Navigation sample with components

Fabulous.MauiControls.sln

@@ -53,6 +53,8 @@ Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "BasicNavigation", "samples\
 EndProject
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "NavigationPath", "samples\Navigation\NavigationPath\NavigationPath.fsproj", "{5B3F6C4E-82CF-442F-BFB4-216C1CD85700}"
 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "ComponentNavigation", "samples\Navigation\ComponentNavigation\ComponentNavigation.fsproj", "{66532A61-1BB8-4BD1-A281-A160ABB0EFE7}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -128,6 +130,10 @@ Global
 		{5B3F6C4E-82CF-442F-BFB4-216C1CD85700}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5B3F6C4E-82CF-442F-BFB4-216C1CD85700}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5B3F6C4E-82CF-442F-BFB4-216C1CD85700}.Release|Any CPU.Build.0 = Release|Any CPU
+		{66532A61-1BB8-4BD1-A281-A160ABB0EFE7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{66532A61-1BB8-4BD1-A281-A160ABB0EFE7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{66532A61-1BB8-4BD1-A281-A160ABB0EFE7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{66532A61-1BB8-4BD1-A281-A160ABB0EFE7}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{67FB01A1-1A3E-4A3B-83DC-7D63B56FB1A1} = {35A6823C-8312-4F92-818A-5117BB31A569}
@@ -146,5 +152,6 @@ Global
 		{3A3581BD-4228-49B0-84D5-AF39D620BA34} = {87C8E9E8-497E-46DB-90FE-4402E0CB230A}
 		{CE61493B-86CC-49CE-9443-F25F1ECB15C9} = {3A3581BD-4228-49B0-84D5-AF39D620BA34}
 		{5B3F6C4E-82CF-442F-BFB4-216C1CD85700} = {3A3581BD-4228-49B0-84D5-AF39D620BA34}
+		{66532A61-1BB8-4BD1-A281-A160ABB0EFE7} = {3A3581BD-4228-49B0-84D5-AF39D620BA34}
 	EndGlobalSection
 EndGlobal

samples/Navigation/ComponentNavigation/AppMsg.fs

@@ -0,0 +1,17 @@
+namespace ComponentNavigation
+
+/// With each component runs in an isolated context, so we need a way to communicate between them.
+/// We define application-wide messages here, and a dispatcher to send and receive messages.
+[<RequireQualifiedAccess>]
+type AppMsg = | BackButtonPressed
+
+type IAppMessageDispatcher =
+    abstract Dispatched: IEvent<AppMsg>
+    abstract member Dispatch: AppMsg -> unit
+
+type AppMessageDispatcher() =
+    let dispatched = Event<AppMsg>()
+
+    interface IAppMessageDispatcher with
+        member _.Dispatched = dispatched.Publish
+        member _.Dispatch(msg) = dispatched.Trigger(msg)

