/// <summary>
/// Applies a binding subject to a property on an instance.
/// </summary>
/// <param name="target">The target instance.</param>
/// <param name="property">The target property.</param>
/// <param name="subject">The binding subject.</param>
internal void Bind(IPerspexObject target, PerspexProperty property, ISubject <object> subject)
{
var mode = Mode == BindingMode.Default ?
property.GetMetadata(target.GetType()).DefaultBindingMode : Mode;
switch (mode)
{
case BindingMode.Default:
case BindingMode.OneWay:
target.Bind(property, subject, Priority);
break;
case BindingMode.TwoWay:
throw new NotSupportedException("TwoWay MultiBinding not currently supported.");
case BindingMode.OneTime:
target.GetObservable(Control.DataContextProperty).Subscribe(dataContext =>
{
subject.Take(1).Subscribe(x => target.SetValue(property, x, Priority));
});
break;
case BindingMode.OneWayToSource:
target.GetObservable(property).Subscribe(subject);
break;
}
}
/// <inheritdoc/>
public InstancedBinding Initiate(
IPerspexObject target,
PerspexProperty targetProperty,
object anchor = null)
{
if (Name == "Red")
{
}
var host = (target as IControl) ?? (anchor as IControl);
var style = anchor as IStyle;
var resource = PerspexProperty.UnsetValue;
if (host != null)
{
resource = host.FindStyleResource(Name);
}
else if (style != null)
{
resource = style.FindResource(Name);
}
if (resource != PerspexProperty.UnsetValue)
{
return(new InstancedBinding(resource, Priority));
}
else
{
return(null);
}
}
/// <summary>
/// Gets an observable for a <see cref="PerspexProperty"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <typeparam name="T">The type of the property.</typeparam>
/// <param name="property">The property.</param>
/// <returns>
/// An observable which when subscribed pushes the old and new values of the property each
/// time it is changed.
/// </returns>
public static IObservable <Tuple <T, T> > GetObservableWithHistory <T>(
this IPerspexObject o,
PerspexProperty <T> property)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
return(new PerspexObservable <Tuple <T, T> >(
observer =>
{
EventHandler <PerspexPropertyChangedEventArgs> handler = (s, e) =>
{
if (e.Property == property)
{
observer.OnNext(Tuple.Create((T)e.OldValue, (T)e.NewValue));
}
};
o.PropertyChanged += handler;
return Disposable.Create(() =>
{
o.PropertyChanged -= handler;
});
},
GetDescription(o, property)));
}
/// <summary>
/// Gets an observable for a <see cref="PerspexProperty"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <param name="property">The property.</param>
/// <returns>An observable.</returns>
public static IObservable <object> GetObservable(this IPerspexObject o, PerspexProperty property)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
return(new PerspexObservable <object>(
observer =>
{
EventHandler <PerspexPropertyChangedEventArgs> handler = (s, e) =>
{
if (e.Property == property)
{
observer.OnNext(e.NewValue);
}
};
observer.OnNext(o.GetValue(property));
o.PropertyChanged += handler;
return Disposable.Create(() =>
{
o.PropertyChanged -= handler;
});
},
GetDescription(o, property)));
}
/// <summary>
/// Gets an observable for a <see cref="PerspexProperty"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <typeparam name="T">The property type.</typeparam>
/// <param name="property">The property.</param>
/// <returns>An observable.</returns>
public static IObservable <T> GetObservable <T>(this IPerspexObject o, PerspexProperty <T> property)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
return(o.GetObservable((PerspexProperty)property).Cast <T>());
}
/// <summary>
/// Binds a property to a subject according to a <see cref="BindingMode"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <param name="property">The property to bind.</param>
/// <param name="source">The binding source.</param>
/// <param name="mode">The binding mode.</param>
/// <param name="priority">The binding priority.</param>
/// <returns>An <see cref="IDisposable"/> which can be used to cancel the binding.</returns>
public static IDisposable Bind(
this IPerspexObject o,
PerspexProperty property,
ISubject <object> source,
BindingMode mode,
BindingPriority priority = BindingPriority.LocalValue)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
Contract.Requires <ArgumentNullException>(source != null);
switch (mode)
{
case BindingMode.Default:
case BindingMode.OneWay:
return(o.Bind(property, source, priority));
case BindingMode.TwoWay:
return(new CompositeDisposable(
o.Bind(property, source, priority),
o.GetObservable(property).Subscribe(source)));
case BindingMode.OneTime:
return(source.Take(1).Subscribe(x => o.SetValue(property, x, priority)));
case BindingMode.OneWayToSource:
return(o.GetObservable(property).Subscribe(source));
default:
throw new ArgumentException("Invalid binding mode.");
}
}
private ExpressionObserver CreateDataContexObserver(
IPerspexObject target,
string path,
bool targetIsDataContext)
{
Contract.Requires <ArgumentNullException>(target != null);
if (!targetIsDataContext)
{
var update = target.GetObservable(Control.DataContextProperty)
.Skip(1)
.Select(_ => Unit.Default);
var result = new ExpressionObserver(
() => target.GetValue(Control.DataContextProperty),
path,
update);
return(result);
}
else
{
return(new ExpressionObserver(
target.GetObservable(Visual.VisualParentProperty)
.OfType <IPerspexObject>()
.Select(x => x.GetObservable(Control.DataContextProperty))
.Switch(),
path));
}
}
/// <summary>
/// Applies the binding to a property on an instance.
