mirror of
https://github.com/Stone-Red-Code/docs-desktop.git
synced 2026-09-04 00:56:03 +02:00
Content update - XAML loading and dependency properties (user story 1878471) (#1257)
* Add article, toc, and redirects * Add info on use of a callback to run custom logic and resolve merge conflicts
This commit is contained in:
Tris Shores
@@ -588,6 +588,14 @@
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||||
{
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||||
"source_path": "dotnet-desktop-guide/framework/wpf/properties/safe-constructor-patterns-for-dependencyobjects.md",
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"redirect_url": "/dotnet/desktop/wpf/advanced/safe-constructor-patterns-for-dependencyobjects?view=netframeworkdesktop-4.8"
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},
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{
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"source_path": "dotnet-desktop-guide/net/wpf/advanced/xaml-loading-and-dependency-properties.md",
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"redirect_url": "/dotnet/desktop/wpf/properties/xaml-loading-and-dependency-properties?view=netdesktop-6.0"
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},
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{
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"source_path": "dotnet-desktop-guide/framework/wpf/properties/xaml-loading-and-dependency-properties.md",
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"redirect_url": "/dotnet/desktop/wpf/advanced/xaml-loading-and-dependency-properties?view=netframeworkdesktop-4.8"
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}
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]
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}
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+17
-6
@@ -1,8 +1,6 @@
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using System;
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using System.Diagnostics;
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using System.Windows;
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using System.Windows.Media;
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using System.Windows.Media.Imaging;
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using System.Windows.Shapes;
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namespace CodeSampleCsharp
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{
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@@ -11,6 +9,19 @@ namespace CodeSampleCsharp
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/// </summary>
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public partial class MainWindow : Window
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{
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public MainWindow()
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{
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InitializeComponent();
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// Test code.
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Aquarium aquarium = new();
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aquarium.AquariumGraphic = new Uri("http://www.contoso.com/aquarium-graphic-new.jpg");
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Debug.WriteLine($"Aquarium graphic: {aquarium.AquariumGraphic}");
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// Output:
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// OnUriChanged: http://www.contoso.com/aquarium-graphic-new.jpg
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// Aquarium graphic: http://www.contoso.com/aquarium-graphic-new.jpg
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}
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}
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public class Aquarium : DependencyObject
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@@ -32,7 +43,7 @@ namespace CodeSampleCsharp
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);
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//</RegisterDependencyProperty>
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// Declare a read-write property.
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// Declare a read-write property wrapper.
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public Uri AquariumGraphic
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{
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get => (Uri)GetValue(AquariumGraphicProperty);
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@@ -42,8 +53,8 @@ namespace CodeSampleCsharp
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private static void OnUriChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
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{
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Shape shape = (Shape)dependencyObject;
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shape.Fill = new ImageBrush(new BitmapImage((Uri)e.NewValue));
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Uri value = (Uri)dependencyObject.GetValue(AquariumGraphicProperty);
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Debug.WriteLine($"OnUriChanged: {value}");
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}
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}
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}
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+13
-3
@@ -8,7 +8,17 @@
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Public Sub New()
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InitializeComponent()
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' Test code.
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Dim aquarium As New Aquarium With {
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.AquariumGraphic = New Uri("http://www.contoso.com/aquarium-graphic-new.jpg")
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}
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Debug.WriteLine($"Aquarium graphic: {aquarium.AquariumGraphic}")
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End Sub
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' Output:
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' OnUriChanged http://www.contoso.com/aquarium-graphic-new.jpg
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' Aquarium graphic: http://www.contoso.com/aquarium-graphic-new.jpg
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End Class
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Public Class Aquarium
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@@ -30,7 +40,7 @@
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propertyChangedCallback:=New PropertyChangedCallback(AddressOf OnUriChanged)))
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'</RegisterDependencyProperty>
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' Declare a read-write property.
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' Declare a read-write property wrapper.
