Patch Component render function

src/Avalonia.FuncUI.sln

@@ -88,6 +88,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Elmish Examples", "Elmish E
 EndProject
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Examples.Elmish.Tetris", "Examples\Elmish Examples\Examples.Elmish.Tetris\Examples.Elmish.Tetris.fsproj", "{EC63B886-E809-4B74-B533-BFF3D60017C9}"
 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Examples.ComponentPlayground", "Examples\Examples.ComponentPlayground\Examples.ComponentPlayground.fsproj", "{FA4E81D2-1083-43E1-99E3-0F4EA31B3701}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -206,6 +208,10 @@ Global
 		{EC63B886-E809-4B74-B533-BFF3D60017C9}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{EC63B886-E809-4B74-B533-BFF3D60017C9}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{EC63B886-E809-4B74-B533-BFF3D60017C9}.Release|Any CPU.Build.0 = Release|Any CPU
+		{FA4E81D2-1083-43E1-99E3-0F4EA31B3701}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{FA4E81D2-1083-43E1-99E3-0F4EA31B3701}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{FA4E81D2-1083-43E1-99E3-0F4EA31B3701}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{FA4E81D2-1083-43E1-99E3-0F4EA31B3701}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -242,6 +248,7 @@ Global
 		{70BDCE72-149A-435A-9910-E79DE329F978} = {F50826CE-D9BC-45CF-A110-C42225B75AD3}
 		{6D2C62FC-5634-4997-AF1F-2E8A5D27E117} = {84811DB3-C276-4F0D-B3BA-78B88E2C6EF0}
 		{EC63B886-E809-4B74-B533-BFF3D60017C9} = {6D2C62FC-5634-4997-AF1F-2E8A5D27E117}
+		{FA4E81D2-1083-43E1-99E3-0F4EA31B3701} = {F50826CE-D9BC-45CF-A110-C42225B75AD3}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {4630E817-6780-4C98-9379-EA3B45224339}

src/Avalonia.FuncUI/Avalonia.FuncUI.fsproj

@@ -56,6 +56,7 @@
     <Compile Include="Helpers.fs" />
     <Compile Include="DSL\ViewBuilder.fs" />
     <Compile Include="DSL\AttrBuilder.fs" />
+    <Compile Include="DSL\Component.fs" />
     <Compile Include="DSL\View.fs" />
     <Compile Include="DSL\Base\AvaloniaObject.fs" />
 
@@ -169,6 +170,7 @@
     <Compile Include="Experimental\Experimental.EnvironmentState.fs" />
     <Compile Include="Experimental\Experimental.Operators.fs" />
     <Compile Include="Experimental\Experimental.Hooks.fs" />
+    <Compile Include="Experimental\Experimental.ClosureComponent.fs" />
   </ItemGroup>
 
 </Project>

src/Avalonia.FuncUI/Components/Component.fs

@@ -1,27 +1,13 @@
 namespace Avalonia.FuncUI
 
-open System
 open System.Diagnostics.CodeAnalysis
-open Avalonia.Controls
 open Avalonia.FuncUI
 open Avalonia.FuncUI.Types
-open Avalonia.FuncUI.VirtualDom
-open Avalonia.Threading
 
 [<AllowNullLiteral>]
 [<DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)>]
 type Component (render: IComponentContext -> IView) as this =
     inherit ComponentBase ()
 
     override this.Render ctx =
-        render ctx
-
-type Component with
-
-    static member create(key: string, render: IComponentContext -> IView) : IView<Component> =
-        { View.ViewType = typeof<Component>
-          View.ViewKey = ValueSome key
-          View.Attrs = list.Empty
-          View.Outlet = ValueNone
-          View.ConstructorArgs = [| render :> obj |] }
-        :> IView<Component>
+        render ctx