/// </summary>
/// <param name="instance">The target instance.</param>
/// <param name="property">The target property.</param>
public void Bind(IPerspexObject instance, PerspexProperty property)
{
var subject = CreateSubject(instance, property);
if (subject != null)
{
Bind(instance, property, subject);
}
}
/// <summary>
/// Applies the binding to a property on an instance.
/// </summary>
/// <param name="instance">The target instance.</param>
/// <param name="property">The target property.</param>
public void Bind(IPerspexObject instance, PerspexProperty property)
{
var subject = CreateSubject(instance, property);
if (subject != null)
{
Bind(instance, property, subject);
}
}
/// <inheritdoc/>
void IDirectPropertyAccessor.SetValue(IPerspexObject instance, object value)
{
if (Setter == null)
{
throw new ArgumentException($"The property {Name} is readonly.");
}
Setter((TOwner)instance, (TValue)value);
}
/// <summary>
/// Gets a weak observable for a <see cref="PerspexProperty"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <param name="property">The property.</param>
/// <returns>An observable.</returns>
public static IObservable <object> GetWeakObservable(this IPerspexObject o, PerspexProperty property)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
return(new WeakPropertyChangedObservable(
new WeakReference <IPerspexObject>(o),
property,
GetDescription(o, property)));
}
/// <summary>
/// Animates a <see cref="PerspexProperty"/>.
/// </summary>
/// <typeparam name="T">The property type.</typeparam>
/// <param name="target">The target object.</param>
/// <param name="property">The target property.</param>
/// <param name="start">The value of the property at the start of the animation.</param>
/// <param name="finish">The value of the property at the end of the animation.</param>
/// <param name="easing">The easing function to use.</param>
/// <param name="duration">The duration of the animation.</param>
/// <returns>An <see cref="Animation"/> that can be used to track or stop the animation.</returns>
public static Animation <T> Property <T>(
IPerspexObject target,
PerspexProperty <T> property,
T start,
T finish,
IEasing <T> easing,
TimeSpan duration)
{
var o = GetTimer(duration).Select(progress => easing.Ease(progress, start, finish));
return(new Animation <T>(o, target.Bind(property, o, BindingPriority.Animation)));
}
/// <inheritdoc/>
public InstancedBinding Initiate(
IPerspexObject target,
PerspexProperty targetProperty,
object anchor = null)
{
Contract.Requires <ArgumentNullException>(target != null);
var pathInfo = ParsePath(Path);
ValidateState(pathInfo);
ExpressionObserver observer;
if (pathInfo.ElementName != null || ElementName != null)
{
observer = CreateElementObserver(
(target as IControl) ?? (anchor as IControl),
pathInfo.ElementName ?? ElementName,
pathInfo.Path);
}
else if (Source != null)
{
observer = CreateSourceObserver(Source, pathInfo.Path);
}
else if (RelativeSource == null || RelativeSource.Mode == RelativeSourceMode.DataContext)
{
observer = CreateDataContexObserver(
target,
pathInfo.Path,
targetProperty == Control.DataContextProperty,
anchor);
}
else if (RelativeSource.Mode == RelativeSourceMode.TemplatedParent)
{
observer = CreateTemplatedParentObserver(target, pathInfo.Path);
}
else
{
throw new NotSupportedException();
}
var subject = new ExpressionSubject(
observer,
targetProperty?.PropertyType ?? typeof(object),
Converter ?? DefaultValueConverter.Instance,
ConverterParameter,
FallbackValue,
Priority);
return(new InstancedBinding(subject, Mode, Priority));
}
/// <summary>
/// Creates a subject that can be used to get and set the value of the binding.