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Public Property AquariumGraphic As Uri
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Get
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Return CType(GetValue(AquariumGraphicProperty), Uri)
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@@ -42,8 +52,8 @@
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'</RegisterDependencyPropertyWithWrapper>
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Private Shared Sub OnUriChanged(dependencyObject As DependencyObject, e As DependencyPropertyChangedEventArgs)
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Dim shape As Shape = CType(dependencyObject, Shape)
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shape.Fill = New ImageBrush(New BitmapImage(CType(e.NewValue, Uri)))
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Dim value As Uri = CType(dependencyObject.GetValue(AquariumGraphicProperty), Uri)
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Debug.WriteLine($"OnUriChanged: {value}")
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End Sub
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End Class
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+17
@@ -0,0 +1,17 @@
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using System;
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using System.Collections.Generic;
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using System.Configuration;
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using System.Data;
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using System.Linq;
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using System.Threading.Tasks;
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using System.Windows;
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namespace CodeSampleCsharp
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{
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/// <summary>
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/// Interaction logic for App.xaml
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/// </summary>
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public partial class App : Application
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{
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}
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}
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+10
@@ -0,0 +1,10 @@
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using System.Windows;
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[assembly: ThemeInfo(
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ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
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//(used if a resource is not found in the page,
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// or application resource dictionaries)
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ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
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//(used if a resource is not found in the page,
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// app, or any theme specific resource dictionaries)
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)]
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+25
@@ -0,0 +1,25 @@
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>WinExe</OutputType>
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<TargetFramework>net6.0-windows</TargetFramework>
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<UseWPF>true</UseWPF>
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<NeutralLanguage>en-US</NeutralLanguage>
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</PropertyGroup>
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<ItemGroup>
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<Compile Update="Properties\Resources.Designer.cs">
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<DesignTime>True</DesignTime>
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<AutoGen>True</AutoGen>
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<DependentUpon>Resources.resx</DependentUpon>
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</Compile>
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</ItemGroup>
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<ItemGroup>
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<EmbeddedResource Update="Properties\Resources.resx">
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<Generator>ResXFileCodeGenerator</Generator>
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<LastGenOutput>Resources.Designer.cs</LastGenOutput>
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</EmbeddedResource>
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</ItemGroup>
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</Project>
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+5
@@ -0,0 +1,5 @@
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<Window x:Class="CodeSampleCsharp.MainWindow"
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xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
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xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:CodeSampleCsharp"
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Title="XAML loading and dependency properties" Height="100" Width="400">
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</Window>
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+61
@@ -0,0 +1,61 @@
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using System;
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using System.Diagnostics;
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using System.Windows;
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namespace CodeSampleCsharp
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{
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/// <summary>
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/// Interaction logic for MainWindow.xaml.
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/// </summary>
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public partial class MainWindow : Window
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||||
{
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public MainWindow()
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{
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InitializeComponent();
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// Test code.
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Aquarium aquarium = new();
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aquarium.AquariumGraphic = new Uri("http://www.contoso.com/aquarium-graphic-new.jpg");
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Debug.WriteLine($"Aquarium graphic: {aquarium.AquariumGraphic}");
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// Output:
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// OnUriChanged: http://www.contoso.com/aquarium-graphic-new.jpg
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// Aquarium graphic: http://www.contoso.com/aquarium-graphic-new.jpg
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}
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}
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public class Aquarium : DependencyObject
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{
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//<DependencyPropertyWithWrapper>
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// Register a dependency property with the specified property name,
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// property type, owner type, and property metadata. Store the dependency
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// property identifier as a public static readonly member of the class.
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public static readonly DependencyProperty AquariumGraphicProperty =
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DependencyProperty.Register(
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name: "AquariumGraphic",
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propertyType: typeof(Uri),
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ownerType: typeof(Aquarium),
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typeMetadata: new FrameworkPropertyMetadata(
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defaultValue: new Uri("http://www.contoso.com/aquarium-graphic.jpg"),
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flags: FrameworkPropertyMetadataOptions.AffectsRender,
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propertyChangedCallback: new PropertyChangedCallback(OnUriChanged))
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);
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// Property wrapper with get & set accessors.
