CODEWITHSUNDEEP
c#wpfbinding
wpfnoop
wpfnoop

Reputation: 188

Can't bind to DependencyProperty child of DependencyObject

I can't figure out how to bind my image:

<Image Source="{ Binding  Path=ViewModel.MainViewModel.ProcessedImage }" Name="image1"/>

to DependencyProperty ProcessedImage, which is child element of my custom class derived from DependencyObject:

class ViewModel : DependencyObject
{
    public static ViewModel MainViewModel { get; set; }

    [...]

    public BitmapImage ProcessedImage
    {
        get { return (BitmapImage)this.GetValue(ProcessedImageProperty); }
        set { this.SetValue(ProcessedImageProperty, value); }
    }
    public static readonly DependencyProperty ProcessedImageProperty = DependencyProperty.Register(
      "ProcessedImage", typeof(BitmapImage), typeof(ViewModel), new PropertyMetadata());
}

I hope You can help me out with this. I've tried different approaches but nothing seems to work.

Upvotes: 0

Views: 287

Answers (1)

Trev
Trev

Reputation: 48

How are you setting the data context? I copied your code and added another property - ProcessedImageName with a default value of "Hello World"

public static readonly DependencyProperty ProcessedImageNameProperty = DependencyProperty.Register(
        "ProcessedImageName", typeof(string), typeof(ViewModel), new PropertyMetadata("Hello World"));

    public string ProcessedImageName {
get { return (string)this.GetValue(ProcessedImageNameProperty); }
set { this.SetValue(ProcessedImageNameProperty, value); }}

The I set the data context as follows:

    public MainWindow()
    {
        InitializeComponent();
        ViewModel.MainViewModel = new ViewModel();
        DataContext = ViewModel.MainViewModel;
    }

The I set the binding path as:

<TextBlock Text="{Binding Path=ProcessedImageName }"/>

Personally, I wouldn't continue with the static MainViewModel property and would instead just new up a ViewModel instance as so

    public MainWindow()
    {
        InitializeComponent();
        DataContext = new ViewModel();
    }

The path to a property is relative to the data context so if a property is Class.PropertyName and the data context is Class then the binding path is just PropertyName.

Upvotes: 1

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