src/Avalonia.FuncUI/Components/Lib/Lib.Common.fs

@@ -2,6 +2,7 @@ namespace Avalonia.FuncUI
 
 open System
 open System.Collections.Generic
+open Microsoft.FSharp.Core
 
 [<RequireQualifiedAccess>]
 module internal ComponentHelpers =
@@ -38,3 +39,32 @@ module internal CommonExtensions =
     type Guid with
         member this.StringValue with get () = this.ToString()
         static member Unique with get () = Guid.NewGuid()
+
+
+[<RequireQualifiedAccess>]
+module internal RenderFunctionAnalysis =
+    open System
+    open System.Reflection
+    open System.Collections.Concurrent
+
+    let internal cache = ConcurrentDictionary<Type, bool>()
+
+    let private flags =
+        BindingFlags.Instance |||
+        BindingFlags.NonPublic |||
+        BindingFlags.Public
+
+    let capturesState (func : obj) : bool =
+        let type' = func.GetType()
+
+        let hasValue, value = cache.TryGetValue type'
+
+        match hasValue with
+        | true -> value
+        | false ->
+            let capturesState =
+                type'.GetConstructors(flags)
+                |> Array.map (fun info -> info.GetParameters().Length)
+                |> Array.exists (fun parameterLength -> parameterLength > 0)
+
+            cache.AddOrUpdate(type', capturesState, (fun identifier lastValue -> capturesState))

src/Avalonia.FuncUI/DSL/Component.fs

@@ -0,0 +1,18 @@
+[<AutoOpen>]
+module Avalonia.FuncUI.DSL.__ComponentExtensions
+
+open Avalonia.FuncUI
+open Avalonia.FuncUI.Builder
+open Avalonia.FuncUI.Types
+
+type Component with
+
+    static member create(key: string, render: IComponentContext -> IView) : IView<ComponentBase> =
+        { View.ViewType = typeof<Component>
+          View.ViewKey = ValueSome key
+          View.Attrs = [
+            //Component.renderFunction render
+          ]
+          View.Outlet = ValueNone
+          View.ConstructorArgs = [| render :> obj |] }
+        :> IView<ComponentBase>

src/Avalonia.FuncUI/Experimental/Experimental.ClosureComponent.fs

@@ -0,0 +1,79 @@
+namespace Avalonia.FuncUI.Experimental
+
+open System
+open System.Diagnostics.CodeAnalysis
+open Avalonia
+open Avalonia.FuncUI
+open Avalonia.FuncUI.Types
+open Avalonia.FuncUI.Builder
+
+/// Component that works well with a render function that captures state.
+[<AllowNullLiteral>]
+[<DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)>]
+type ClosureComponent (render: IComponentContext -> IView) as this =
+    inherit ComponentBase ()
+
+    static let _RenderFunctionProperty =
+        AvaloniaProperty.RegisterDirect<ClosureComponent, IComponentContext -> IView>(
+            name = "RenderFunction",
+            getter = Func<ClosureComponent, IComponentContext -> IView>(_.RenderFunction),
+            setter = (fun this value -> this.RenderFunction <- value)
+        )
+
+    static do
+        let _ = _RenderFunctionProperty.Changed.AddClassHandler<ClosureComponent, IComponentContext -> IView>(fun this e ->
+            let capturesState = RenderFunctionAnalysis.capturesState(e.NewValue.Value)
+
+            if capturesState then
+                this.ForceRender()
+        )
+        ()
+
+    let mutable _renderFunction = render
+
+    static member RenderFunctionProperty = _RenderFunctionProperty
+
+    member this.RenderFunction
+        with get() = _renderFunction
+        and set(value) =
+            let oldValue = _renderFunction
+            _renderFunction <- value
+            let _ = this.RaisePropertyChanged(ClosureComponent.RenderFunctionProperty, oldValue, value)
+            ()
+
+    override this.Render ctx =
+        _renderFunction ctx
+
+
+
+[<AutoOpen>]
+module __ClosureComponentExtensions =
+
+    type ClosureComponent with
+
+        static member internal renderFunction<'t when 't :> ClosureComponent>(value: IComponentContext -> IView) : IAttr<'t> =
+            AttrBuilder<'t>.CreateProperty<IComponentContext -> IView>(ClosureComponent.RenderFunctionProperty, value, ValueNone)
+
+        static member create(key: string, render: IComponentContext -> IView) : IView<ClosureComponent> =
+            let view: View<ClosureComponent> =
+              { View.ViewType = typeof<ClosureComponent>
+                View.ViewKey = ValueSome key
+                View.Attrs = [
+                  ClosureComponent.renderFunction render
+                ]
+                View.Outlet = ValueNone
+                View.ConstructorArgs = [| render :> obj |] }
+
+            view :> IView<ClosureComponent>
+
+        static member create(render: IComponentContext -> IView) : IView<ClosureComponent> =
+            let view: View<ClosureComponent> =
+              { View.ViewType = typeof<ClosureComponent>
+                View.ViewKey = ValueNone
+                View.Attrs = [
+                  ClosureComponent.renderFunction render
+                ]
+                View.Outlet = ValueNone
+                View.ConstructorArgs = [| render :> obj |] }
+
+            view :> IView<ClosureComponent>