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public Uri AquariumGraphic
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{
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get => (Uri)GetValue(AquariumGraphicProperty);
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set => SetValue(AquariumGraphicProperty, value);
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}
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// Property-changed callback.
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private static void OnUriChanged(DependencyObject dependencyObject,
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DependencyPropertyChangedEventArgs e)
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{
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// Some custom logic that runs on effective property value change.
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Uri newValue = (Uri)dependencyObject.GetValue(AquariumGraphicProperty);
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Debug.WriteLine($"OnUriChanged: {newValue}");
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}
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//</DependencyPropertyWithWrapper>
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}
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}
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+63
@@ -0,0 +1,63 @@
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//------------------------------------------------------------------------------
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||||
// <auto-generated>
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||||
// This code was generated by a tool.
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||||
// Runtime Version:4.0.30319.42000
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||||
//
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||||
// Changes to this file may cause incorrect behavior and will be lost if
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||||
// the code is regenerated.
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||||
// </auto-generated>
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//------------------------------------------------------------------------------
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namespace CodeSampleCsharp.Properties {
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||||
using System;
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||||
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||||
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||||
/// <summary>
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||||
/// A strongly-typed resource class, for looking up localized strings, etc.
|
||||
/// </summary>
|
||||
// This class was auto-generated by the StronglyTypedResourceBuilder
|
||||
// class via a tool like ResGen or Visual Studio.
|
||||
// To add or remove a member, edit your .ResX file then rerun ResGen
|
||||
// with the /str option, or rebuild your VS project.
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||||
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
|
||||
[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
|
||||
[global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
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||||
internal class Resources {
|
||||
|
||||
private static global::System.Resources.ResourceManager resourceMan;
|
||||
|
||||
private static global::System.Globalization.CultureInfo resourceCulture;
|
||||
|
||||
[global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
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||||
internal Resources() {
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||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Returns the cached ResourceManager instance used by this class.
|
||||
/// </summary>
|
||||
[global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
|
||||
internal static global::System.Resources.ResourceManager ResourceManager {
|
||||
get {
|
||||
if (object.ReferenceEquals(resourceMan, null)) {
|
||||
global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("CodeSampleCsharp.Properties.Resources", typeof(Resources).Assembly);
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||||
resourceMan = temp;
|
||||
}
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||||
return resourceMan;
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Overrides the current thread's CurrentUICulture property for all
|
||||
/// resource lookups using this strongly typed resource class.
|
||||
/// </summary>
|
||||
[global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
|
||||
internal static global::System.Globalization.CultureInfo Culture {
|
||||
get {
|
||||
return resourceCulture;
|
||||
}
|
||||
set {
|
||||
resourceCulture = value;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
+120
@@ -0,0 +1,120 @@
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||||
<?xml version="1.0" encoding="utf-8"?>
|
||||
<root>
|
||||
<!--
|
||||
Microsoft ResX Schema
|
||||
|
||||
Version 2.0
|
||||
|
||||
The primary goals of this format is to allow a simple XML format
|
||||
that is mostly human readable. The generation and parsing of the
|
||||
various data types are done through the TypeConverter classes
|
||||
associated with the data types.
|
||||
|
||||
Example:
|
||||
|
||||
... ado.net/XML headers & schema ...
|
||||
<resheader name="resmimetype">text/microsoft-resx</resheader>
|
||||
<resheader name="version">2.0</resheader>
|
||||
<resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
|
||||
<resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
|
||||
<data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
|
||||
<data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
|
||||
<data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
|
||||
<value>[base64 mime encoded serialized .NET Framework object]</value>
|
||||
</data>
|
||||
<data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
|
||||
<value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
|
||||
<comment>This is a comment</comment>
|
||||
</data>
|
||||
|
||||
There are any number of "resheader" rows that contain simple
|
||||
name/value pairs.
