperty ItemsSourceProperty =
        BindableProperty.Create("ItemsSource", typeof(IList), typeof(Layout), default(IList));

    public static readonly BindableProperty ItemTemplateProperty =
        BindableProperty.Create("ItemTemplate", typeof(DataTemplate), typeof(Layout);
}

The ItemTemplate is responsible for converting the objects in the ItemsSource into View objects.

Setting the ItemsSource will clear out any existing children and update the Children collection to match the source.

Backward Compatibility

These are new properties, so backward compatibility is likely not an issue.

Difficulty: Moderate

[StephaneDelcroix]

ItemsSource and ItemTemplate should be attached bindable properties, so it could be applied to Grid, StackLayout, Flex, ...

[hartez]

I have updated the proposed spec to reflect the attached property suggestions from GalaxiaGuy and StephaneDelcroix.

[hartez]

RE: https://github.com/xamarin/Xamarin.Forms/issues/1718#issuecomment-394780832

After careful consideration, CollectionView will not cover the scenario from this proposal: https://github.com/xamarin/Xamarin.Forms/issues/3172#issuecomment-424413234

So this proposal is back on the table.

[GalaxiaGuy]

@hartez Typo on the updated spec, both bindable properties are called ItemTemplate. :)

[hartez]

@hartez Typo on the updated spec, both bindable properties are called ItemTemplate. :)

D'oh! Thanks, fixed.