/// </summary>
/// <param name="target">The target instance.</param>
/// <param name="targetProperty">The target property.</param>
/// <returns>An <see cref="ISubject{Object}"/>.</returns>
public ISubject<object> CreateSubject(IPerspexObject target, PerspexProperty targetProperty)
{
if (Converter == null)
{
throw new NotSupportedException("MultiBinding without Converter not currently supported.");
}
var targetType = targetProperty?.PropertyType ?? typeof(object);
var result = new BehaviorSubject<object>(PerspexProperty.UnsetValue);
var children = Bindings.Select(x => x.CreateSubject(target, null));
var input = children.CombineLatest().Select(x => ConvertValue(x, targetType));
input.Subscribe(result);
return result;
}
/// <summary>
/// Called when the <see cref="DataContext"/> property begins and ends being notified.
/// </summary>
/// <param name="o">The object on which the DataContext is changing.</param>
/// <param name="notifying">Whether the notifcation is beginning or ending.</param>
private static void DataContextNotifying(IPerspexObject o, bool notifying)
{
var control = o as Control;
if (control != null)
{
control.IsDataContextChanging = notifying;
if (!notifying)
{
control.OnDataContextChanged();
}
}
}
/// <summary>
/// Creates a subject that can be used to get and set the value of the binding.
/// </summary>
/// <param name="target">The target instance.</param>
/// <param name="targetProperty">The target property.</param>
/// <returns>An <see cref="ISubject{Object}"/>.</returns>
public ISubject <object> CreateSubject(IPerspexObject target, PerspexProperty targetProperty)
{
if (Converter == null)
{
throw new NotSupportedException("MultiBinding without Converter not currently supported.");
}
var targetType = targetProperty?.PropertyType ?? typeof(object);
var result = new BehaviorSubject <object>(PerspexProperty.UnsetValue);
var children = Bindings.Select(x => x.CreateSubject(target, null));
var input = children.CombineLatest().Select(x => ConvertValue(x, targetType));
input.Subscribe(result);
return(result);
}
/// <summary>
/// Applies an <see cref="InstancedBinding"/> a property on an <see cref="IPerspexObject"/>.
/// </summary>
/// <param name="target">The target object.</param>
/// <param name="property">The property to bind.</param>
/// <param name="binding">The instanced binding.</param>
/// <param name="anchor">
/// An optional anchor from which to locate required context. When binding to objects that
/// are not in the logical tree, certain types of binding need an anchor into the tree in
/// order to locate named controls or resources. The <paramref name="anchor"/> parameter
/// can be used to provice this context.
/// </param>
/// <returns>An <see cref="IDisposable"/> which can be used to cancel the binding.</returns>
public static IDisposable Apply(
IPerspexObject target,
PerspexProperty property,
InstancedBinding binding,
object anchor)
{
Contract.Requires <ArgumentNullException>(target != null);
Contract.Requires <ArgumentNullException>(property != null);
Contract.Requires <ArgumentNullException>(binding != null);
var mode = binding.Mode;
if (mode == BindingMode.Default)
{
mode = property.GetMetadata(target.GetType()).DefaultBindingMode;
}
switch (mode)
{
case BindingMode.Default:
case BindingMode.OneWay:
return(target.Bind(property, binding.Observable ?? binding.Subject, binding.Priority));
case BindingMode.TwoWay:
return(new CompositeDisposable(
target.Bind(property, binding.Subject, binding.Priority),
target.GetObservable(property).Subscribe(binding.Subject)));
case BindingMode.OneTime:
var source = binding.Subject ?? binding.Observable;
if (source != null)
{
return(source.Take(1).Subscribe(x => target.SetValue(property, x, binding.Priority)));
}
else
{
target.SetValue(property, binding.Value, binding.Priority);
return(Disposable.Empty);
}
case BindingMode.OneWayToSource:
return(target.GetObservable(property).Subscribe(binding.Subject));
default:
throw new ArgumentException("Invalid binding mode.");
}
}
private ExpressionObserver CreateTemplatedParentObserver(
IPerspexObject target,
string path)
{
Contract.Requires <ArgumentNullException>(target != null);
var update = target.GetObservable(Control.TemplatedParentProperty)
.Skip(1)
.Select(_ => Unit.Default);
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
path,
update);
return(result);
}
/// <summary>
/// Creates a subject that can be used to get and set the value of the binding.
