From MSDN: UnsetValue is a sentinel value that is used for scenarios where the WPF property system is unable to determine a requested DependencyProperty value. UnsetValue is used rather than null reference (Nothing in Visual Basic), because null reference could be a valid property value, as well as a valid (and frequently used) DefaultValue. Which … Read more
There are a few approaches: 1. The dependency property While you using the dependency property it makes the most sense in elements-classes that have a visual appearance (UIElements). Pros: WPF do the logic stuff for you Some mechanism like animation use only dependency property ‘Fits’ ViewModel style Cons: You need to derive form DependencyObject A … Read more
Here is how you can set your attached property in a style <Style x:Key=”ToolBarButtonStyle” TargetType=”Button”> <Setter Property=”PrismExt:ImgSourceAttachable.ImgSource” Value=”./Images/New.png”/> <!–…–> </Style> When binding to attached properties then the Path should be within parentheses so try to use RelativeSource Binding with TemplatedParent instead <Setter Property=”Template”> <Setter.Value> <ControlTemplate TargetType=”Button”> <Image x:Name=”toolbarImage” Source=”{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(PrismExt:ImgSourceAttachable.ImgSource)}” Width=”48″ Height=”48″> </Image> … Read more
Dependency properties and standard properties are quite different. The key features delivered by dependency properties are support for binding and animation. If you want to assign a value to a property using a Binding or template binding that property needs to be a dependency property. When animating a property the a dependency property can track … Read more
This helped me understand the reasoning: The main difference is, that the value of a normal .NET property is read directly from a private member in your class, whereas the value of a DependencyProperty is resolved dynamically when calling the GetValue() method that is inherited from DependencyObject. When you set a value of a dependency … Read more
I assume you meant DependencyProperty.Register and DependencyProperty.RegisterAttached. DependencyProperty.Register is used to register normal DependencyProperty. You can see those as just regular properties, with the added twist that they can take part in WPF’s DataBinding, animations etc. In fact, they are exposed as normal property (with the get and set accessors) on top of the untyped … Read more
The WPF binding engine calls GetValue and SetValue directly (bypassing the property setters and getters). You need the property to be there so it can be supported in the XAML markup (and compile correctly).
Override them like Michael Suggests above and to prevent folks from using the overridden (sp?) methods, mark them as obsolete: [Obsolete(“These are not supported in this class.”, true)] public override void dontcallmeanymore() { } If the second parm is set to true, a compiler error will be generated if anyone tries to call that method … Read more
I sometimes get this problem when I try to manually edit projects/solutions generated by our CMake system. I solve it manually: Open the dependent .vcproj file in your favorite text editor. Find <ProjectReference> tag corresponding to the dependency you want to remove (the include attribute of the tag will contain the name of the dependency … Read more
The MSDN link you provided says it quite well: This method is used by a component that programmatically sets the value of one of its own properties without disabling an application’s declared use of the property. The SetCurrentValue method changes the effective value of the property, but existing triggers, data bindings, and styles will continue … Read more