Question

I made a custom control ( it inherits from UserControl ) and my control contains 2 properties (dependency properties) “Start” and “End” , and a method that I named “BuildGraphic” and it’s this method that create the graphic of my control, the problem is when I change the value of a property I want to call this method to redraw the control, I tried with “OnRender” but it’s helpless.
PS : when I call “BuildGraphic” in the constructor, it works correctly.

Answer 1

Use a PropertyChangedCallback to call the method like so:

public static readonly DependencyProperty StartProperty = DependencyProperty.Register("Start", typeof(proptype), typeof(MyUserControl), new PropertyMetadata(DefaultValue, OnStartPropertyChanged));

private static void OnStartPropertyChanged(DependencyObject dependencyObject, 
           DependencyPropertyChangedEventArgs e) 
{  
    if (dependencyObject is MyUserControl)
    {
        ((MyUserControl)dependencyObject).BuildGraph();
    }
}