|
||||
|
||||
Each data row contains a name, and value. The row also contains a
|
||||
type or mimetype. Type corresponds to a .NET class that support
|
||||
text/value conversion through the TypeConverter architecture.
|
||||
Classes that don't support this are serialized and stored with the
|
||||
mimetype set.
|
||||
|
||||
The mimetype is used for serialized objects, and tells the
|
||||
ResXResourceReader how to depersist the object. This is currently not
|
||||
extensible. For a given mimetype the value must be set accordingly:
|
||||
|
||||
Note - application/x-microsoft.net.object.binary.base64 is the format
|
||||
that the ResXResourceWriter will generate, however the reader can
|
||||
read any of the formats listed below.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.binary.base64
|
||||
value : The object must be serialized with
|
||||
: System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
|
||||
: and then encoded with base64 encoding.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.soap.base64
|
||||
value : The object must be serialized with
|
||||
: System.Runtime.Serialization.Formatters.Soap.SoapFormatter
|
||||
: and then encoded with base64 encoding.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.bytearray.base64
|
||||
value : The object must be serialized into a byte array
|
||||
: using a System.ComponentModel.TypeConverter
|
||||
: and then encoded with base64 encoding.
|
||||
-->
|
||||
<xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
|
||||
<xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
|
||||
<xsd:element name="root" msdata:IsDataSet="true">
|
||||
<xsd:complexType>
|
||||
<xsd:choice maxOccurs="unbounded">
|
||||
<xsd:element name="metadata">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" use="required" type="xsd:string" />
|
||||
<xsd:attribute name="type" type="xsd:string" />
|
||||
<xsd:attribute name="mimetype" type="xsd:string" />
|
||||
<xsd:attribute ref="xml:space" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="assembly">
|
||||
<xsd:complexType>
|
||||
<xsd:attribute name="alias" type="xsd:string" />
|
||||
<xsd:attribute name="name" type="xsd:string" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="data">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
|
||||
<xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
|
||||
<xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
|
||||
<xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
|
||||
<xsd:attribute ref="xml:space" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="resheader">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" type="xsd:string" use="required" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
</xsd:choice>
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
</xsd:schema>
|
||||
<resheader name="resmimetype">
|
||||
<value>text/microsoft-resx</value>
|
||||
</resheader>
|
||||
<resheader name="version">
|
||||
<value>2.0</value>
|
||||
</resheader>
|
||||
<resheader name="reader">
|
||||
<value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
|
||||
</resheader>
|
||||
<resheader name="writer">
|
||||
<value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
|
||||
</resheader>
|
||||
</root>
|
||||
+9
@@ -0,0 +1,9 @@
|
||||
<Application x:Class="CodeSampleCsharp.App"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
|
||||
xmlns:local="clr-namespace:CodeSampleCsharp"
|
||||
StartupUri="MainWindow.xaml">
|
||||
<Application.Resources>
|
||||
|
||||
</Application.Resources>
|
||||
</Application>
|
||||
+9
@@ -0,0 +1,9 @@
|
||||
<Application x:Class="Application"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
|
||||
xmlns:local="clr-namespace:CodeSampleVb"
|
||||
StartupUri="MainWindow.xaml">
|
||||
<Application.Resources>
|
||||
|
||||
</Application.Resources>
|
||||
</Application>
|
||||
+6
@@ -0,0 +1,6 @@
|
||||
Class Application
|
||||
|
||||
' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
|
||||
' can be handled in this file.
|
||||
|
||||
End Class
|
||||
+11
@@ -0,0 +1,11 @@
|
||||
Imports System.Windows
|
||||
|
||||
'The ThemeInfo attribute describes where any theme specific and generic resource dictionaries can be found.
