MvvmCross Xamarin.Android FloatingActionButton toggle visibility

Question

This is my FloatingActionButton:

<android.support.design.widget.FloatingActionButton
        android:id="@+id/fab_add_retailer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:tint="@android:color/white"
        app:backgroundTint="@color/colorPrimary"
        app:srcCompat="@drawable/ic_add_black_24dp"
        local:MvxBind="Visibility IsAddButtonVisible, Converter=Visibility" />

Its visibility property is bound via MvvmCross to IsAddButtonVisible:

private bool _isAddButtonVisible = true;
public bool IsAddButtonVisible
{
    get
    {
        return _isAddButtonVisible;
    }
    set
    {
        _isAddButtonVisible = value;
        RaisePropertyChanged(() => IsAddButtonVisible);
    }
}

When I change the boolean value

ViewModel.IsAddButtonVisible = false;

...nothing happens. What am I doing wrong here? Thanks in advance!

Edit: when I bind using Visible, the toggling works

local:MvxBind="Visible IsAddButtonVisible"

but now I can't see any hide/show animations on the FloatingActionButton...

Answer 1

You would have to make use of a custom binding to use the method calls instead of the Visibility ViewStates changes.

---

Create the target binding that handles the executing the show and hide method calls based on the bool value you bind to.

public class FloatingActionButtonAnimateVisibleTargetBinding
    : MvxAndroidTargetBinding
{
    protected FloatingActionButton View => (FloatingActionButton)Target;

    public FloatingActionButtonAnimateVisibleTargetBinding(FloatingActionButton target)
        : base(target)
    {
    }

    public override Type TargetType => typeof(bool);

    protected override void SetValueImpl(object target, object value)
    {
        var isVisible = value.ConvertToBoolean();
        var floatingActionButton = target as FloatingActionButton;

        if (isVisible)
            floatingActionButton.Show();
        else
            floatingActionButton.Hide();
    }

}

Register the custom binding in your platform Setup.cs

protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
{
    base.FillTargetFactories(registry);

    registry.RegisterCustomBindingFactory<FloatingActionButton>(
        "VisibleAnim",
        button => new FloatingActionButtonAnimateVisibleTargetBinding(button));
}

Then you should be able to make use of the binding in your XML

local:MvxBind="VisibleAnim IsAddButtonVisible"