Mvvmcross: [AndroidSupport] RecyclerView support for Footer/Header/Grouping (sections)

[thefex]

RecyclerView should have easy support to add footer/header and grouping onto lists.
Template of Footer/Header/Groups will be "somehow" selected by MvxTemplateSelector which I have implemented in past.

Taking task - gonna implement that.

[thefex]

Implemented feature + adjusted Android Support sample.
1. Support for RecyclerView Header
To add header to your MvxRecyclerView add in xml:
local:MvxHeaderLayoutId="@layout/recyclerviewexample_header"

To control header visibility if list is empty use:
local:MvxHidesHeaderIfEmpty="false" (true by default)

2. Support for RecyclerView Footer
To add footer to your MvxRecyclerView add in xml:
local:MvxFooterLayoutId="@layout/recyclerviewexample_footer"

To control header visibility if list is empty use:
local:MvxHidesFooterIfEmpty="false" (true by default)

3. Support for RecyclerView grouping
To use grouping with RecyclerView you have to:

• Your ViewModel list should implement IGrouping<TKey, TValue>
• You should add value converter class which inherit from MvxGroupedItemsConverter<TKey, TValue>
• Your MvxRecyclerView should look like:

        <MvxRecyclerView
            android:id="@+id/my_recycler_view"
            android:scrollbars="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            local:MvxItemTemplate="@layout/listitem_recyclerviewexample"
            local:MvxGroupSectionLayoutId="@layout/listitem_recyclerviewexample_groupheader"
            local:MvxBind="ItemsSource GroupedItems, Converter=StringGroupToMvxGroupedData; ItemClick ItemSelected" />

Please check sample project for more.

The only flaw of current grouping is that - it does not support Replace/Move ObservableCollection Changed events + there is no support for dynamic group child items change. I will probably create another issue for that when it's merged and implement this in future.

4. New commands
Additionaly MvxRecyclerViewcontains command properties like: - HeaderClickCommand, FooterClickCommand, GroupHeaderClickCommand.

5. Sample project
Android Support Droid sample project has been updated - please check that for more.

[thefex]

Can someone look at the latest commit?
I might need the new grouping model class to implement MvvmCross bindings for AdvancedRecyclerView bindings I have made for Xamarin.

[kjeremy]

I've looked at that latest commit and added some comments. I'm not sure what you mean by

I might need the new grouping model class to implement MvvmCross bindings for AdvancedRecyclerView bindings I have made for Xamarin.

Once those issues are addressed I'll check out the branch and poke around (it's a big change to just look at the diff!).

[thefex]

@kjeremy I have pushed new commit
@martijn00 I think it's now ready to merge

[Cybrosys]

Great work @thefex !

Is there a estimate of when the next release might happen and if that release will contain the grouping support? @martijn00

[Cheesebaron]

@Cybrosys soon. It will contain what is in develop currently.

[jonoommen]

Looks great @thefex! Can you please allow support for custom adapters and data binding for headers?

[MarcBruins]

@thefex Great work! Can you add some documentation about those changes? The above explanation is good! Its should be easy enough to do: https://www.mvvmcross.com/documentation/contribute/mvvmcross-docs-style-guide/mvvmcross-docs-style-guide.html

[alexshikov]

Any news on when grouping could be available?

[thefex]

It will be done through AdvancedRecyclerView library with MvvmCross bindings. It is more reliable and stable. Work still in progress, can't give accurate estimations (on my GitHub..)