samples/Navigation/ComponentNavigation/ComponentNavigation.fsproj

@@ -0,0 +1,107 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net8.0-android;net8.0-ios;net8.0-maccatalyst</TargetFrameworks>
+    <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net8.0-windows10.0.19041.0</TargetFrameworks>
+    <!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
+    <!-- <TargetFrameworks>$(TargetFrameworks);net7.0-tizen</TargetFrameworks> -->
+    <OutputType>Exe</OutputType>
+    <RootNamespace>ComponentNavigation</RootNamespace>
+    <UseMaui>true</UseMaui>
+    <SingleProject>true</SingleProject>
+    <EnableDefaultItems>false</EnableDefaultItems>
+
+    <!-- Display name -->
+    <ApplicationTitle>ComponentNavigation</ApplicationTitle>
+
+    <!-- App Identifier -->
+    <ApplicationId>org.fabulous.maui.componentnavigation</ApplicationId>
+    <ApplicationIdGuid>9abd223e-09e7-4649-b22b-7395cb4724e1</ApplicationIdGuid>
+
+    <!-- Versions -->
+    <ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
+    <ApplicationVersion>1</ApplicationVersion>
+
+    <TargetPlatformIdentifier Condition=" $(TargetPlatformIdentifier) == '' ">$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</TargetPlatformIdentifier>
+
+    <SupportedOSPlatformVersion Condition="$(TargetPlatformIdentifier) == 'ios'">14.2</SupportedOSPlatformVersion>
+    <SupportedOSPlatformVersion Condition="$(TargetPlatformIdentifier) == 'maccatalyst'">14.0</SupportedOSPlatformVersion>
+    <SupportedOSPlatformVersion Condition="$(TargetPlatformIdentifier) == 'android'">21.0</SupportedOSPlatformVersion>
+    <SupportedOSPlatformVersion Condition="$(TargetPlatformIdentifier) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
+    <TargetPlatformMinVersion Condition="$(TargetPlatformIdentifier) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
+    <SupportedOSPlatformVersion Condition="$(TargetPlatformIdentifier) == 'tizen'">6.5</SupportedOSPlatformVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="AppMsg.fs" />
+    <Compile Include="Navigation.fs" />
+    <Compile Include="PageA.fs" />
+    <Compile Include="PageB.fs" />
+    <Compile Include="PageC.fs" />
+    <Compile Include="Sample.fs" />
+    <Compile Include="MauiProgram.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <!-- App Icon -->
+    <MauiIcon Include="Resources\AppIcon\appicon.svg" ForegroundFile="Resources\AppIcon\appiconfg.svg" Color="#512BD4" />
+
+    <!-- Custom Fonts -->
+    <MauiFont Include="Resources\Fonts\*" />
+
+    <!-- Images -->
+    <MauiImage Include="Resources\Images\*" />
+    <MauiImage Update="Resources\Images\dotnet_bot.svg" BaseSize="168,208" />
+
+    <!-- Raw Assets (also remove the "Resources\Raw" prefix) -->
+    <MauiAsset Include="Resources\Raw\*" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+
+    <!-- Splash Screen -->
+    <MauiSplashScreen Include="Resources\Splash\splash.svg" Color="#512BD4" BaseSize="128,128" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$(TargetPlatformIdentifier) == 'android'">
+    <AndroidResource Include="$(AndroidProjectFolder)Resources/*/*" />
+    <AndroidResource Remove="$(AndroidProjectFolder)Resources/raw/.*" />
+    <AndroidResource Update="$(AndroidProjectFolder)Resources/raw/*" />
+    <AndroidAsset Include="$(AndroidProjectFolder)Assets/**/*" Exclude="$(AndroidProjectFolder)Assets/**/.*/**" />
+    <AndroidManifest Include="$(AndroidProjectFolder)AndroidManifest.xml" />
+    <Compile Include="$(AndroidProjectFolder)MainActivity.fs" />
+    <Compile Include="$(AndroidProjectFolder)MainApplication.fs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$(TargetPlatformIdentifier) == 'ios'">
+    <None Include="$(iOSProjectFolder)Info.plist" LogicalName="Info.plist" />
+    <Compile Include="$(iOSProjectFolder)AppDelegate.fs" />
+    <Compile Include="$(iOSProjectFolder)Program.fs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$(TargetPlatformIdentifier) == 'maccatalyst'">
+    <None Include="$(MacCatalystProjectFolder)Info.plist" LogicalName="Info.plist" />
+    <Compile Include="$(MacCatalystProjectFolder)AppDelegate.fs" />
+    <Compile Include="$(MacCatalystProjectFolder)Program.fs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$(TargetPlatformIdentifier) == 'windows'">
+    <Manifest Include="$(WindowsProjectFolder)app.manifest" />
+    <AppxManifest Include="$(WindowsProjectFolder)Package.appxmanifest" />
+    <Compile Include="$(WindowsProjectFolder)App.fs" />
+    <Compile Include="$(WindowsProjectFolder)Main.fs" />
+
+    <PackageReference Include="FSharp.Maui.WinUICompat" />
+  </ItemGroup>
+
+  <ItemGroup Condition="$(TargetPlatformIdentifier) == 'tizen'">
+    <TizenManifestFile Include="$(TizenProjectFolder)tizen-manifest.xml" />
+    <Compile Include="$(TizenProjectFolder)Main.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FSharp.Core" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\src\Fabulous.MauiControls\Fabulous.MauiControls.fsproj" />
+  </ItemGroup>
+
+</Project>

samples/Navigation/ComponentNavigation/MauiProgram.fs

@@ -0,0 +1,19 @@
+namespace ComponentNavigation
+
+open Microsoft.Maui.Hosting
+open Fabulous.Maui
+
+type MauiProgram =
+    static member CreateMauiApp() =
+        let nav = NavigationController()
+        let appMsgDispatcher = AppMessageDispatcher()
+
+        MauiApp
+            .CreateBuilder()
+            .UseFabulousApp(Sample.view nav appMsgDispatcher)
+            .ConfigureFonts(fun fonts ->
+                fonts
+                    .AddFont("OpenSans-Regular.ttf", "OpenSansRegular")
+                    .AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold")
+                |> ignore)
+            .Build()

