Content update - Read-only dependency properties (user story 1878471) (#1230)

* Improve collection-type dp snippets that are readonly.

* Add article, snippets, toc, and redirects

* Minor edit

* Update target framework to .NET 6.0

.openpublishing.redirection.json

@@ -556,6 +556,14 @@
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             "redirect_url": "/dotnet/desktop/wpf/advanced/dependency-property-callbacks-and-validation?view=netframeworkdesktop-4.8"
+        },
+        {
+            "source_path": "dotnet-desktop-guide/net/wpf/advanced/read-only-dependency-properties.md",
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+            "source_path": "dotnet-desktop-guide/framework/wpf/properties/read-only-dependency-properties.md",
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 }

dotnet-desktop-guide/net/wpf/properties/read-only-dependency-properties.md

@@ -0,0 +1,67 @@
+---
+title: "Read-only dependency properties"
+description: Learn about dependency properties in Windows Presentation Foundation (WPF) and how to create a read-only dependency property.
+ms.date: "11/29/2021"
+dev_langs:
+  - "csharp"
+  - "vb"
+helpviewer_keywords:
+  - "dependency properties [WPF], read-only"
+  - "read-only dependency properties [WPF]"
+---
+<!-- The acrolinx score was 94 on 11/29/2021-->
+
+# Read-only dependency properties (WPF .NET)
+
+You can use read-only dependency properties to prevent property values being set from outside your code. This article discusses existing read-only dependency properties and the scenarios and techniques for creating a custom read-only dependency property.
+
+[!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.
+
+## Existing read-only dependency properties
+
+Read-only dependency properties typically report state, and shouldn't be modifiable through a `public` accessor. For example, the Windows Presentation Foundation (WPF) framework implements the <xref:System.Windows.UIElement.IsMouseOver%2A> property as read-only because its value should only be determined by mouse input. If `IsMouseOver` allowed other inputs, its value might become inconsistent with mouse input. Though not settable through a `public` accessor, many existing read-only dependency properties have values determined by multiple inputs.
+
+## Uses of read-only dependency properties
+
+Read-only dependency properties aren't applicable in several scenarios where dependency properties normally offer a solution. Non-applicable scenarios include data binding, applying a style to a value, validation, animation, and inheritance. However, a read-only dependency property can be used as a property trigger in a style. For example, <xref:System.Windows.UIElement.IsMouseOver%2A> is commonly used to trigger changes to the background, foreground, or other visible property of a control when the mouse is over it. The WPF property system detects and reports changes in read-only dependency properties, thus supporting property trigger functionality. Read-only dependency properties are also useful when implementing a collection-type dependency property where only the collection elements need to be writeable, not the collection object itself. For more information, see [Collection-type dependency properties](collection-type-dependency-properties.md).
+
+> [!NOTE]
+> Only dependency properties, not regular common language runtime properties, can be used as property triggers in a style.
+
+## Creating custom read-only dependency properties
+
+Before creating a dependency property that's read-only, check the [non-applicable scenarios](#uses-of-read-only-dependency-properties).
+
+The process of creating a read-only dependency property is in many ways similar to creating read-write dependency properties, with these distinctions:
+
+- When registering your read-only property, call <xref:System.Windows.DependencyProperty.RegisterReadOnly%2A> instead of <xref:System.Windows.DependencyProperty.Register%2A>.
+
+- When implementing the CLR property wrapper, make sure it doesn't have a public `set` accessor.
+
+- `RegisterReadOnly` returns <xref:System.Windows.DependencyPropertyKey> instead of <xref:System.Windows.DependencyProperty>. Store the `DependencyPropertyKey` in a nonpublic class member.
+
+You can determine the value of your read-only dependency property using whatever logic you choose. The recommended way to set the property value, either initially or as part of runtime logic, is to use the overload of <xref:System.Windows.DependencyObject.SetValue%2A> that accepts a parameter of type `DependencyPropertyKey`. Using `SetValue` is preferable to circumventing the property system and setting the backing field directly.
+
+How and where you set the value of a read-only dependency property within your application will affect the access level you assign to the class member that stores the `DependencyPropertyKey`. If you only set the property value from within the class that registers the dependency property, you can use a `private` access modifier. For scenarios where the values of dependency properties affect each other, you can use paired <xref:System.Windows.PropertyChangedCallback> and <xref:System.Windows.CoerceValueCallback> callbacks to trigger value changes. For more information, see [Dependency property metadata](dependency-property-metadata.md).
+
+If you need to change the value of a read-only dependency property from outside the class that registers it, you can use an `internal` access modifier for the `DependencyPropertyKey`. For example, you might call `SetValue` from an event handler in the same assembly. The following example defines an Aquarium class that calls `RegisterReadOnly` to create the read-only dependency property `FishCount`. The `DependencyPropertyKey` is assigned to an `internal static readonly` field, so that code in the same assembly can change the read-only dependency property value.
+
+:::code language="csharp" source="./snippets/read-only-dependency-properties/csharp/MainWindow.xaml.cs" id="RegisterReadOnlyDependencyProperty":::
+:::code language="vb" source="./snippets/read-only-dependency-properties/vb/MainWindow.xaml.vb" id="RegisterReadOnlyDependencyProperty":::
+
+Because the WPF property system doesn't propagate the <xref:System.Windows.DependencyPropertyKey> outside your code, read-only dependency properties have better write security than read-write dependency properties. Use a read-only dependency property when you want to limit write-access to those who have a reference to the `DependencyPropertyKey`.
+
+In contrast, the dependency property identifier for read-write dependency properties is accessible through the property system, no matter what access modifier you assign it. For more information, see [Dependency property security](/dotnet/desktop/wpf/advanced/dependency-property-security?view=netframeworkdesktop-4.8&preserve-view=true).
+
+## See also
+
+- [Dependency properties overview](dependency-properties-overview.md)
+- [Implement a Dependency property](how-to-implement-a-dependency-property.md)
+- [Custom dependency properties](custom-dependency-properties.md)
+- [Collection-type dependency properties](collection-type-dependency-properties.md)
+- [Dependency property security](/dotnet/desktop/wpf/advanced/dependency-property-security?view=netframeworkdesktop-4.8&preserve-view=true)
+- [Styles and templates in WPF](/dotnet/desktop/wpf/controls/styles-templates-overview)

