DependencyPropertyGenerator

Dependency property, routed event and weak event source generator for WPF/UWP/WinUI/Uno/Avalonia/MAUI platforms.

Usage

using DependencyPropertyGenerator;
using System.Windows.Controls;

#nullable enable

namespace H.Generators.IntegrationTests;

[DependencyProperty<bool>("IsSpinning", DefaultValue = true, Category = "Category", Description = "Description")]
public partial class MyControl : UserControl
{
    // Optional
    partial void OnIsSpinningChanged(bool oldValue, bool newValue)
    {
    }
}

[AttachedDependencyProperty<object, TreeView>("SelectedItem", DefaultBindingMode = DefaultBindingMode.TwoWay)]
public static partial class TreeViewExtensions
{
    // Optional
    static partial void OnSelectedItemChanged(TreeView sender, object? oldValue, object? newValue)
    {
    }
}

will generate:

//HintName: MyControl.Properties.IsSpinning.generated.cs

#nullable enable

namespace H.Generators.IntegrationTests
{
    public partial class MyControl
    {
        /// <summary>
        /// Description<br/>
        /// Default value: true
        /// </summary>
        public static readonly global::System.Windows.DependencyProperty IsSpinningProperty =
            global::System.Windows.DependencyProperty.Register(
                name: "IsSpinning",
                propertyType: typeof(bool),
                ownerType: typeof(global::H.Generators.IntegrationTests.MyControl),
                typeMetadata: new global::System.Windows.FrameworkPropertyMetadata(
                    defaultValue: (bool)true,
                    flags: global::System.Windows.FrameworkPropertyMetadataOptions.None,
                    propertyChangedCallback: static (sender, args) =>
                    {
                        ((global::H.Generators.IntegrationTests.MyControl)sender).OnIsSpinningChanged(
                            (bool)args.OldValue,
                            (bool)args.NewValue);
                    },
                    coerceValueCallback: null,
                    isAnimationProhibited: false),
                validateValueCallback: null);

        /// <summary>
        /// Description<br/>
        /// Default value: true
        /// </summary>
        [global::System.ComponentModel.Category("Category")]
        [global::System.ComponentModel.Description("Description")]
        public bool IsSpinning
        {
            get => (bool)GetValue(IsSpinningProperty);
            set => SetValue(IsSpinningProperty, value);
        }

        partial void OnIsSpinningChanged();
        partial void OnIsSpinningChanged(bool newValue);
        partial void OnIsSpinningChanged(bool oldValue, bool newValue);
    }
}

//HintName: TreeViewExtensions.AttachedProperties.SelectedItem.generated.cs

#nullable enable

namespace H.Generators.IntegrationTests
{
    public static partial class TreeViewExtensions
    {
        /// <summary>
        /// Default value: default(object)
        /// </summary>
        public static readonly global::System.Windows.DependencyProperty SelectedItemProperty =
            global::System.Windows.DependencyProperty.RegisterAttached(
                name: "SelectedItem",
                propertyType: typeof(object),
                ownerType: typeof(global::H.Generators.IntegrationTests.TreeViewExtensions),
                defaultMetadata: new global::System.Windows.FrameworkPropertyMetadata(
                    defaultValue: default(object),
                    flags: global::System.Windows.FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                    propertyChangedCallback: static (sender, args) =>
                    {
                        OnSelectedItemChanged(
                            (global::System.Windows.Controls.TreeView)sender,
                            (object?)args.OldValue,
                            (object?)args.NewValue);
                    },
                    coerceValueCallback: null,
                    isAnimationProhibited: false),
                validateValueCallback: null);

