DeskCore/Dialog.cs

using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

namespace DeskCore;

/// <summary>Dialoge im Stil eines Windows-11-ContentDialogs.</summary>
public static class Dialog
{
    public static bool Confirm(Window owner, string title, string message, string primary = "OK", string? secondary = "Abbrechen") =>
        Show(owner, title, Text(message), primary, secondary, null);

    public static void Info(Window owner, string title, string message) =>
        Show(owner, title, Text(message), "OK", null, null);

    /// <summary>Eingabedialog. validate gibt eine Fehlermeldung oder null zurück.</summary>
    public static string? Prompt(Window owner, string title, string label, string initial, string primary, Func<string, string?> validate)
    {
        var box = new TextBox { Text = initial, Margin = new Thickness(0, 8, 0, 0) };
        var panel = new StackPanel();
        panel.Children.Add(Text(label, secondary: true));
        panel.Children.Add(box);
        var ok = Show(owner, title, panel, primary, "Abbrechen", () => validate(box.Text), box);
        return ok ? box.Text.Trim() : null;
    }

    public static TextBlock Text(string text, bool secondary = false) => new()
    {
        Text = text, TextWrapping = TextWrapping.Wrap, LineHeight = 20,
        Foreground = (Brush)Application.Current.Resources[secondary ? "TextSecondaryBrush" : "TextBrush"],
    };

    /// <summary>Allgemeiner Dialog mit beliebigem Inhalt. validate: Fehlermeldung oder null.</summary>
    public static bool Show(Window owner, string title, UIElement content, string primary, string? secondary,
        Func<string?>? validate, IInputElement? focus = null, double width = 448)
    {
        var res = Application.Current.Resources;

        var error = new TextBlock
        {
            Foreground = (Brush)res["DangerBrush"], FontSize = 12, Margin = new Thickness(0, 8, 0, 0),
            TextWrapping = TextWrapping.Wrap, Visibility = Visibility.Collapsed,
        };

        var body = new StackPanel { Margin = new Thickness(24, 22, 24, 24) };
        body.Children.Add(new TextBlock
        {
            Text = title, FontSize = 20, FontWeight = FontWeights.SemiBold, Margin = new Thickness(0, 0, 0, 12),
            FontFamily = (FontFamily)res["DisplayFont"], TextWrapping = TextWrapping.Wrap,
        });
        body.Children.Add(content);
        body.Children.Add(error);

        var ok = new Button { Content = primary, IsDefault = true, Style = (Style)res["AccentButton"] };
        var footer = new Grid { Margin = new Thickness(24) };
        footer.ColumnDefinitions.Add(new ColumnDefinition());
        footer.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(8) });
        footer.ColumnDefinitions.Add(new ColumnDefinition());
        if (secondary is not null)
        {
            var cancel = new Button { Content = secondary, IsCancel = true };
            Grid.SetColumn(cancel, 2);
            footer.Children.Add(cancel);
        }
        else Grid.SetColumn(ok, 2); // einzelner Button rechts, wie bei Windows 11
        footer.Children.Add(ok);

        var layout = new DockPanel();
        var footerBorder = new Border
        {
            Background = (Brush)res["DialogFooterBrush"], Child = footer,
            BorderBrush = (Brush)res["FlyoutStrokeBrush"], BorderThickness = new Thickness(0, 1, 0, 0),
            CornerRadius = new CornerRadius(0, 0, 8, 8),
        };
        DockPanel.SetDock(footerBorder, Dock.Bottom);
        layout.Children.Add(footerBorder);
        layout.Children.Add(new ScrollViewer { Content = body, VerticalScrollBarVisibility = ScrollBarVisibility.Auto, MaxHeight = 560 });

        var dlg = new Window
        {
            Owner = owner.IsVisible ? owner : null, Title = title, Width = width + 64, SizeToContent = SizeToContent.Height,
            WindowStyle = WindowStyle.None, AllowsTransparency = true, Background = Brushes.Transparent,
            ResizeMode = ResizeMode.NoResize, ShowInTaskbar = !owner.IsVisible, Topmost = !owner.IsVisible,
            WindowStartupLocation = owner.IsVisible ? WindowStartupLocation.CenterOwner : WindowStartupLocation.CenterScreen,
            FontFamily = (FontFamily)res["UiFont"], FontSize = 14,
            Foreground = (Brush)res["TextBrush"],
            Content = new Border
            {
                Margin = new Thickness(32), CornerRadius = new CornerRadius(8),
                Background = (Brush)res["LayerBrush"],
                BorderBrush = (Brush)res["FlyoutStrokeBrush"], BorderThickness = new Thickness(1),
                Effect = (System.Windows.Media.Effects.Effect)res["DialogShadow"], Child = layout,
            },
        };

        ok.Click += (_, _) =>
        {
            if (validate?.Invoke() is { } err)
            {
                error.Text = err;
                error.Visibility = Visibility.Visible;
                (focus as UIElement)?.Focus();
                return;
            }
            dlg.DialogResult = true;
        };
        if (focus is TextBox tb) tb.TextChanged += (_, _) => error.Visibility = Visibility.Collapsed;

        dlg.PreviewKeyDown += (_, e) => { if (e.Key == Key.Escape) dlg.Close(); };
        dlg.MouseLeftButtonDown += (_, e) => { if (e.ButtonState == MouseButtonState.Pressed) dlg.DragMove(); };
        dlg.Loaded += (_, _) =>
        {
            if (focus is TextBox t) { t.Focus(); t.SelectAll(); }
            else if (focus is UIElement u) u.Focus();
            else ok.Focus();
        };

        (owner as MainWindow)?.SetDimmed(true);
        try
        {
            return dlg.ShowDialog() == true;
        }
        finally
        {
            (owner as MainWindow)?.SetDimmed(false);
        }
    }
}