/// <summary>
/// Causes the change event of the binding to occur only when the <see cref="Control.LostFocus"/> event is triggered.
/// </summary>
/// <remarks>
/// This is useful for text-based input controls such as the <see cref="NumericStepper"/> when a partial input can be invalid.
/// The binding will only be updated when the control has lost the input focus, where by default it will be updated for every
/// change while the user is updating the control.
/// </remarks>
/// <returns>A control binding that updates only when the control's input focus is lost.</returns>
public static BindableBinding <T, TValue> WhenLostFocus <T, TValue>(this BindableBinding <T, TValue> binding)
where T : Control
{
return(new BindableBinding <T, TValue>(
binding.DataItem,
c => binding.DataValue,
(c, v) => binding.DataValue = v,
addChangeEvent: (c, ev) => binding.DataItem.LostFocus += ev,
removeChangeEvent: (c, ev) => binding.DataItem.LostFocus -= ev
));
}
/// <summary>
/// Binds to an object's <see cref="IBindable.DataContext"/> using the specified <paramref name="dataContextBinding"/>.
/// </summary>
/// <remarks>
/// This creates a <see cref="DualBinding{TValue}"/> between a binding to the specified <paramref name="dataContextBinding"/> and this binding.
/// Since the data context changes, the binding passed for the data context binding is an indirect binding, in that it is reused.
/// The binding is added to the <see cref="IBindable.Bindings"/> collection.
/// </remarks>
/// <returns>A new dual binding that binds the <paramref name="dataContextBinding"/> to this control binding.</returns>
/// <param name="dataContextBinding">Binding to get/set values from/to the control's data context.</param>
/// <param name="mode">Dual binding mode.</param>
/// <param name="defaultControlValue">Default control value.</param>
/// <param name="defaultContextValue">Default context value.</param>
public DualBinding <TValue> BindDataContext(IndirectBinding <TValue> dataContextBinding, DualBindingMode mode = DualBindingMode.TwoWay, TValue defaultControlValue = default(TValue), TValue defaultContextValue = default(TValue))
{
var control = DataItem;
if (control == null)
{
throw new InvalidOperationException("Binding must be attached to a control");
}
var contextBinding = new BindableBinding <IBindable, object>(control, Binding.Delegate((IBindable w) => w.DataContext, null, (w, h) => w.DataContextChanged += h, (w, h) => w.DataContextChanged -= h));
var valueBinding = new ObjectBinding <object, TValue>(control.DataContext, dataContextBinding)
{
GettingNullValue = defaultControlValue,
SettingNullValue = defaultContextValue,
DataItem = contextBinding.DataValue
};
DualBinding <TValue> binding = Bind(sourceBinding: valueBinding, mode: mode);
contextBinding.DataValueChanged += delegate
{
((ObjectBinding <object, TValue>)binding.Source).DataItem = contextBinding.DataValue;
};
control.Bindings.Add(contextBinding);
return(binding);
}
/// <summary>
/// Adds a new binding to the control with a direct value binding
/// </summary>
/// <param name="bindable">Bindable object to add the binding to</param>
/// <param name="controlBinding">Binding to get/set the value from the control.</param>
/// <param name="valueBinding">Value binding to get/set the value from another source.</param>
/// <param name="mode">Mode of the binding</param>
public static DualBinding <T> Bind <T>(this IBindable bindable, IndirectBinding <T> controlBinding, DirectBinding <T> valueBinding, DualBindingMode mode = DualBindingMode.TwoWay)
{
var binding = new BindableBinding <IBindable, T>(bindable, controlBinding);
return(binding.Bind(sourceBinding: valueBinding, mode: mode));
}
/// <summary>
/// Adds a new binding from the control to its data context
/// </summary>
/// <param name="bindable">Bindable object to add the binding to</param>
/// <param name="controlBinding">Binding to get/set the value from the control.</param>
/// <param name="dataContextBinding">Binding to get/set the value from the <see cref="IBindable.DataContext"/>.</param>
/// <param name="mode">Mode of the binding.</param>
/// <param name="defaultControlValue">Default control value to set to the objectValue, if the value of the control property is null.</param>
/// <param name="defaultContextValue">Default context value to set to the control, if the objectValue or value of the objectBinding is null.</param>
public static DualBinding <T> BindDataContext <T>(this IBindable bindable, IndirectBinding <T> controlBinding, IndirectBinding <T> dataContextBinding, DualBindingMode mode = DualBindingMode.TwoWay, T defaultControlValue = default(T), T defaultContextValue = default(T))
{
var binding = new BindableBinding <IBindable, T>(bindable, controlBinding);
return(binding.BindDataContext(dataContextBinding, mode, defaultControlValue, defaultContextValue));
}
/// <summary>
/// Gets a binding that returns a <paramref name="defaultValue"/> if the specified <paramref name="binding"/> returns a null value.
/// </summary>
/// <returns>A new binding that returns a non-null value.</returns>
/// <param name="binding">Source of the binding to get the value.</param>
/// <param name="defaultValue">Default value to return instead of null.</param>
/// <typeparam name="T">The type of the bindable object.</typeparam>
/// <typeparam name="TValue">The value type.</typeparam>
public static BindableBinding <T, TValue> DefaultIfNull <T, TValue>(this BindableBinding <T, TValue> binding, TValue defaultValue)
where T : IBindable
where TValue : class
{
return(binding.Convert(c => c ?? defaultValue, c => c));
}
/// <summary>
/// Gets a binding that returns a <paramref name="defaultValue"/> if the specified <paramref name="binding"/> returns a null value.
/// </summary>
/// <returns>A new binding that returns a non-nullable value.</returns>
/// <param name="binding">Source of the binding to get the value.</param>
/// <param name="defaultValue">Default value, or null to use <c>default(TValue)</c>.</param>
/// <typeparam name="T">The type of the bindable object.</typeparam>
/// <typeparam name="TValue">The value type to convert from nullable to non-nullable.</typeparam>
public static BindableBinding <T, TValue> DefaultIfNull <T, TValue>(this BindableBinding <T, TValue?> binding, TValue?defaultValue = null)
where T : IBindable
where TValue : struct
{
return(binding.Convert(c => c ?? defaultValue ?? default(TValue), c => c));
}
/// <summary>
/// Gets a bindable binding with the inverse of the specified boolean value binding.
/// </summary>
/// <returns>A new binding to the inverse value.</returns>
/// <param name="binding">Binding to invert.</param>
/// <typeparam name="T">The type of the bindable object.</typeparam>
public static BindableBinding <T, bool> Inverse <T>(this BindableBinding <T, bool> binding)
where T : IBindable
{
return(binding.Convert(c => !c, c => !c));
}