dotnet-desktop-guide/net/wpf/properties/snippets/collection-type-dependency-properties/csharp/MainWindow.xaml

@@ -1,11 +1,12 @@
 <Window x:Class="CodeSampleCsharp.MainWindow"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:src="clr-namespace:CodeSampleCsharp"
-        Title="Collection-Type Dependency Properties" Height="100" Width="400">
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Collection-Type Dependency Properties" Height="100" Width="500">
 
     <StackPanel>
 
-        <Button Click="InitializeAquariums">Set collection default value in class constructor</Button>
+        <Button Click="InitializeAquariums">Set collection default value in class constructor (Aquarium)</Button>
+        <Button Click="InitializeFreezableAquariums">Set collection default value in class constructor (FreezableCollection Aquarium)</Button>
 
     </StackPanel>
 </Window>

dotnet-desktop-guide/net/wpf/properties/snippets/collection-type-dependency-properties/csharp/MainWindow.xaml.cs

@@ -16,10 +16,15 @@ namespace CodeSampleCsharp
             aquarium1.AquariumContents.Add(new Fish());
             aquarium2.AquariumContents.Add(new Fish());
             MessageBox.Show(
-                $"Aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
-                $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish");
+                $"aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
+                $"aquarium2 contains {aquarium2.AquariumContents.Count} fish");
         }
         //</InitializeAquariums>
+
+        private void InitializeFreezableAquariums(object sender, RoutedEventArgs e)
+        {
+            FreezableCollectionAquarium.InitializeAquariums();
+        }
     }
 
     //<SetCollectionDefaultValueInConstructor>
@@ -36,16 +41,12 @@ namespace CodeSampleCsharp
               //typeMetadata: new FrameworkPropertyMetadata(new List<FrameworkElement>())
             );
 
-        // Store the dependency property identifier as a static member of the class.
-        public static readonly DependencyProperty AquariumContentsProperty =
-            s_aquariumContentsPropertyKey.DependencyProperty;
-
         // Set the default collection value in a class constructor.
         public Aquarium() => SetValue(s_aquariumContentsPropertyKey, new List<FrameworkElement>());
 
-        // Declare a read-only property.
+        // Declare a public get accessor.
         public List<FrameworkElement> AquariumContents =>
-            (List<FrameworkElement>)GetValue(AquariumContentsProperty);
+            (List<FrameworkElement>)GetValue(s_aquariumContentsPropertyKey.DependencyProperty);
     }
 
     public class Fish : FrameworkElement { }
@@ -61,8 +62,8 @@ namespace CodeSampleCsharp
             aquarium2.AquariumContents.Add(new Fish());
             aquarium2.AquariumContents = new List<FrameworkElement>();
             MessageBox.Show(
-                $"Aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
-                $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish");
+                $"aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
+                $"aquarium2 contains {aquarium2.AquariumContents.Count} fish");
         }
 