|
||||
'1st parameter: where theme specific resource dictionaries are located
|
||||
'(used if a resource is not found in the page,
|
||||
' or application resource dictionaries)
|
||||
|
||||
'2nd parameter: where the generic resource dictionary is located
|
||||
'(used if a resource is not found in the page,
|
||||
'app, and any theme specific resource dictionaries)
|
||||
<Assembly: ThemeInfo(ResourceDictionaryLocation.None, ResourceDictionaryLocation.SourceAssembly)>
|
||||
+22
@@ -0,0 +1,22 @@
|
||||
<Project Sdk="Microsoft.NET.Sdk">
|
||||
|
||||
<PropertyGroup>
|
||||
<OutputType>WinExe</OutputType>
|
||||
<TargetFramework>net6.0-windows</TargetFramework>
|
||||
<RootNamespace>CodeSampleVb</RootNamespace>
|
||||
<UseWPF>true</UseWPF>
|
||||
</PropertyGroup>
|
||||
|
||||
<ItemGroup>
|
||||
<Import Include="System.Windows" />
|
||||
<Import Include="System.Windows.Controls" />
|
||||
<Import Include="System.Windows.Data" />
|
||||
<Import Include="System.Windows.Documents" />
|
||||
<Import Include="System.Windows.Input" />
|
||||
<Import Include="System.Windows.Media" />
|
||||
<Import Include="System.Windows.Media.Imaging" />
|
||||
<Import Include="System.Windows.Navigation" />
|
||||
<Import Include="System.Windows.Shapes" />
|
||||
</ItemGroup>
|
||||
|
||||
</Project>
|
||||
+5
@@ -0,0 +1,5 @@
|
||||
<Window x:Class="CodeSampleVb.MainWindow"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:CodeSampleVb"
|
||||
Title="XAML loading and dependency properties" Height="100" Width="400">
|
||||
</Window>
|
||||
+62
@@ -0,0 +1,62 @@
|
||||
Namespace CodeSampleVb
|
||||
|
||||
' <summary>
|
||||
' Interaction logic for MainWindow.xaml.
|
||||
' </summary>
|
||||
Partial Public Class MainWindow
|
||||
Inherits Window
|
||||
|
||||
Public Sub New()
|
||||
InitializeComponent()
|
||||
|
||||
' Test code.
|
||||
Dim aquarium As New Aquarium With {
|
||||
.AquariumGraphic = New Uri("http://www.contoso.com/aquarium-graphic-new.jpg")
|
||||
}
|
||||
Debug.WriteLine($"Aquarium graphic: {aquarium.AquariumGraphic}")
|
||||
End Sub
|
||||
|
||||
' Output:
|
||||
' OnUriChanged http://www.contoso.com/aquarium-graphic-new.jpg
|
||||
' Aquarium graphic: http://www.contoso.com/aquarium-graphic-new.jpg
|
||||
End Class
|
||||
|
||||
Public Class Aquarium
|
||||
Inherits DependencyObject
|
||||
|
||||
'<DependencyPropertyWithWrapper>
|
||||
' Register a dependency property with the specified property name,
|
||||
' property type, owner type, and property metadata. Store the dependency
|
||||
' property identifier as a public static readonly member of the class.
|
||||
Public Shared ReadOnly AquariumGraphicProperty As DependencyProperty =
|
||||
DependencyProperty.Register(
|
||||
name:="AquariumGraphic",
|
||||
propertyType:=GetType(Uri),
|
||||
ownerType:=GetType(Aquarium),
|
||||
typeMetadata:=New FrameworkPropertyMetadata(
|
||||
defaultValue:=New Uri("http://www.contoso.com/aquarium-graphic.jpg"),
|
||||
flags:=FrameworkPropertyMetadataOptions.AffectsRender,
|
||||
propertyChangedCallback:=New PropertyChangedCallback(AddressOf OnUriChanged)))
|
||||
|
||||
' Property wrapper with get & set accessors.
