private ExpressionObserver CreateDataContextSubject(
IObservablePropertyBag target,
string path,
bool targetIsDataContext)
{
Contract.Requires <ArgumentNullException>(target != null);
var dataContextHost = targetIsDataContext ?
target.InheritanceParent as IObservablePropertyBag : target;
if (dataContextHost != null)
{
var result = new ExpressionObserver(
() => dataContextHost.GetValue(Control.DataContextProperty),
path);
dataContextHost.GetObservable(Control.DataContextProperty).Subscribe(x =>
result.UpdateRoot());
return(result);
}
else
{
throw new InvalidOperationException(
"Cannot bind to DataContext of object with no parent.");
}
}
public void Can_Replace_Root()
{
var first = new Class1 {
Foo = "foo"
};
var second = new Class1 {
Foo = "bar"
};
var root = first;
var target = new ExpressionObserver(() => root, "Foo");
var result = new List <object>();
var sub = target.Subscribe(x => result.Add(x));
root = second;
target.UpdateRoot();
root = null;
target.UpdateRoot();
Assert.Equal(new[] { "foo", "bar", PerspexProperty.UnsetValue }, result);
Assert.Equal(0, first.SubscriptionCount);
Assert.Equal(0, second.SubscriptionCount);
}
public void Empty_Expression_Should_Track_Root()
{
var data = new Class1 {
Foo = "foo"
};
var target = new ExpressionObserver(() => data.Foo, "");
var result = new List <object>();
target.Subscribe(x => result.Add(x));
data.Foo = "bar";
target.UpdateRoot();
Assert.Equal(new[] { "foo", "bar" }, result);
}
private ExpressionObserver CreateTemplatedParentExpressionSubject(IObservablePropertyBag target)
{
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
GetExpression());
if (target.GetValue(Control.TemplatedParentProperty) == null)
{
// TemplatedParent should only be set once, so only listen for the first non-null
// value.
target.GetObservable(Control.TemplatedParentProperty)
.Where(x => x != null)
.Take(1)
.Subscribe(x => result.UpdateRoot());
}
return(result);
}
public ExpressionObserver CreateExpressionObserver(
IObservablePropertyBag instance,
PerspexProperty property)
{
var dataContextHost = property != Control.DataContextProperty ?
instance :
instance.InheritanceParent as IObservablePropertyBag;
if (dataContextHost != null)
{
var result = new ExpressionObserver(
() => dataContextHost.GetValue(Control.DataContextProperty),
SourcePropertyPath);
dataContextHost.GetObservable(Control.DataContextProperty).Subscribe(x =>
result.UpdateRoot());
return(result);
}
return(null);
}
private ExpressionObserver CreateTemplatedParentSubject(
IObservablePropertyBag target,
string path)
{
Contract.Requires <ArgumentNullException>(target != null);
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
path);
if (target.GetValue(Control.TemplatedParentProperty) == null)
{
// TemplatedParent should only be set once, so only listen for the first non-null
// value.
target.GetObservable(Control.TemplatedParentProperty)
.Where(x => x != null)
.Take(1)
.Subscribe(x => result.UpdateRoot());
}
return(result);
}
public void Can_Replace_Root()
{
var first = new Class1 { Foo = "foo" };
var second = new Class1 { Foo = "bar" };
var root = first;
var target = new ExpressionObserver(() => root, "Foo");
var result = new List<object>();
var sub = target.Subscribe(x => result.Add(x));
root = second;
target.UpdateRoot();
root = null;
target.UpdateRoot();
Assert.Equal(new[] { "foo", "bar", PerspexProperty.UnsetValue }, result);
Assert.Equal(0, first.SubscriptionCount);
Assert.Equal(0, second.SubscriptionCount);
}
public void Empty_Expression_Should_Track_Root()
{
var data = new Class1 { Foo = "foo" };
var target = new ExpressionObserver(() => data.Foo, "");
var result = new List<object>();
target.Subscribe(x => result.Add(x));
data.Foo = "bar";
target.UpdateRoot();
Assert.Equal(new[] { "foo", "bar" }, result);
}
private ExpressionObserver CreateTemplatedParentSubject(
IObservablePropertyBag target,
string path)
{
Contract.Requires<ArgumentNullException>(target != null);
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
path);
if (target.GetValue(Control.TemplatedParentProperty) == null)
{
// TemplatedParent should only be set once, so only listen for the first non-null
// value.
target.GetObservable(Control.TemplatedParentProperty)
.Where(x => x != null)
.Take(1)
.Subscribe(x => result.UpdateRoot());
}
return result;
}
private ExpressionObserver CreateDataContextSubject(
IObservablePropertyBag target,
string path,
bool targetIsDataContext)
{
Contract.Requires<ArgumentNullException>(target != null);
if (!targetIsDataContext)
{
var result = new ExpressionObserver(
() => target.GetValue(Control.DataContextProperty),
path);
/// TODO: Instead of doing this, make the ExpressionObserver accept an "update"
/// observable as doing it this way can will cause a leak in Binding as this
/// observable is never unsubscribed.
target.GetObservable(Control.DataContextProperty).Subscribe(x =>
result.UpdateRoot());
return result;
}
else
{
return new ExpressionObserver(
target.GetObservable(Visual.VisualParentProperty)
.OfType<IObservablePropertyBag>()
.Select(x => x.GetObservable(Control.DataContextProperty))
.Switch(),
path);
}
}
private ExpressionObserver CreateTemplatedParentExpressionSubject(IObservablePropertyBag target)
{
var result = new ExpressionObserver(
() => target.GetValue(Control.TemplatedParentProperty),
GetExpression());
if (target.GetValue(Control.TemplatedParentProperty) == null)
{
// TemplatedParent should only be set once, so only listen for the first non-null
// value.
target.GetObservable(Control.TemplatedParentProperty)
.Where(x => x != null)
.Take(1)
.Subscribe(x => result.UpdateRoot());
}
return result;
}
private ExpressionObserver CreateDataContextExpressionSubject(
IObservablePropertyBag target,
bool targetIsDataContext)
{
var dataContextHost = targetIsDataContext ?
target.InheritanceParent as IObservablePropertyBag : target;
if (dataContextHost != null)
{
var result = new ExpressionObserver(
() => dataContextHost.GetValue(Control.DataContextProperty),
GetExpression());
dataContextHost.GetObservable(Control.DataContextProperty).Subscribe(x =>
result.UpdateRoot());
return result;
}
else
{
throw new InvalidOperationException(
"Cannot bind to DataContext of object with no parent.");
}
}
public ExpressionObserver CreateDataContextExpressionSubject(
IObservablePropertyBag instance,
PerspexProperty property)
{
var dataContextHost = property != Control.DataContextProperty ?
instance :
instance.InheritanceParent as IObservablePropertyBag;
if (dataContextHost != null)
{
var result = new ExpressionObserver(
() => dataContextHost.GetValue(Control.DataContextProperty),
GetExpression());
dataContextHost.GetObservable(Control.DataContextProperty).Subscribe(x =>
result.UpdateRoot());
return result;
}
return null;
}
