HyperlinkWidget.cs

using System.Drawing;
using Gondwana.Drawing.Direct;
using Gondwana.Input.Keyboard;
using Gondwana.Rendering;
using Gondwana.Rendering.Views;
using Gondwana.Scenes;
using SkiaSharp;
 
namespace Gondwana.Widgets.Controls;

public sealed class HyperlinkWidget : WidgetBase
{
    private readonly IExternalUriLauncher _uriLauncher;
    private readonly SKColor _normalColor = new(80, 150, 255);
    private readonly SKColor _hoverColor = new(125, 185, 255);
 
    #region events

    public event Action<Uri>? LinkOpened;

    public event Action<Uri, Exception>? LinkOpenFailed;
 
    #endregion
 
    #region constructors

    public HyperlinkWidget(IExternalUriLauncher uriLauncher,
                           RenderSurfaceHostBase renderSurfaceHost,
                           View view,
                           Rectangle bounds,
                           string text,
                           Uri navigateUri,
                           string? nickname = null)
        : base(renderSurfaceHost, DirectDrawingMode.View, bounds.Location, nickname)
    {
        ArgumentNullException.ThrowIfNull(uriLauncher);
        ArgumentNullException.ThrowIfNull(view);
        ArgumentNullException.ThrowIfNull(navigateUri);
 
        if (!navigateUri.IsAbsoluteUri)
            throw new ArgumentException("The URI must be absolute.", nameof(navigateUri));
 
        _uriLauncher = uriLauncher;
        NavigateUri = navigateUri;
        Label = CreateLabel(renderSurfaceHost, view, bounds, text);
 
        Add(Label);
        CompleteInitialization();
    }

    public HyperlinkWidget(IExternalUriLauncher uriLauncher,
                           RenderSurfaceHostBase renderSurfaceHost,
                           SceneLayer sceneLayer,
                           Rectangle bounds,
                           string text,
                           Uri navigateUri,
                           string? nickname = null)
        : base(renderSurfaceHost, DirectDrawingMode.SceneLayer, bounds.Location, nickname)
    {
        ArgumentNullException.ThrowIfNull(uriLauncher);
        ArgumentNullException.ThrowIfNull(sceneLayer);
        ArgumentNullException.ThrowIfNull(navigateUri);
 
        _uriLauncher = uriLauncher;
        NavigateUri = navigateUri;
 
        Label = CreateLabel(renderSurfaceHost, sceneLayer, bounds, text);
 
        Add(Label);
        CompleteInitialization();
    }
 
    #endregion constructors
 
    #region public properties

    public Uri NavigateUri { get; set; }

    public TextBlock Label { get; }
 
    #endregion public properties
 
    #region public methods

    public async ValueTask OpenAsync(CancellationToken cancellationToken = default)
    {
        if (!IsInputEnabled)
            return;
 
        Uri uri = NavigateUri;
 
        try
        {
            await _uriLauncher.OpenAsync(uri, cancellationToken);
            LinkOpened?.Invoke(uri);
        }
        catch (Exception ex)
        {
            LinkOpenFailed?.Invoke(uri, ex);
        }
    }
 
    #endregion public methods
 
    #region protected methods

    protected override void OnPointerEnter(WidgetPointerEventArgs args)
    {
        base.OnPointerEnter(args);
        Label.SetColors(_hoverColor, SKColors.Transparent);
    }

    protected override void OnPointerLeave(WidgetPointerEventArgs args)
    {
        base.OnPointerLeave(args);
        Label.SetColors(_normalColor, SKColors.Transparent);
    }

    protected override void OnPointerClick(WidgetPointerEventArgs args)
    {
        base.OnPointerClick(args);
 
        if (!args.IsPrimaryButton)
            return;
 
        args.Handled = true;
        _ = OpenAsync();
    }

    protected override void OnKeyboardInput(WidgetKeyboardEventArgs args)
    {
        base.OnKeyboardInput(args);
 
        if (args.KeyAction != KeyAction.Pressed)
            return;
 
        // Standard Enter and Space virtual-key values.
        if (args.Key is not 13 and not 32)
            return;
 
        args.Handled = true;
        _ = OpenAsync();
    }
 
    #endregion protected methods
 
    #region private methods
 
    private void CompleteInitialization()
    {
        CanReceiveFocus = true;
        IsKeyboardInputEnabled = true;
    }
 
    private TextBlock CreateLabel(RenderSurfaceHostBase host,
                                  View view,
                                  Rectangle bounds,
                                  string text)
    {
        return new TextBlock(host, view, bounds)
            .SetText(text)
            .SetFont(SKTypeface.Default, 16f, minSize: 10f)
            .SetColors(_normalColor, SKColors.Transparent)
            .SetAlignment(SKTextAlign.Left, TextBlock.VerticalAlign.Center)
            .EnableWrapping(false);
    }
 
    private TextBlock CreateLabel(RenderSurfaceHostBase host,
                                  SceneLayer layer,
                                  Rectangle bounds,
                                  string text)
    {
        return new TextBlock(host, layer, view: null, worldBounds: bounds)
            .SetText(text)
            .SetFont(SKTypeface.Default, 16f, minSize: 10f)
            .SetColors(_normalColor, SKColors.Transparent)
            .SetAlignment(SKTextAlign.Left, TextBlock.VerticalAlign.Center)
            .EnableWrapping(false);
    }
 
    #endregion private methods
}