|
||||
Public Property AquariumGraphic As Uri
|
||||
Get
|
||||
Return CType(GetValue(AquariumGraphicProperty), Uri)
|
||||
End Get
|
||||
Set
|
||||
SetValue(AquariumGraphicProperty, Value)
|
||||
End Set
|
||||
End Property
|
||||
|
||||
' Property-changed callback.
|
||||
Private Shared Sub OnUriChanged(dependencyObject As DependencyObject,
|
||||
e As DependencyPropertyChangedEventArgs)
|
||||
' Some custom logic that runs on effective property value change.
|
||||
Dim newValue As Uri = CType(dependencyObject.GetValue(AquariumGraphicProperty), Uri)
|
||||
Debug.WriteLine($"OnUriChanged: {newValue}")
|
||||
End Sub
|
||||
'</DependencyPropertyWithWrapper>
|
||||
|
||||
End Class
|
||||
|
||||
End Namespace
|
||||
@@ -0,0 +1,56 @@
|
||||
---
|
||||
title: "XAML loading and dependency properties"
|
||||
description: "Learn about Extensible Application Markup Language (XAML) loading of dependency property in Windows Presentation Foundation (WPF)."
|
||||
ms.date: "12/22/2021"
|
||||
dev_langs:
|
||||
- "csharp"
|
||||
- "vb"
|
||||
helpviewer_keywords:
|
||||
- "custom dependency properties [WPF]"
|
||||
- "dependency properties [WPF], XAML loading"
|
||||
- "loading XML data [WPF]"
|
||||
---
|
||||
<!-- The acrolinx score was 92 on 10/14/2021-->
|
||||
|
||||
# XAML loading and dependency properties (WPF .NET)
|
||||
|
||||
The Windows Presentation Foundation (WPF) implementation of its Extensible Application Markup Language (XAML) processor is inherently dependency property aware. As such, the XAML processor uses WPF property system methods to load XAML and process dependency property attributes, and entirely bypasses dependency property wrappers by using WPF property system methods like <xref:System.Windows.DependencyObject.GetValue%2A> and <xref:System.Windows.DependencyObject.SetValue%2A>. So, if you add custom logic to the property wrapper of your custom dependency property, it won't be called by the XAML processor when a property value is set in XAML.
|
||||
|
||||
[!INCLUDE [desktop guide under construction](../../includes/desktop-guide-preview-note.md)]
|
||||
|
||||
## Prerequisites
|
||||
|
||||
The article assumes a basic knowledge of dependency properties, and that you've read [Dependency properties overview](dependency-properties-overview.md). To follow the examples in this article, it helps if you're familiar with Extensible Application Markup Language (XAML) and know how to write WPF applications.
|
||||
|
||||
## WPF XAML loader performance
|
||||
|
||||
It's computationally less expensive for the WPF XAML processor to directly call <xref:System.Windows.DependencyObject.SetValue%2A> to set the value of a dependency property, rather than use the property wrapper of a dependency property.
|
||||
|
||||
If the XAML processor did use the property wrapper, it would require inferring the entire object model of the backing code based only on the type and member relationships indicated in markup. Although the type can be identified from markup by using a combination of `xmlns` and assembly attributes, identifying the members, determining which members can be set as an attribute, and resolving supported property value types, would require extensive reflection using <xref:System.Reflection.PropertyInfo>.
|
||||
|
||||
The WPF property system maintains a storage table of dependency properties implemented on a given <xref:System.Windows.DependencyObject> derived type. The XAML processor uses that table to infer the dependency property identifier for a dependency property. For example, by convention the dependency property identifier for a dependency property named `ABC` is `ABCProperty`. The XAML processor can efficiently set the value of any dependency property by calling the `SetValue` method on its containing type using the dependency property identifier.
|
||||
|
||||
For more information on dependency property wrappers, see [Custom dependency properties](custom-dependency-properties.md).
