Stone_Red/docs-desktop
1
0
Fork 0
mirror of https://github.com/Stone-Red-Code/docs-desktop.git synced 2026-09-08 16:06:07 +02:00
Code Issues Packages Projects Releases Wiki Activity

Replace various WPF include files with content (#1335)

Browse Source 
* net-current-v30plus-md.md

* net-current-v40plus-md.md

* tla2sharptla-ui-md.md

* tla2sharptla-uiautomation-md.md

* tla2sharptla-winclient-md.md

* tla2sharptla-xaml-md.md

* tlasharptla-ui-md.md

* tlasharptla-uiautomation-md.md

* tlasharptla-winclient-md.md

* tlasharptla-xaml-md.md

* fix warnings
This commit is contained in:
Andy (Steve) De George
2022-03-16 12:14:11 -04:00
committed by GitHub
parent dd0052ecec
commit be103da07e
353 changed files with 1339 additions and 1349 deletions
Download Patch File Download Diff File Expand all files Collapse all files
dotnet-desktop-guide/framework/wpf/advanced/property-change-events.md
+2 -2
View File
@@ -15,7 +15,7 @@ helpviewer_keywords:
ms.assetid: 0a7989df-9674-4cc1-bc50-5d8ef5d9c055
---
# Property Change Events
[!INCLUDE[TLA#tla_winclient](../../../includes/tlasharptla-winclient-md.md)] defines several events that are raised in response to a change in the value of a property. Often the property is a dependency property. The event itself is sometimes a routed event and is sometimes a standard common language runtime (CLR) event. The definition of the event varies depending on the scenario, because some property changes are more appropriately routed through an element tree, whereas other property changes are generally only of concern to the object where the property changed.
Windows Presentation Foundation (WPF) defines several events that are raised in response to a change in the value of a property. Often the property is a dependency property. The event itself is sometimes a routed event and is sometimes a standard common language runtime (CLR) event. The definition of the event varies depending on the scenario, because some property changes are more appropriately routed through an element tree, whereas other property changes are generally only of concern to the object where the property changed.
## Identifying a Property Change Event
Not all events that report a property change are explicitly identified as a property changed event, either by virtue of a signature pattern or a naming pattern. Generally, the description of the event in the SDK documentation indicates whether the event is directly tied to a property value change and provides cross-references between the property and event.
@@ -27,7 +27,7 @@ ms.assetid: 0a7989df-9674-4cc1-bc50-5d8ef5d9c055
Because you have an old value and a new value, it might be tempting to use this event handler as a validator for the property value. However, that is not the design intention of most property changed events. Generally, the values are provided so that you can act on those values in other logic areas of your code, but actually changing the values from within the event handler is not advisable, and may cause unintentional recursion depending on how your handler is implemented.
If your property is a custom dependency property, or if you are working with a derived class where you have defined the instantiation code, there is a much better mechanism for tracking property changes that is built in to the [!INCLUDE[TLA2#tla_winclient](../../../includes/tla2sharptla-winclient-md.md)] property system: the property system callbacks <xref:System.Windows.CoerceValueCallback> and <xref:System.Windows.PropertyChangedCallback>. For more details about how you can use the [!INCLUDE[TLA2#tla_winclient](../../../includes/tla2sharptla-winclient-md.md)] property system for validation and coercion, see [Dependency Property Callbacks and Validation](dependency-property-callbacks-and-validation.md) and [Custom Dependency Properties](custom-dependency-properties.md).
If your property is a custom dependency property, or if you are working with a derived class where you have defined the instantiation code, there is a much better mechanism for tracking property changes that is built in to the WPF property system: the property system callbacks <xref:System.Windows.CoerceValueCallback> and <xref:System.Windows.PropertyChangedCallback>. For more details about how you can use the WPF property system for validation and coercion, see [Dependency Property Callbacks and Validation](dependency-property-callbacks-and-validation.md) and [Custom Dependency Properties](custom-dependency-properties.md).
### DependencyPropertyChanged Events
Another pair of types that are part of a property changed event scenario is <xref:System.Windows.DependencyPropertyChangedEventArgs> and <xref:System.Windows.DependencyPropertyChangedEventHandler>. Events for these property changes are not routed; they are standard CLR events. <xref:System.Windows.DependencyPropertyChangedEventArgs> is an unusual event data reporting type because it does not derive from <xref:System.EventArgs>; <xref:System.Windows.DependencyPropertyChangedEventArgs> is a structure, not a class.