WPF PropertyPath on Custom control - wpf

Question

I have a problem, I create a control named Tile (like the Tile on Windows 10).
This tile simulate rotation 3D by using a projection class, like the projection class in Silverlight.
We have a base projection class like this :
abstract public class Projection
: FrameworkElement
{
static public readonly DependencyProperty RotationZProperty = DependencyProperty.Register(
nameof(RotationZ),
typeof(double),
typeof(Projection),
new UIPropertyMetadata(0.0, OnRotationChanged));
static public readonly DependencyProperty RotationYProperty = DependencyProperty.Register(
nameof(RotationY),
typeof(double),
typeof(Projection),
new UIPropertyMetadata(0.0, OnRotationChanged));
static public readonly DependencyProperty RotationXProperty = DependencyProperty.Register(
nameof(RotationX),
typeof(double),
typeof(Projection),
new UIPropertyMetadata(0.0, OnRotationChanged));
public double RotationZ
{
get { return this.GetValue<double>(RotationZProperty); }
set { SetValue(RotationZProperty, value); }
}
public double RotationY
{
get { return this.GetValue<double>(RotationYProperty); }
set { SetValue(RotationYProperty, value); }
}
public double RotationX
{
get { return this.GetValue<double>(RotationXProperty); }
set { SetValue(RotationXProperty, value); }
}
public FrameworkElement Child
{
get;
set;
}
static private void OnRotationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is Projection pl)
{
pl.OnRotationChanged();
}
}
private void OnRotationChanged()
{
// Some code
}}
After that, we have the PlaneProjectionClass :
[ContentProperty("Child")]
sealed public class PlaneProjection
: Projection
{
}
The Tile class use a dependency property of type Projection :
public class Tile
{
static public readonly DependencyProperty PlaneProjectionProperty = DependencyProperty.Register(
nameof(Projection),
typeof(Projection),
typeof(Tile),
new UIPropertyMetadata());
public Projection Projection
{
get { return (Projection)GetValue(PlaneProjectionProperty); }
private set { SetValue(PlaneProjectionProperty, value); }
}
override public void OnApplyTemplate()
{
Projection = GetTemplateChild("PART_Projection") as Projection;
}
}
So for the XAML, we have this in ControlTemplate :
<controls:PlaneProjection x:Name="PART_PlaneProjection">
<Border>
<Grid>
<!-- Some design -->
</Grid>
</Border>
</controls:PlaneProjection>
Now I would like to animate the planeprojection.
So I create the storyboard and animate the projection with rotationX :
static public void CreateAnimation(Tile tile)
{
Storyboard.SetTarget(anim, tile);
Storyboard.SetTargetProperty(doubleAnim, new PropertyPath("(Tile.Projection).(PlaneProjection.RotationX"));
}
But at debug, I have this error : Cannot resolve all references of the property on the path of the property '(Tile.Projection).(PlaneProjection.RotationX)
I don't understand the mistake :( Any ideas on using PropertyPath on custom control ?

Answer 1

The Projection property in class Tile does not follow the naming conventions for dependency properties.
It should e.g. look like this:
public static readonly DependencyProperty PlaneProjectionProperty =
DependencyProperty.Register(nameof(PlaneProjection), typeof(Projection), typeof(Tile));
public Projection PlaneProjection
{
get { return (Projection)GetValue(PlaneProjectionProperty); }
private set { SetValue(PlaneProjectionProperty, value); }
}
The property path would simply be this:
Storyboard.SetTargetProperty(anim, new PropertyPath("PlaneProjection.RotationX"));
You wouldn't even need a Storyboard. Just call
tile.PlaneProjection.BeginAnimation(Projection.RotationXProperty, anim);
As a note, a private setter does not make the dependency property read-only. See Read-Only Dependency Properties for details.