|
||||
|
||||
## Implications for custom dependency properties
|
||||
|
||||
The WPF XAML processor bypasses property wrappers and directly calls <xref:System.Windows.DependencyObject.SetValue%2A> to set a dependency property value. So, avoid putting any extra logic in the `set` accessor of your custom dependency property because that logic won't run when a property value is set in XAML. The `set` accessor should only contain a `SetValue` call.
|
||||
|
||||
Similarly, aspects of the WPF XAML processor that get property values bypass the property wrapper and directly call <xref:System.Windows.DependencyObject.GetValue%2A>. So, also avoid putting any extra logic in the `get` accessor of your custom dependency property because that logic won't run when a property value is read in XAML. The `get` accessor should only contain a `GetValue` call.
|
||||
|
||||
## Dependency property with wrapper example
|
||||
|
||||
The following example shows a recommended dependency property definition with property wrappers. The dependency property identifier is stored as a `public static readonly` field, and the `get` and `set` accessors contain no code beyond the necessary WPF property system methods that back the dependency property value. If you have code that needs to run when the value of your dependency property changes, consider putting that code in the <xref:System.Windows.PropertyChangedCallback> for your dependency property. For more information, see [Property-changed callbacks](/dotnet/desktop/wpf/properties/dependency-property-callbacks-and-validation?preserve-view=true#property-changed-callbacks).
|
||||
|
||||
:::code language="csharp" source="./snippets/xaml-loading-and-dependency-properties/csharp/MainWindow.xaml.cs" id="DependencyPropertyWithWrapper":::
|
||||
:::code language="vb" source="./snippets/xaml-loading-and-dependency-properties/vb/MainWindow.xaml.vb" id="DependencyPropertyWithWrapper":::
|
||||
|
||||
## See also
|
||||
|
||||
- [Dependency properties overview](dependency-properties-overview.md)
|
||||
- [XAML in WPF](/dotnet/desktop/wpf/advanced/xaml-in-wpf?view=netframeworkdesktop-4.8&preserve-view=true)
|
||||
- [Custom dependency properties](custom-dependency-properties.md)
|
||||
- [Dependency property metadata](dependency-property-metadata.md)
|
||||
- [Collection-type dependency properties](collection-type-dependency-properties.md)
|
||||
- [Dependency property security](dependency-property-security.md)
|
||||
- [Safe constructor patterns for DependencyObjects](/dotnet/desktop/wpf/advanced/safe-constructor-patterns-for-dependencyobjects?view=netframeworkdesktop-4.8&preserve-view=true)
|
||||
@@ -102,6 +102,8 @@ items:
|
||||
href: properties/dependency-property-security.md
|
||||
- name: Safe constructor patterns for DependencyObjects
|
||||
href: properties/safe-constructor-patterns-for-dependencyobjects.md
|
||||
- name: XAML loading and dependency properties
|
||||
href: properties/xaml-loading-and-dependency-properties.md
|
||||
- name: Common tasks
|
||||
items:
|
||||
- name: Implement a dependency property
|
||||
|
||||
@@ -395,6 +395,10 @@
|
||||
"SourceUrl": "/dotnet/desktop/wpf/advanced/safe-constructor-patterns-for-dependencyobjects?view=netframeworkdesktop-4.8",
|
||||
"TargetUrl": "/dotnet/desktop/wpf/properties/safe-constructor-patterns-for-dependencyobjects?view=netdesktop-6.0"
|
||||
},
|
||||
{
|
||||
"SourceUrl": "/dotnet/desktop/wpf/advanced/xaml-loading-and-dependency-properties?view=netframeworkdesktop-4.8",
|
||||
"TargetUrl": "/dotnet/desktop/wpf/properties/xaml-loading-and-dependency-properties?view=netdesktop-6.0"
|
||||
},
|
||||
|
||||
// Systems - XAML
|
||||
{
|
||||
|
||||
Reference in New Issue
Block a user