         //<ReadWriteDependencyProperty>
@@ -81,7 +82,7 @@ namespace CodeSampleCsharp
             // Set the default collection value in a class constructor.
             public Aquarium() => SetValue(AquariumContentsProperty, new List<FrameworkElement>());
 
-            // Declare a read-write property.
+            // Declare public get and set accessors.
             public List<FrameworkElement> AquariumContents
             {
                 get => (List<FrameworkElement>)GetValue(AquariumContentsProperty);
@@ -102,8 +103,8 @@ namespace CodeSampleCsharp
             aquarium1.AquariumContents.Add(new Fish());
             aquarium2.AquariumContents.Add(new Fish());
             MessageBox.Show(
-                $"Aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
-                $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish");
+                $"FreezableCollection aquarium1 contains {aquarium1.AquariumContents.Count} fish\r\n" +
+                $"FreezableCollection aquarium2 contains {aquarium2.AquariumContents.Count} fish");
         }
 
         //<FreezableCollectionAquarium>
@@ -126,11 +127,10 @@ namespace CodeSampleCsharp
             // Set the default collection value in a class constructor.
             public Aquarium() => SetValue(s_aquariumContentsPropertyKey, new FreezableCollection<FrameworkElement>());
 
-            // Declare a read-only property.
+            // Declare a public get accessor.
             public FreezableCollection<FrameworkElement> AquariumContents =>
                 (FreezableCollection<FrameworkElement>)GetValue(AquariumContentsProperty);
         }
-
         //</FreezableCollectionAquarium>
 
         public class Fish : FrameworkElement { }

dotnet-desktop-guide/net/wpf/properties/snippets/collection-type-dependency-properties/vb/MainWindow.xaml

@@ -1,11 +1,12 @@
 <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:CodeSampleCsharp"
-        Title="Collection-Type Dependency Properties" Height="100" Width="400">
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Collection-Type Dependency Properties" Height="100" Width="500">
 
     <StackPanel>
 
-        <Button Click="InitializeAquariums">Set collection default value in class constructor</Button>
+        <Button Click="InitializeAquariums">Set collection default value in class constructor (Aquarium)</Button>
+        <Button Click="InitializeFreezableAquariums">Set collection default value in class constructor (FreezableCollection Aquarium)</Button>
 
     </StackPanel>
 </Window>

dotnet-desktop-guide/net/wpf/properties/snippets/collection-type-dependency-properties/vb/MainWindow.xaml.vb

@@ -16,11 +16,15 @@
             Dim aquarium2 As New Aquarium()
             aquarium1.AquariumContents.Add(New Fish())
             aquarium2.AquariumContents.Add(New Fish())
-            MessageBox.Show($"Aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
-                            $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish")
+            MessageBox.Show($"aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
+                            $"aquarium2 contains {aquarium2.AquariumContents.Count} fish")
         End Sub
         '</InitializeAquariums>
 
+        Private Sub InitializeFreezableAquariums(sender As Object, e As RoutedEventArgs)
+            FreezableCollectionAquarium.InitializeAquariums()
+        End Sub
+
     End Class
 
     '<SetCollectionDefaultValueInConstructor>
@@ -37,19 +41,15 @@
                 typeMetadata:=New FrameworkPropertyMetadata())
                 'typeMetadata:=New FrameworkPropertyMetadata(New List(Of FrameworkElement)))
 
-        ' Store the dependency property identifier as a static member of the class.
-        Public Shared ReadOnly AquariumContentsProperty As DependencyProperty =
-            s_aquariumContentsPropertyKey.DependencyProperty
-
         ' Set the default collection value in a class constructor.
         Public Sub New()
             SetValue(s_aquariumContentsPropertyKey, New List(Of FrameworkElement)())
         End Sub
 
-        ' Declare a read-only property.
+        ' Declare a public get accessor.
         Public ReadOnly Property AquariumContents As List(Of FrameworkElement)
             Get
-                Return CType(GetValue(AquariumContentsProperty), List(Of FrameworkElement))
+                Return CType(GetValue(s_aquariumContentsPropertyKey.DependencyProperty), List(Of FrameworkElement))
             End Get
         End Property
     End Class
@@ -67,8 +67,8 @@
             aquarium1.AquariumContents.Add(New Fish())
             aquarium2.AquariumContents.Add(New Fish())
             aquarium2.AquariumContents = New List(Of FrameworkElement)()
-            MessageBox.Show($"Aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
-                            $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish")
+            MessageBox.Show($"aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
+                            $"aquarium2 contains {aquarium2.AquariumContents.Count} fish")
         End Sub
 
