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Android MvxLinearLayout

Edit

Available from Android API 1, MvvmCross 3.

MvvmCross has a special implementation of Android’s LinearLayout, which works kind of like DataTemplate in XAML. This is useful when wanting to repeat a Android layout with MvvmCross bindings multiple times. This is very similar to MvxListView and MvxRecyclerView. However, without the memory management they provide, even though it uses the same MvxAdapter as MvxListView uses.

In order to use a MvxLinearLayout you need to provide a ItemTemplateId and a ItemsSource. Where the ItemTemplateId is the id of the Android layout you want to repeat and the ItemsSource being a collection of ViewModels you want to be bound to the layouts.

ItemTemplateId

This is the id of the Android layout you want to repeat. This will typically contain binding expressions that match the ViewModel contained in the ItemsSource you are binding.

Note: if ItemTemplateId is not set when binding, Android.Resource.Layout.SimpleListItem will be used and ToString() will be used from the ViewModel to bind this.

ItemsSource

This is the collection of ViewModels you want repeated in the MvxLinearLayout.

Misuse

Consider not misusing MvxLinearLayout for tasks MvxRecyclerView and MvxListView are better suited for. A good rule is, if the items you want to use MvxLinearLayout for do not all fit in the view bounds of the screen, then you should consider not using MvxLinearLayout as you can run into memory issues. These scenarios are handled better with proper Adapter Views.

Sample Use

This is a small sample that repeats buttons in a MvxLinearLayout.

ViewModel

ButtonViewModel

public class ButtonViewModel : MvxNotifyPropertyChanged
{
    private string _title;
    private ICommand _clickCommand;

    public string Title
    {
        get => _title;
        set => SetProperty(ref _title, value);
    }

    public MvxCommand ClickCommand
    {
        get => _clickCommand;
        set => SetProperty(ref _clickCommand, value);
    }
}

RepeatButtonViewModel

public class RepeatButtonViewModel : MvxViewModel
{
    public ObservableCollection<ButtonViewModel> Buttons
        = new ObservableCollection<ButtonViewModel>();

    public RepeatButtonViewModel()
    {
        Buttons.Add(new ButtonViewModel {
            Title = "Do stuff",
            ClickCommand = new MvxCommand(DoStuff)
        });

        Buttons.Add(new ButtonViewModel {
            Title = "Do other stuff",
            ClickCommand = new MvxCommand(DoOtherStuff)
        });
    }
}

View

item_button.axml

<?xml version="1.0" encoding="utf-8"?>
<Button
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    local:MvxBind="Text Title; Click ClickCommand"/>

activity_repeatbutton.axml

<?xml version="1.0" encoding="utf-8"?>
<MvxLinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    local:MvxItemTemplate="@layout/item_button"
    local:MvxBind="ItemsSource Buttons" />

RepeatButtonView

public class RepeatButtonView : MvxActivity<RepeatButtonViewModel>
{
    protected override void OnCreate(Bundle b)
    {
        base.OnCreat(b);

        SetContentView(Resource.Layout.activity_repeatbutton);
    }
}