UserControl Canvas.Left binding doesnt work - wpf

Question

So the problem is this. I need UserControl which will have set Canvas.Top and Canvas.Left but these properties are binded from the ViewModel. For simplicity let's have this code for the user control with no code behind:
<UserControl x:Class="BadBinding.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Canvas.Left="{Binding ElementName=slider, Path=Value}"
>
<Grid Width="100" Background="Red">
<Slider x:Name="slider" Minimum="100" Maximum="250" />
</Grid>
</UserControl>
And this code for the main window:
<Window x:Class="BadBinding.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525"
xmlns:local="clr-namespace:BadBinding"
>
<Canvas>
<local:MyUserControl />
</Canvas>
</Window>
I don't know why is binding not working. When you set Canvas.Left directly to some value everything is fine as well as writing content of the user control directly to the main window.

Answer 1

I think its because the UserControl is constructed befor being added to the Canvas and since Canvas.Left is an attached property it probably won't resolve correctly.
Try using a Reference binding.
<UserControl x:Class="BadBinding.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Canvas.Left="{Binding Source={x:Reference Name=slider}, Path=Value}"
>
<Grid Width="100" Background="Red">
<Slider x:Name="slider" Minimum="100" Maximum="250" />
</Grid>
</UserControl>
Note: you may get a compile warning, but it will still compile.
But I think the best option would be to create a property on your usercontrol to bind the value, this will also work.

Answer 2

I tried a lot with Bindings but it dint worked for me too.. so if you wanna go with EventHandler then the following workaround may help you..
Remove the Bindings and add an event handler to ValueChanged event
In your MyUserControl.xaml
<UserControl x:Class="BadBinding.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid Width="100" Background="Red">
<Slider x:Name="slider" Minimum="100" Maximum="250" ValueChanged="slider1_ValueChanged" />
</Grid>
</UserControl>
In your MyUserControl.xaml.cs
private void slider1_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
Canvas.SetLeft(this, slider1.Value);
}
I tried this and working for me if you find any problem then let me know..