         '<ReadWriteDependencyProperty>
@@ -89,7 +89,7 @@
                 SetValue(AquariumContentsProperty, New List(Of FrameworkElement)())
             End Sub
 
-            ' Declare a read-write property.
+            ' Declare public get and set accessors.
             Public Property AquariumContents As List(Of FrameworkElement)
                 Get
                     Return CType(GetValue(AquariumContentsProperty), List(Of FrameworkElement))
@@ -114,8 +114,8 @@
             Dim aquarium2 As New Aquarium()
             aquarium1.AquariumContents.Add(New Fish())
             aquarium2.AquariumContents.Add(New Fish())
-            MessageBox.Show($"Aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
-                            $"Aquarium2 contains {aquarium2.AquariumContents.Count} fish")
+            MessageBox.Show($"FreezableCollection aquarium1 contains {aquarium1.AquariumContents.Count} fish{Environment.NewLine}" +
+                            $"FreezableCollection aquarium2 contains {aquarium2.AquariumContents.Count} fish")
         End Sub
 
         '<FreezableCollectionAquarium>
@@ -131,19 +131,15 @@
                     ownerType:=GetType(Aquarium),
                     typeMetadata:=New FrameworkPropertyMetadata())
 
-            ' Store the dependency property identifier as a static member of the class.
-            Public Shared ReadOnly AquariumContentsProperty As DependencyProperty =
-                s_aquariumContentsPropertyKey.DependencyProperty
-
             ' Set the default collection value in a class constructor.
             Public Sub New()
                 SetValue(s_aquariumContentsPropertyKey, New FreezableCollection(Of FrameworkElement)())
             End Sub
 
-            ' Declare a read-only property.
+            ' Declare a public get accessor.
             Public ReadOnly Property AquariumContents As FreezableCollection(Of FrameworkElement)
                 Get
-                    Return CType(GetValue(AquariumContentsProperty), FreezableCollection(Of FrameworkElement))
+                    Return CType(GetValue(s_aquariumContentsPropertyKey.DependencyProperty), FreezableCollection(Of FrameworkElement))
                 End Get
             End Property
         End Class

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/App.xaml.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Configuration;
+using System.Data;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace CodeSampleCsharp
+{
+    /// <summary>
+    /// Interaction logic for App.xaml
+    /// </summary>
+    public partial class App : Application
+    {
+    }
+}

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/AssemblyInfo.cs

@@ -0,0 +1,10 @@
+using System.Windows;
+
+[assembly: ThemeInfo(
+    ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
+                                     //(used if a resource is not found in the page,
+                                     // or application resource dictionaries)
+    ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
+                                              //(used if a resource is not found in the page,
+                                              // app, or any theme specific resource dictionaries)
+)]

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/CodeSampleCsharp.csproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net6.0-windows</TargetFramework>
+    <UseWPF>true</UseWPF>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Update="Properties\Resources.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Resources.resx</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="Properties\Resources.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>Resources.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+  </ItemGroup>
+
+</Project>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/MainWindow.xaml

@@ -0,0 +1,12 @@
+<Window x:Class="CodeSampleCsharp.MainWindow"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Readonly dependency properties" Height="100" Width="400">
+
+    <StackPanel>
+
+        <Button Click="Button_Click">Increment property value</Button>
+        <Label Name="lblFishCount" Content="Aquarium fish count: 0"/>
+
+    </StackPanel>
+</Window>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/MainWindow.xaml.cs

@@ -0,0 +1,38 @@
+using System.Windows;
+
+namespace CodeSampleCsharp
+{
+    /// <summary>
+    /// Interaction logic for MainWindow.xaml.
+    /// </summary>
+    public partial class MainWindow : Window
+    {
+        readonly Aquarium _aquarium = new();
+
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            // Test setting a value.
+            _aquarium.SetValue(Aquarium.FishCountPropertyKey, _aquarium.FishCount + 1);
+            lblFishCount.Content = $"Aquarium fish count: {_aquarium.FishCount}";
+        }
+    }
+
+    //<RegisterReadOnlyDependencyProperty>
+    public class Aquarium : DependencyObject
+    {
+        // Register a dependency property with the specified property name,
+        // property type, owner type, and property metadata.
+        // Assign DependencyPropertyKey to a nonpublic field.
+        internal static readonly DependencyPropertyKey FishCountPropertyKey =
+            DependencyProperty.RegisterReadOnly(
+              name: "FishCount",
+              propertyType: typeof(int),
+              ownerType: typeof(Aquarium),
+              typeMetadata: new FrameworkPropertyMetadata());
+
+        // Declare a public get accessor.
+        public int FishCount =>
+            (int)GetValue(FishCountPropertyKey.DependencyProperty);
+    }
+    //</RegisterReadOnlyDependencyProperty>
+}

