|  | 
|  | 1 | +using System; | 
|  | 2 | +using System.Linq; | 
|  | 3 | +using Windows.Foundation.Collections; | 
|  | 4 | +using Windows.UI.Xaml.Markup; | 
|  | 5 | +using Microsoft.UI.Xaml; | 
|  | 6 | +using Microsoft.UI.Xaml.Data; | 
|  | 7 | +using Microsoft.UI.Xaml.Media; | 
|  | 8 | + | 
|  | 9 | +namespace Coder.Desktop.App.Converters; | 
|  | 10 | + | 
|  | 11 | +// This file uses manual DependencyProperty properties rather than | 
|  | 12 | +// DependencyPropertyGenerator since it doesn't seem to work properly with | 
|  | 13 | +// generics. | 
|  | 14 | + | 
|  | 15 | +/// <summary> | 
|  | 16 | +///     An item in a DependencyObjectSelector. Each item has a key and a value. | 
|  | 17 | +///     The default item in a DependencyObjectSelector will be the only item | 
|  | 18 | +///     with a null key. | 
|  | 19 | +/// </summary> | 
|  | 20 | +/// <typeparam name="TK">Key type</typeparam> | 
|  | 21 | +/// <typeparam name="TV">Value type</typeparam> | 
|  | 22 | +public class DependencyObjectSelectorItem<TK, TV> : DependencyObject | 
|  | 23 | +    where TK : IEquatable<TK> | 
|  | 24 | +{ | 
|  | 25 | +    public static readonly DependencyProperty KeyProperty = | 
|  | 26 | +        DependencyProperty.Register(nameof(Key), | 
|  | 27 | +            typeof(TK?), | 
|  | 28 | +            typeof(DependencyObjectSelectorItem<TK, TV>), | 
|  | 29 | +            new PropertyMetadata(null)); | 
|  | 30 | + | 
|  | 31 | +    public static readonly DependencyProperty ValueProperty = | 
|  | 32 | +        DependencyProperty.Register(nameof(Value), | 
|  | 33 | +            typeof(TV?), | 
|  | 34 | +            typeof(DependencyObjectSelectorItem<TK, TV>), | 
|  | 35 | +            new PropertyMetadata(null)); | 
|  | 36 | + | 
|  | 37 | +    public TK? Key | 
|  | 38 | +    { | 
|  | 39 | +        get => (TK?)GetValue(KeyProperty); | 
|  | 40 | +        set => SetValue(KeyProperty, value); | 
|  | 41 | +    } | 
|  | 42 | + | 
|  | 43 | +    public TV? Value | 
|  | 44 | +    { | 
|  | 45 | +        get => (TV?)GetValue(ValueProperty); | 
|  | 46 | +        set => SetValue(ValueProperty, value); | 
|  | 47 | +    } | 
|  | 48 | +} | 
|  | 49 | + | 
|  | 50 | +/// <summary> | 
|  | 51 | +///     Allows selecting between multiple value references based on a selected | 
|  | 52 | +///     key. This allows for dynamic mapping of model values to other objects. | 
|  | 53 | +///     The main use case is for selecting between other bound values, which | 
|  | 54 | +///     you cannot do with a simple ValueConverter. | 
|  | 55 | +/// </summary> | 
|  | 56 | +/// <typeparam name="TK">Key type</typeparam> | 
|  | 57 | +/// <typeparam name="TV">Value type</typeparam> | 
|  | 58 | +[ContentProperty(Name = nameof(References))] | 
|  | 59 | +public class DependencyObjectSelector<TK, TV> : DependencyObject | 
|  | 60 | +    where TK : IEquatable<TK> | 
|  | 61 | +{ | 
|  | 62 | +    public static readonly DependencyProperty ReferencesProperty = | 
|  | 63 | +        DependencyProperty.Register(nameof(References), | 
|  | 64 | +            typeof(DependencyObjectCollection), | 
|  | 65 | +            typeof(DependencyObjectSelector<TK, TV>), | 
|  | 66 | +            new PropertyMetadata(null, ReferencesPropertyChanged)); | 
|  | 67 | + | 
|  | 68 | +    public static readonly DependencyProperty SelectedKeyProperty = | 
|  | 69 | +        DependencyProperty.Register(nameof(SelectedKey), | 
|  | 70 | +            typeof(TK?), | 
|  | 71 | +            typeof(DependencyObjectSelector<TK, TV>), | 
|  | 72 | +            new PropertyMetadata(null, SelectedKeyPropertyChanged)); | 
|  | 73 | + | 
|  | 74 | +    public static readonly DependencyProperty SelectedObjectProperty = | 
|  | 75 | +        DependencyProperty.Register(nameof(SelectedObject), | 
|  | 76 | +            typeof(TV?), | 
|  | 77 | +            typeof(DependencyObjectSelector<TK, TV>), | 
|  | 78 | +            new PropertyMetadata(null)); | 
|  | 79 | + | 
|  | 80 | +    public DependencyObjectCollection? References | 
|  | 81 | +    { | 
|  | 82 | +        get => (DependencyObjectCollection?)GetValue(ReferencesProperty); | 
|  | 83 | +        set | 
|  | 84 | +        { | 
|  | 85 | +            // Ensure unique keys and that the values are DependencyObjectSelectorItem<K, V>. | 
|  | 86 | +            if (value != null) | 
|  | 87 | +            { | 
|  | 88 | +                var items = value.OfType<DependencyObjectSelectorItem<TK, TV>>().ToArray(); | 
|  | 89 | +                var keys = items.Select(i => i.Key).Distinct().ToArray(); | 
|  | 90 | +                if (keys.Length != value.Count) | 
|  | 91 | +                    throw new ArgumentException("ObservableCollection Keys must be unique."); | 
|  | 92 | +            } | 
|  | 93 | + | 
|  | 94 | +            SetValue(ReferencesProperty, value); | 
