Bindable layouts

[andreinitescu]

Description of Change

It allows any Layout<View> to generate its content (child views) by binding to an items source, with option to set item template or item template selector:

<StackLayout BindableLayout.ItemsSource="{Binding Items}" />

<StackLayout BindableLayout.ItemsSource="{Binding Items}"
             BindableLayout.ItemTemplate="{Binding MyItemTemplate}" />

<StackLayout BindableLayout.ItemsSource="{Binding Items}"
             BindableLayout.ItemTemplateSelector="{Binding MyItemTemplateSelector}" />

In the first example, where neither item template nor item template selector are set, every item is a Label. If both item template and selector are set, the item template is used. If Items property is set, it is ignored.

Issues Resolved

• fixes [Enhancement] Bindable Repeater control #1718

API Changes

Added static class BindableLayout with following attached properties to Layout<View>:

• public IEnumerable ItemsSource{ get; set; }
• public DataTemplate ItemTemplate { get; set; }
• public DataTemplateSelector ItemTemplateSelector { get; set; }
• private BindableLayoutController BindableLayoutController { get; set; }

Added private class BindableLayoutController which encapsulates updating layout children based on changes on the collection, item template or item template selector.

Platforms Affected

• Core/XAML (all platforms)

Testing Procedure

I added a gallery page (see screenshot below) which helps with testing all operations on a collection.

Before/After Screenshots

This change doesn't affect layout appearance, no matter the layout.
However I attached a screenshot which shows the gallery page:

The buttons should be self explanatory. "Replace" turns integers into chars to demonstrate replacing items in the observable collection. "Move" moves first item to last.

PR Checklist

• Has automated tests (See BindableLayoutTests unit tests)
• Rebased on top of the target branch at time of PR
• Changes adhere to coding standard

[andreinitescu]

@StephaneDelcroix All requested changes done

[rmarinho]

Hi @andreinitescu thanks for your contribution. We will need some unit tests.
UI Tests and a page on the gallery will also be great so we can try this out and test it.
You should also update the description related with the advance scneario as SetController is private now.
Screenshots will also be great.

Thanks

[StephaneDelcroix]

@rmarinho UITests aren't required, it can all be unit-tested

[andreinitescu]

@StephaneDelcroix @rmarinho @hartez

Updates:
✔️ Few fixes and naming per your suggestion (controller property name, event name, replaced ItemsSource return type from IList to IEnumerable)
✔️ Made few changes in the controller which reflect that it cannot be publicly set anymore (removed virtual methods from default controller)
✔️ Added gallery page (BindableLayoutGalleryPage)
✔️ Added unit tests (see BindableLayoutTests.cs)
✔️ Updated the ticket description and added screenshot with gallery page

@rmarinho Regarding your suggestion to update description with relevant advanced scenario for controller:
Since now setting controller is private per @StephaneDelcroix suggestion, advanced scenario is not applicable anymore.

[andreinitescu]

Squashed the commits

[andreinitescu]

@StephaneDelcroix @rmarinho @hartez Would appreciate your feedback, thanks!

[rmarinho]

Just tested, works fine for me. All my feedback was address. Good job.

[StephaneDelcroix]

I'm aware of the missed opportunity, we can consider opening this later