/// </summary>
/// <param name="target">The target instance.</param>
/// <param name="targetProperty">The target property. May be null.</param>
/// <returns>An <see cref="ISubject{Object}"/>.</returns>
public ISubject<object> CreateSubject(
IPerspexObject target,
PerspexProperty targetProperty)
{
Contract.Requires<ArgumentNullException>(target != null);
var pathInfo = ParsePath(Path);
ValidateState(pathInfo);
ExpressionObserver observer;
if (pathInfo.ElementName != null || ElementName != null)
{
observer = CreateElementObserver(
(IControl)target,
pathInfo.ElementName ?? ElementName,
pathInfo.Path);
}
else if (Source != null)
{
observer = CreateSourceObserver(Source, pathInfo.Path);
}
else if (RelativeSource == null || RelativeSource.Mode == RelativeSourceMode.DataContext)
{
observer = CreateDataContexObserver(
target,
pathInfo.Path,
targetProperty == Control.DataContextProperty);
}
else if (RelativeSource.Mode == RelativeSourceMode.TemplatedParent)
{
observer = CreateTemplatedParentObserver(target, pathInfo.Path);
}
else
{
throw new NotSupportedException();
}
return new ExpressionSubject(
observer,
targetProperty?.PropertyType ?? typeof(object),
Converter ?? DefaultValueConverter.Instance,
ConverterParameter,
FallbackValue);
}
/// <summary>
/// Gets a subject for a <see cref="PerspexProperty"/>.
/// </summary>
/// <typeparam name="T">The property type.</typeparam>
/// <param name="o">The object.</param>
/// <param name="property">The property.</param>
/// <param name="priority">
/// The priority with which binding values are written to the object.
/// </param>
/// <returns>
/// An <see cref="ISubject{T}"/> which can be used for two-way binding to/from the
/// property.
/// </returns>
public static ISubject <T> GetSubject <T>(
this IPerspexObject o,
PerspexProperty <T> property,
BindingPriority priority = BindingPriority.LocalValue)
{
// TODO: Subject.Create<T> is not yet in stable Rx : once it is, remove the
// AnonymousSubject classes from this file and use Subject.Create<T>.
var output = new Subject <T>();
var result = new AnonymousSubject <T>(
Observer.Create <T>(
x => output.OnNext(x),
e => output.OnError(e),
() => output.OnCompleted()),
o.GetObservable(property));
o.Bind(property, output, priority);
return(result);
}
/// <summary>
/// Binds a property on an <see cref="IPerspexObject"/> to an <see cref="IBinding"/>.
/// </summary>
/// <param name="target">The object.</param>
/// <param name="property">The property to bind.</param>
/// <param name="binding">The binding.</param>
/// <param name="anchor">
/// An optional anchor from which to locate required context. When binding to objects that
/// are not in the logical tree, certain types of binding need an anchor into the tree in
/// order to locate named controls or resources. The <paramref name="anchor"/> parameter
/// can be used to provice this context.
