The MvvmCross binding framework automatically adds one-way bind (from ViewModel to View) to all existing public Properties on any MonoDroid/Android View/widget.
If the public Property isn't of the correct type (e.g. it's some Android enumeration instead of a View), then you can use an IMvxValueConverter to do a conversion.
If you want to do 2-way binding, or there isn't a public Property for what you want to bind to, then you fairly easily do a custom binding. For an example of this, see the custom IsFavorite 2 way binding in the conference sample
This code adds a new bindable pseudo-property "IsFavorite" to every Android Button.
... this is initialised in Setup.cs using code like:
protected override void FillTargetFactories(MvvmCross.Binding.Interfaces.Bindings.Target.Construction.IMvxTargetBindingFactoryRegistry registry)
{
base.FillTargetFactories(registry);
registry.RegisterFactory(
new MvxCustomBindingFactory<Button>(
"IsFavorite",
(button) => new FavoritesButtonBinding(button)));
}
... and the binding code is:
public class FavoritesButtonBinding
: MvxBaseAndroidTargetBinding
{
private readonly Button _button;
private bool _currentValue;
public FavoritesButtonBinding(Button button)
{
_button = button;
_button.Click += ButtonOnClick;
}
private void ButtonOnClick(object sender, EventArgs eventArgs)
{
_currentValue = !_currentValue;
SetButtonBackground();
FireValueChanged(_currentValue);
}
public override void SetValue(object value)
{
var boolValue = (bool)value;
_currentValue = boolValue;
SetButtonBackground();
}
private void SetButtonBackground()
{
if (_currentValue)
{
_button.SetBackgroundResource(Resource.Drawable.star_gold_selector);
}
else
{
_button.SetBackgroundResource(Resource.Drawable.star_grey_selector);
}
}
protected override void Dispose(bool isDisposing)
{
if (isDisposing)
{
_button.Click -= ButtonOnClick;
}
base.Dispose(isDisposing);
}
public override Type TargetType
{
get { return typeof(bool); }
}
public override MvxBindingMode DefaultMode
{
get { return MvxBindingMode.TwoWay; }
}
}