samples/Navigation/ComponentNavigation/Navigation.fs

@@ -0,0 +1,66 @@
+namespace ComponentNavigation
+
+open Fabulous
+
+/// This is the centerpiece of navigating through paths:
+/// A single enum regrouping all the navigation routes with their arguments
+[<RequireQualifiedAccess>]
+type NavigationRoute =
+    | PageA
+    | PageB of initialCount: int
+    | PageC of someArgs: string * stepCount: int
+
+/// The NavigationController is used to notify the intention to navigate to a new page (or go back).
+/// We listen to it in a Cmd that will dispatch a message to the root of the application to trigger the actual navigation.
+type NavigationController() =
+    let navigationRequested = Event<NavigationRoute>()
+    let backNavigationRequested = Event<unit>()
+
+    member this.NavigationRequested = navigationRequested.Publish
+    member this.BackNavigationRequested = backNavigationRequested.Publish
+
+    member this.NavigateTo(path: NavigationRoute) = navigationRequested.Trigger(path)
+
+    member this.NavigateBack() = backNavigationRequested.Trigger()
+
+/// The Navigation module is a set of helper functions that will wrap the call to NavigationController into a Cmd.
+/// We do that because navigation is a side-effect and we want to keep it in a Cmd.
+module Navigation =
+    let private navigateTo (nav: NavigationController) path : Cmd<'msg> = [ fun _ -> nav.NavigateTo(path) ]
+
+    let navigateBack (nav: NavigationController) : Cmd<'msg> = [ fun _ -> nav.NavigateBack() ]
+
+    let navigateToPageA nav = navigateTo nav NavigationRoute.PageA
+
+    let navigateToPageB nav initialCount =
+        navigateTo nav (NavigationRoute.PageB initialCount)
+
+    let navigateToPageC nav someArgs stepCount =
+        navigateTo nav (NavigationRoute.PageC(someArgs, stepCount))
+
+/// The NavigationStack represents the history of the navigation.
+/// This is a simple stack of pages that the app will use to remember and display the pages needed.
+type NavigationStack =
+    { BackStack: NavigationRoute list
+      CurrentPage: NavigationRoute
+      ForwardStack: NavigationRoute list }
+
+    static member Init(path: NavigationRoute) =
+        { BackStack = []
+          CurrentPage = path
+          ForwardStack = [] }
+
+    member this.Push(path: NavigationRoute) =
+        { BackStack = this.CurrentPage :: this.BackStack
+          CurrentPage = path
+          ForwardStack = [] }
+
+    member this.Pop() =
+        match this.BackStack with
+        | [] -> this
+        | head :: tail ->
+            { BackStack = tail
+              CurrentPage = head
+              ForwardStack = [] }
+
+    member this.UpdateCurrentPage(path: NavigationRoute) = { this with CurrentPage = path }