src/Avalonia.FuncUI/Experimental/Experimental.EnvironmentState.fs

@@ -68,17 +68,27 @@ module private EnvironmentStateConsumer =
             else
                 tryFindNext (ancestor, state)
 
+
 [<AutoOpen>]
-module __ContextExtensions_useEnvHook =
+module __Control_useEnvValue =
 
-    type IComponentContext with
+    type Control with
 
         member this.readEnvValue(state: EnvironmentState<'value>) : 'value =
-            match EnvironmentStateConsumer.tryFind (this.control, state), state.DefaultValue with
+            match EnvironmentStateConsumer.tryFind (this, state), state.DefaultValue with
             | ValueSome value, _ -> value
             | ValueNone, Some defaultValue -> defaultValue
             | ValueNone, None -> failwithf "No value provided for environment value '%s'" state.Name
 
+
+[<AutoOpen>]
+module __ContextExtensions_useEnvHook =
+
+    type IComponentContext with
+
+        member this.readEnvValue(state: EnvironmentState<'value>) : 'value =
+            this.control.readEnvValue(state)
+
         member this.useEnvState(state: EnvironmentState<IWritable<'value>>, ?renderOnChange: bool) : IWritable<'value> =
            this.usePassedLazy (
                obtainValue = (fun () -> this.readEnvValue(state)),

src/Avalonia.FuncUI/Library.fs

@@ -44,10 +44,10 @@ module internal Extensions =
                 let handler = EventHandler<'args>(fun _ e ->
                     observer.OnNext e
                 )
-                
+
                 // subscribe to event changes so they can be pushed to subscribers
                 this.AddDisposableHandler(routedEvent, handler, routedEvent.RoutingStrategies)
             )
-            
+
             { new IObservable<'args>
-              with member this.Subscribe(observer: IObserver<'args>) = sub.Invoke(observer) }
+              with member this.Subscribe(observer: IObserver<'args>) = sub.Invoke(observer) }

src/Examples/Component Examples/Examples.TodoApp/ModalHost.fs

@@ -102,7 +102,4 @@ module __ContextExtensions_useModal =
     type IComponentContext with
 
         member this.useModalState() : ModalHostState =
-            this.readEnvValue ModalHost.State
-
-
-
+            this.readEnvValue ModalHost.State

src/Examples/Examples.ComponentPlayground/Examples.ComponentPlayground.fsproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <AvaloniaResource Include="**\*.xaml" />
+        <AvaloniaResource Include="Assets\*" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <Compile Include="Program.fs" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Avalonia.Desktop" Version="$(AvaloniaVersion)" />
+        <PackageReference Include="Avalonia.Themes.Fluent" Version="$(AvaloniaVersion)" />
+        <ProjectReference Include="..\..\Avalonia.FuncUI.Elmish\Avalonia.FuncUI.Elmish.fsproj" />
+        <ProjectReference Include="..\..\Avalonia.FuncUI\Avalonia.FuncUI.fsproj" />
+    </ItemGroup>
+
+</Project>