/// </param>
/// <returns>An <see cref="IDisposable"/> which can be used to cancel the binding.</returns>
public static IDisposable Bind(
this IPerspexObject target,
PerspexProperty property,
IBinding binding,
object anchor = null)
{
Contract.Requires <ArgumentNullException>(target != null);
Contract.Requires <ArgumentNullException>(property != null);
Contract.Requires <ArgumentNullException>(binding != null);
var result = binding.Initiate(target, property, anchor);
if (result != null)
{
return(BindingOperations.Apply(target, property, result, anchor));
}
else
{
return(Disposable.Empty);
}
}
private ExpressionObserver CreateDataContexObserver(
IPerspexObject target,
string path,
bool targetIsDataContext,
object anchor)
{
Contract.Requires <ArgumentNullException>(target != null);
if (!(target is IControl))
{
target = anchor as IControl;
if (target == null)
{
throw new InvalidOperationException("Cannot find a DataContext to bind to.");
}
}
if (!targetIsDataContext)
{
var update = target.GetObservable(Control.DataContextProperty)
.Skip(1)
.Select(_ => Unit.Default);
var result = new ExpressionObserver(
() => target.GetValue(Control.DataContextProperty),
path,
update);
return(result);
}
else
{
return(new ExpressionObserver(
target.GetObservable(Visual.VisualParentProperty)
.OfType <IPerspexObject>()
.Select(x => x.GetObservable(Control.DataContextProperty))
.Switch(),
path));
}
}
/// <summary>
/// Binds a property on an <see cref="IPerspexObject"/> to an <see cref="IBinding"/>.
/// </summary>
/// <param name="o">The object.</param>
/// <param name="property">The property to bind.</param>
/// <param name="binding">The binding.</param>
/// <returns>An <see cref="IDisposable"/> which can be used to cancel the binding.</returns>
public static IDisposable Bind(
this IPerspexObject o,
PerspexProperty property,
IBinding binding)
{
Contract.Requires <ArgumentNullException>(o != null);
Contract.Requires <ArgumentNullException>(property != null);
Contract.Requires <ArgumentNullException>(binding != null);
var mode = binding.Mode;
if (mode == BindingMode.Default)
{
mode = property.GetMetadata(o.GetType()).DefaultBindingMode;
}
return(o.Bind(
property,
binding.CreateSubject(o, property),
mode,
binding.Priority));
}
/// <inheritdoc/>
object IDirectPropertyAccessor.GetValue(IPerspexObject instance)
{
return(Getter((TOwner)instance));
}
private ExpressionObserver CreateTemplatedParentObserver(
IPerspexObject target,
string path)
{
Contract.Requires<ArgumentNullException>(target != null);
var update = target.GetObservable(Control.TemplatedParentProperty)
.Skip(1)
.Select(_ => Unit.Default);
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
path,
update);
return result;
}
private ExpressionObserver CreateDataContexObserver(
IPerspexObject target,
string path,
bool targetIsDataContext)
{
Contract.Requires<ArgumentNullException>(target != null);
if (!targetIsDataContext)
{
var update = target.GetObservable(Control.DataContextProperty)
.Skip(1)
.Select(_ => Unit.Default);
var result = new ExpressionObserver(
() => target.GetValue(Control.DataContextProperty),
path,
update);
return result;
}
else
{
return new ExpressionObserver(
target.GetObservable(Visual.VisualParentProperty)
.OfType<IPerspexObject>()
.Select(x => x.GetObservable(Control.DataContextProperty))
.Switch(),
path);
}
}
/// <summary>
/// Applies a binding subject to a property on an instance.
/// </summary>
/// <param name="target">The target instance.</param>
/// <param name="property">The target property.</param>
/// <param name="subject">The binding subject.</param>
internal void Bind(IPerspexObject target, PerspexProperty property, ISubject<object> subject)
{
var mode = Mode == BindingMode.Default ?
property.DefaultBindingMode : Mode;
switch (mode)
{
case BindingMode.Default:
case BindingMode.OneWay:
target.Bind(property, subject, Priority);
break;
case BindingMode.TwoWay:
throw new NotSupportedException("TwoWay MultiBinding not currently supported.");
case BindingMode.OneTime:
target.GetObservable(Control.DataContextProperty).Subscribe(dataContext =>
{
subject.Take(1).Subscribe(x => target.SetValue(property, x, Priority));
});
break;
case BindingMode.OneWayToSource:
target.GetObservable(property).Subscribe(subject);
break;
}
}
/// <summary>
/// Gets a description of a property that van be used in observables.
/// </summary>
/// <param name="o">The object.</param>
/// <param name="property">The property</param>
/// <returns>The description.</returns>
private static string GetDescription(IPerspexObject o, PerspexProperty property)
{
return($"{o.GetType().Name}.{property.Name}");
}