samples/Navigation/ComponentNavigation/PageA.fs

@@ -0,0 +1,75 @@
+namespace ComponentNavigation
+
+open Fabulous
+open Fabulous.Maui
+
+open type Fabulous.Maui.View
+
+/// Each page is "isolated". They have their own MVU loop and own types.
+/// The only dependency they receive from outside is the NavigationController, which is passed to the update function.
+module PageA =
+    type Model = { IsActive: bool; Count: int }
+
+    type Msg =
+        | Active
+        | Inactive
+        | Increment
+        | Decrement
+        | GoBack
+        | GoToPageB
+        | GoToPageC
+        | BackButtonPressed
+
+    /// Since the NavigationRoute.PageA doesn't take arguments, the init function excepts a unit parameter.
+    let init () =
+        { IsActive = false; Count = 0 }, Cmd.none
+
+    let update (nav: NavigationController) msg model =
+        match msg with
+        | Active -> { model with IsActive = true }, Cmd.none
+        | Inactive -> { model with IsActive = false }, Cmd.none
+        | Increment -> { model with Count = model.Count + 1 }, Cmd.none
+        | Decrement -> { model with Count = model.Count - 1 }, Cmd.none
+        | GoBack -> model, Navigation.navigateBack nav
+        | GoToPageB -> model, Navigation.navigateToPageB nav model.Count
+        | GoToPageC -> model, Navigation.navigateToPageC nav "Hello from Page A!" model.Count
+        | BackButtonPressed -> { model with Count = model.Count - 1 }, Cmd.none
+
+    let subscribe (appMsgDispatcher: IAppMessageDispatcher) model =
+        let localAppMsgSub dispatch =
+            appMsgDispatcher.Dispatched.Subscribe(fun msg ->
+                match msg with
+                | AppMsg.BackButtonPressed -> dispatch BackButtonPressed)
+
+        [ if model.IsActive then
+              [ nameof localAppMsgSub ], localAppMsgSub ]
+
+    let program nav appMsgDispatcher =
+        Program.statefulWithCmd init (update nav)
+        |> Program.withSubscription(subscribe appMsgDispatcher)
+
+    let view nav appMsgDispatcher =
+        Component(program nav appMsgDispatcher) {
+            let! model = Mvu.State
+
+            ContentPage(
+                Grid(coldefs = [ Star ], rowdefs = [ Star; Auto ]) {
+                    VStack() {
+                        Label($"Count: {model.Count}").centerTextHorizontal()
+
+                        Button("Increment", Increment)
+                        Button("Decrement", Decrement)
+                    }
+
+                    (VStack() {
+                        Button("Go back", GoBack)
+                        Button("Go to Page B", GoToPageB)
+                        Button("Go to Page C", GoToPageC)
+                    })
+                        .gridRow(1)
+                }
+            )
+                .title("Page A")
+                .onNavigatedTo(Active)
+                .onNavigatedFrom(Inactive)
+        }

samples/Navigation/ComponentNavigation/PageB.fs

@@ -0,0 +1,79 @@
+namespace ComponentNavigation
+
+open Fabulous
+open Fabulous.Maui
+
+open type Fabulous.Maui.View
+
+module PageB =
+    type Model =
+        { IsActive: bool
+          InitialCount: int
+          Count: int }
+
+    type Msg =
+        | Active
+        | Inactive
+        | Increment
+        | Decrement
+        | GoBack
+        | GoToPageA
+        | GoToPageC
+
+    /// Contrary to PageA, NavigationPath.PageB has a initialCount argument so the init function will receive it.
+    let init initialCount =
+        { IsActive = false
+          InitialCount = initialCount
+          Count = initialCount },
+        Cmd.none
+
+    let update (nav: NavigationController) msg model =
+        match msg with
+        | Active -> { model with IsActive = true }, Cmd.none
+        | Inactive -> { model with IsActive = false }, Cmd.none
+        | Increment -> { model with Count = model.Count + 1 }, Cmd.none
+        | Decrement -> { model with Count = model.Count - 1 }, Cmd.none
+        | GoBack -> model, Navigation.navigateBack nav
+        | GoToPageA -> model, Navigation.navigateToPageA nav
+        | GoToPageC -> model, Navigation.navigateToPageC nav "Hello from Page A!" model.Count
+
+    let subscribe (appMsgDispatcher: IAppMessageDispatcher) model =
+        let localAppMsgSub dispatch =
+            appMsgDispatcher.Dispatched.Subscribe(fun msg ->
+                match msg with
+                | AppMsg.BackButtonPressed -> dispatch GoBack)
+
+        [ if model.IsActive then
+              [ nameof localAppMsgSub ], localAppMsgSub ]
+
+    let program nav appMsgDispatcher =
+        Program.statefulWithCmd init (update nav)
+        |> Program.withSubscription(subscribe appMsgDispatcher)
+
+    let view nav appMsgDispatcher arg =
+        Component(program nav appMsgDispatcher, arg) {
+            let! model = Mvu.State
+
+            ContentPage(
+                Grid(coldefs = [ Star ], rowdefs = [ Star; Auto ]) {
+                    VStack() {
+                        Label($"Initial count: {model.InitialCount}")
+
+                        Label($"Count: {model.Count}").centerTextHorizontal()
+
+                        Button("Increment", Increment)
+                        Button("Decrement", Decrement)
+                    }
+
+                    (VStack() {
+                        Button("Go back", GoBack)
+                        Button("Go to Page A", GoToPageA)
+                        Button("Go to Page C", GoToPageC)
+                    })
+                        .gridRow(1)
+                }
+            )
+                .title("Page B")
+                .onNavigatedTo(Active)
+                .onNavigatedFrom(Inactive)
+        }