        /// <summary>
        /// Default value: default(object)
        /// </summary>
        public static void SetSelectedItem(global::System.Windows.DependencyObject element, object? value)
        {
            element = element ?? throw new global::System.ArgumentNullException(nameof(element));

            element.SetValue(SelectedItemProperty, value);
        }

        /// <summary>
        /// Default value: default(object)
        /// </summary>
        [global::System.Windows.AttachedPropertyBrowsableForType(typeof(global::System.Windows.Controls.TreeView))]
        public static object? GetSelectedItem(global::System.Windows.DependencyObject element)
        {
            element = element ?? throw new global::System.ArgumentNullException(nameof(element));

            return (object?)element.GetValue(SelectedItemProperty);
        }

        static partial void OnSelectedItemChanged();
        static partial void OnSelectedItemChanged(global::System.Windows.Controls.TreeView treeView);
        static partial void OnSelectedItemChanged(global::System.Windows.Controls.TreeView treeView, object? newValue);
        static partial void OnSelectedItemChanged(global::System.Windows.Controls.TreeView treeView, object? oldValue, object? newValue);
    }
}

Advanced usage

new object/struct() expressions in DefaultValue

While it's generally not recommended to use new expressions in properties, a generator provides this capability:

public readonly record struct Data();

[AttachedDependencyProperty<object, TreeView>("SelectedItem", DefaultValueExpression = "new Data()")]

If your type is declared outside the namespace of an attribute declaration, you will need to specify the full name of the type, including the namespace.

XML documentation

The easiest way to add documentation is the Description parameter. It will add a System.ComponentModel.Description attribute to the property and will also be used in the xml documentation.
If for some reason you need to save raw xml documentation for your properties, there is an option to specify raw xml text for both DependencyProperty and getter/setter via XmlDocumentation/PropertyXmlDocumentation attribute properties.

Platform detection

For some platforms there is no automatic detection. In these cases, the generator needs a little help by adding:

  <PropertyGroup>
    <DefineConstants>$(DefineConstants);HAS_UNO</DefineConstants>
    <DefineConstants>$(DefineConstants);HAS_UNO_WINUI</DefineConstants>
    <DefineConstants>$(DefineConstants);HAS_AVALONIA</DefineConstants>
  </PropertyGroup>

Automatic detection of Uno was added in Uno 4.5.

Bind event

The generator can automatically control properties that depend on events:

[AttachedDependencyProperty<object, Grid>("BindEventProperty", BindEvent = nameof(Grid.MouseWheel))]
public static partial class GridExtensions
{
    private static void OnBindEventPropertyChanged_MouseWheel(object? sender, System.Windows.Input.MouseWheelEventArgs args)
    {
    }
}

will generate additional code:

static partial void OnBindEventPropertyChanged_BeforeBind(
    global::System.Windows.Controls.Grid sender,
    object? oldValue,
    object? newValue);
static partial void OnBindEventPropertyChanged_AfterBind(
    global::System.Windows.Controls.Grid sender,
    object? oldValue,
    object? newValue);

static partial void OnBindEventPropertyChanged(
    global::System.Windows.Controls.Grid sender,
    object? oldValue,
    object? newValue)
{
    OnBindEventPropertyChanged_BeforeBind(
        sender,
        oldValue,
        newValue);

    if (oldValue is not default(object))
    {
        sender.MouseWheel -= OnBindEventPropertyChanged_MouseWheel;
    }
    if (newValue is not default(object))
    {
        sender.MouseWheel += OnBindEventPropertyChanged_MouseWheel;
    }

    OnBindEventPropertyChanged_AfterBind(
        sender,
        oldValue,
        newValue);
}

Override metadata

For UWP/WinUI/Uno, a special RegisterPropertyChangedCallbacks() method will be created, which you will need to call in the constructor to register property change callbacks.

Notes

To use generic attributes, you need to set up LangVersion in your .csproj:

<LangVersion>preview</LangVersion>

There are also non-Generic attributes here.

Possible features

• Mutable default values in constructor

Support

Priority place for bugs: https://github.com/HavenDV/DependencyPropertyGenerator/issues
Priority place for ideas and general questions: https://github.com/HavenDV/DependencyPropertyGenerator/discussions
I also have a Discord support channel:
https://discord.gg/g8u2t9dKgE