|  | 95 | +        } | 
|  | 96 | +    } | 
|  | 97 | + | 
|  | 98 | +    /// <summary> | 
|  | 99 | +    ///     The key of the selected item. This should be bound to a property on | 
|  | 100 | +    ///     the model. | 
|  | 101 | +    /// </summary> | 
|  | 102 | +    public TK? SelectedKey | 
|  | 103 | +    { | 
|  | 104 | +        get => (TK?)GetValue(SelectedKeyProperty); | 
|  | 105 | +        set => SetValue(SelectedKeyProperty, value); | 
|  | 106 | +    } | 
|  | 107 | + | 
|  | 108 | +    /// <summary> | 
|  | 109 | +    ///     The selected object. This can be read from to get the matching | 
|  | 110 | +    ///     object for the selected key. If the selected key doesn't match any | 
|  | 111 | +    ///     object, this will be the value of the null key. If there is no null | 
|  | 112 | +    ///     key, this will be null. | 
|  | 113 | +    /// </summary> | 
|  | 114 | +    public TV? SelectedObject | 
|  | 115 | +    { | 
|  | 116 | +        get => (TV?)GetValue(SelectedObjectProperty); | 
|  | 117 | +        set => SetValue(SelectedObjectProperty, value); | 
|  | 118 | +    } | 
|  | 119 | + | 
|  | 120 | +    public DependencyObjectSelector() | 
|  | 121 | +    { | 
|  | 122 | +        References = []; | 
|  | 123 | +    } | 
|  | 124 | + | 
|  | 125 | +    private void UpdateSelectedObject() | 
|  | 126 | +    { | 
|  | 127 | +        if (References != null) | 
|  | 128 | +        { | 
|  | 129 | +            // Look for a matching item a matching key, or fallback to the null | 
|  | 130 | +            // key. | 
|  | 131 | +            var references = References.OfType<DependencyObjectSelectorItem<TK, TV>>().ToArray(); | 
|  | 132 | +            var item = references | 
|  | 133 | +                           .FirstOrDefault(i => | 
|  | 134 | +                               (i.Key == null && SelectedKey == null) || | 
|  | 135 | +                               (i.Key != null && SelectedKey != null && i.Key!.Equals(SelectedKey!))) | 
|  | 136 | +                       ?? references.FirstOrDefault(i => i.Key == null); | 
|  | 137 | +            if (item is not null) | 
|  | 138 | +            { | 
|  | 139 | +                // Bind the SelectedObject property to the reference's Value. | 
|  | 140 | +                // If the underlying Value changes, it will propagate to the | 
|  | 141 | +                // SelectedObject. | 
|  | 142 | +                BindingOperations.SetBinding | 
|  | 143 | +                ( | 
|  | 144 | +                    this, | 
|  | 145 | +                    SelectedObjectProperty, | 
|  | 146 | +                    new Binding | 
|  | 147 | +                    { | 
|  | 148 | +                        Source = item, | 
|  | 149 | +                        Path = new PropertyPath(nameof(DependencyObjectSelectorItem<TK, TV>.Value)), | 
|  | 150 | +                    } | 
|  | 151 | +                ); | 
|  | 152 | +                return; | 
|  | 153 | +            } | 
|  | 154 | +        } | 
|  | 155 | + | 
|  | 156 | +        ClearValue(SelectedObjectProperty); | 
|  | 157 | +    } | 
|  | 158 | + | 
|  | 159 | +    // Called when the References property is replaced. | 
|  | 160 | +    private static void ReferencesPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) | 
|  | 161 | +    { | 
|  | 162 | +        var self = obj as DependencyObjectSelector<TK, TV>; | 
|  | 163 | +        if (self == null) return; | 
|  | 164 | +        var oldValue = args.OldValue as DependencyObjectCollection; | 
|  | 165 | +        if (oldValue != null) | 
|  | 166 | +            oldValue.VectorChanged -= self.OnVectorChangedReferences; | 
|  | 167 | +        var newValue = args.NewValue as DependencyObjectCollection; | 
|  | 168 | +        if (newValue != null) | 
|  | 169 | +            newValue.VectorChanged += self.OnVectorChangedReferences; | 
|  | 170 | +    } | 
|  | 171 | + | 
|  | 172 | +    // Called when the References collection changes without being replaced. | 
|  | 173 | +    private void OnVectorChangedReferences(IObservableVector<DependencyObject> sender, IVectorChangedEventArgs args) | 
|  | 174 | +    { | 
|  | 175 | +        UpdateSelectedObject(); | 
|  | 176 | +    } | 
|  | 177 | + | 
|  | 178 | +    // Called when SelectedKey changes. | 
|  | 179 | +    private static void SelectedKeyPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) | 
|  | 180 | +    { | 
|  | 181 | +        var self = obj as DependencyObjectSelector<TK, TV>; | 
|  | 182 | +        self?.UpdateSelectedObject(); | 
|  | 183 | +    } | 
|  | 184 | +} | 
|  | 185 | + | 
|  | 186 | +public sealed class StringToBrushSelectorItem : DependencyObjectSelectorItem<string, Brush>; | 
|  | 187 | + | 
|  | 188 | +public sealed class StringToBrushSelector : DependencyObjectSelector<string, Brush>; | 
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