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/Properties/Resources.Designer.cs

@@ -0,0 +1,63 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace CodeSampleCsharp.Properties {
+    using System;
+    
+    
+    /// <summary>
+    ///   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.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    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")]
+        internal Resources() {
+        }
+        
+        /// <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);
+                    resourceMan = temp;
+                }
+                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;
+            }
+        }
+    }
+}

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/Properties/Resources.resx

@@ -0,0 +1,120 @@
+<?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>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/csharp/app.xaml

@@ -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>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/Application.xaml

@@ -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>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/Application.xaml.vb

@@ -0,0 +1,6 @@
+Class Application
+
+    ' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
+    ' can be handled in this file.
+
+End Class

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/AssemblyInfo.vb

@@ -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)>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/CodeSampleVb.vbproj

@@ -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>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/MainWindow.xaml

@@ -0,0 +1,12 @@
+<Window x:Class="CodeSampleVb.MainWindow"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Readonly dependency properties" Height="100" Width="400">
+
+    <StackPanel>
+        
+        <Button Click="Button_Click">Increment property value</Button>
+        <Label Name="lblFishCount" Content="Aquarium fish count: 0"/>
+
+    </StackPanel>
+</Window>

dotnet-desktop-guide/net/wpf/properties/snippets/read-only-dependency-properties/vb/MainWindow.xaml.vb

@@ -0,0 +1,47 @@
+Namespace CodeSampleVb
+
+    ' <summary>
+    ' Interaction logic for MainWindow.xaml.
+    ' </summary>
+    Partial Public Class MainWindow
+        Inherits Window
+
+        ReadOnly _aquarium As New Aquarium()
+
+        Public Sub New()
+            InitializeComponent()
+        End Sub
+
+        Private Sub Button_Click(sender As Object, e As RoutedEventArgs)
+            ' Test setting a value.
+            _aquarium.SetValue(Aquarium.FishCountPropertyKey, _aquarium.FishCount + 1)
+            lblFishCount.Content = $"Aquarium fish count: {_aquarium.FishCount}"
+        End Sub
+
+    End Class
+
+    '<RegisterReadOnlyDependencyProperty>
+    Public Class Aquarium
+        Inherits DependencyObject
+
+        ' Register a dependency property with the specified property name,
+        ' property type, owner type, And property metadata.
+        ' Assign DependencyPropertyKey to a nonpublic field.
+        Friend Shared ReadOnly FishCountPropertyKey As DependencyPropertyKey =
+            DependencyProperty.RegisterReadOnly(
+                name:="FishCount",
+                propertyType:=GetType(Integer),
+                ownerType:=GetType(Aquarium),
+                typeMetadata:=New FrameworkPropertyMetadata())
+
+        ' Declare a public get accessor.
+        Public ReadOnly Property FishCount As Integer
+            Get
+                Return GetValue(FishCountPropertyKey.DependencyProperty)
+            End Get
+        End Property
+
+    End Class
+    '</RegisterReadOnlyDependencyProperty>
+
+End Namespace

dotnet-desktop-guide/net/wpf/toc.yml

@@ -94,6 +94,8 @@ items:
       href: properties/dependency-property-metadata.md
     - name: Dependency property callbacks and validation
       href: properties/dependency-property-callbacks-and-validation.md
+    - name: Read-only dependency properties
+      href: properties/read-only-dependency-properties.md
     - name: Common tasks
       items:
       - name: Implement a dependency property

redirects_generator/definitions.json

@@ -378,6 +378,11 @@
             "SourceUrl": "/dotnet/desktop/wpf/advanced/dependency-property-callbacks-and-validation?view=netframeworkdesktop-4.8",
             "TargetUrl": "/dotnet/desktop/wpf/properties/dependency-property-callbacks-and-validation?view=netdesktop-6.0"
         },
+        {
+            "Redirect": "TwoWay",
+            "SourceUrl": "/dotnet/desktop/wpf/advanced/read-only-dependency-properties?view=netframeworkdesktop-4.8",
+            "TargetUrl": "/dotnet/desktop/wpf/properties/read-only-dependency-properties?view=netdesktop-6.0"
+        },
 
         // Systems - XAML
         {