maui-linux/Handlers/NavigationPageHandler.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.Maui.Handlers;
using Microsoft.Maui.Graphics;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Platform;
using SkiaSharp;

namespace Microsoft.Maui.Platform.Linux.Handlers;

/// <summary>
/// Handler for NavigationPage on Linux using Skia rendering.
/// </summary>
public partial class NavigationPageHandler : ViewHandler<NavigationPage, SkiaNavigationPage>
{
    public static IPropertyMapper<NavigationPage, NavigationPageHandler> Mapper =
        new PropertyMapper<NavigationPage, NavigationPageHandler>(ViewHandler.ViewMapper)
        {
            [nameof(NavigationPage.BarBackgroundColor)] = MapBarBackgroundColor,
            [nameof(NavigationPage.BarBackground)] = MapBarBackground,
            [nameof(NavigationPage.BarTextColor)] = MapBarTextColor,
            [nameof(IView.Background)] = MapBackground,
        };

    public static CommandMapper<NavigationPage, NavigationPageHandler> CommandMapper =
        new(ViewHandler.ViewCommandMapper)
        {
            [nameof(IStackNavigationView.RequestNavigation)] = MapRequestNavigation,
        };

    public NavigationPageHandler() : base(Mapper, CommandMapper)
    {
    }

    public NavigationPageHandler(IPropertyMapper? mapper, CommandMapper? commandMapper = null)
        : base(mapper ?? Mapper, commandMapper ?? CommandMapper)
    {
    }

    protected override SkiaNavigationPage CreatePlatformView()
    {
        return new SkiaNavigationPage();
    }

    protected override void ConnectHandler(SkiaNavigationPage platformView)
    {
        base.ConnectHandler(platformView);
        platformView.Pushed += OnPushed;
        platformView.Popped += OnPopped;
        platformView.PoppedToRoot += OnPoppedToRoot;

        // Set initial root page if exists
        if (VirtualView.CurrentPage != null)
        {
            SetupInitialPage();
        }
    }

    protected override void DisconnectHandler(SkiaNavigationPage platformView)
    {
        platformView.Pushed -= OnPushed;
        platformView.Popped -= OnPopped;
        platformView.PoppedToRoot -= OnPoppedToRoot;
        base.DisconnectHandler(platformView);
    }

    private void SetupInitialPage()
    {
        var currentPage = VirtualView.CurrentPage;
        if (currentPage?.Handler?.PlatformView is SkiaPage skiaPage)
        {
            PlatformView.SetRootPage(skiaPage);
        }
    }

    private void OnPushed(object? sender, NavigationEventArgs e)
    {
        // Navigation was completed on platform side
    }

    private void OnPopped(object? sender, NavigationEventArgs e)
    {
        // Sync back to virtual view if needed
    }

    private void OnPoppedToRoot(object? sender, NavigationEventArgs e)
    {
        // Navigation was reset
    }

    public static void MapBarBackgroundColor(NavigationPageHandler handler, NavigationPage navigationPage)
    {
        if (handler.PlatformView is null) return;

        if (navigationPage.BarBackgroundColor is not null)
        {
            handler.PlatformView.BarBackgroundColor = navigationPage.BarBackgroundColor.ToSKColor();
        }
    }

    public static void MapBarBackground(NavigationPageHandler handler, NavigationPage navigationPage)
    {
        if (handler.PlatformView is null) return;

        if (navigationPage.BarBackground is SolidColorBrush solidBrush)
        {
            handler.PlatformView.BarBackgroundColor = solidBrush.Color.ToSKColor();
        }
    }

    public static void MapBarTextColor(NavigationPageHandler handler, NavigationPage navigationPage)
    {
        if (handler.PlatformView is null) return;

        if (navigationPage.BarTextColor is not null)
        {
            handler.PlatformView.BarTextColor = navigationPage.BarTextColor.ToSKColor();
        }
    }

    public static void MapBackground(NavigationPageHandler handler, NavigationPage navigationPage)
    {
        if (handler.PlatformView is null) return;

        if (navigationPage.Background is SolidColorBrush solidBrush)
        {
            handler.PlatformView.BackgroundColor = solidBrush.Color.ToSKColor();
        }
    }

    public static void MapRequestNavigation(NavigationPageHandler handler, NavigationPage navigationPage, object? args)
    {
        if (handler.PlatformView is null || args is not NavigationRequest request)
            return;

        // Handle navigation request
        foreach (var page in request.NavigationStack)
        {
            if (page.Handler?.PlatformView is SkiaPage skiaPage)
            {
                if (handler.PlatformView.StackDepth == 0)
                {
                    handler.PlatformView.SetRootPage(skiaPage);
                }
                else
                {
                    handler.PlatformView.Push(skiaPage, request.Animated);
                }
            }
        }
    }
}