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2020 WPF 取经之路第10天 - MahApps 某些设计

时间：2020年04月16日 | 作者 : aaronyang | 分类 : WPF | 浏览: 1512次 | 评论 0 人

迁移完成了

DEMO1 附加属性的额外设计

由于wpf自带的控件很多依赖属性没有，为了不继承控件

可以采用附加属性。

比如ListBoxItem,TreeViewItem都有选中并且激活状态，设置背景色，字体色，禁用时候颜色，这就3个属性了。

  /// <summary>
        /// Gets or sets the background brush which will be used for the active selected item (if the keyboard focus is within).
        /// </summary>
        public static readonly DependencyProperty ActiveSelectionBackgroundBrushProperty
            = DependencyProperty.RegisterAttached("ActiveSelectionBackgroundBrush",
                                                  typeof(Brush),
                                                  typeof(ItemHelper),
                                                  new FrameworkPropertyMetadata(default(Brush), FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.Inherits));

        /// <summary>
        /// Gets the brush the background brush which will be used for the active selected item (if the keyboard focus is within).
        /// </summary>
        [Category(AppName.MahApps)]
        [AttachedPropertyBrowsableForType(typeof(ListBoxItem))]
        [AttachedPropertyBrowsableForType(typeof(TreeViewItem))]
        public static Brush GetActiveSelectionBackgroundBrush(UIElement element)
        {
            return (Brush)element.GetValue(ActiveSelectionBackgroundBrushProperty);
        }

        /// <summary>
        /// Sets the brush the background brush which will be used for the active selected item (if the keyboard focus is within).
        /// </summary>
        [Category(AppName.MahApps)]
        [AttachedPropertyBrowsableForType(typeof(ListBoxItem))]
        [AttachedPropertyBrowsableForType(typeof(TreeViewItem))]
        public static void SetActiveSelectionBackgroundBrush(UIElement element, Brush value)
        {
            element.SetValue(ActiveSelectionBackgroundBrushProperty, value);
        }

这里有个知识点

[AttachedPropertyBrowsableForType(typeof(TreeViewItem))]

可以让vs的属性设计器，那里列出来，感觉对xaml更友好

同样知识点2

new FrameworkPropertyMetadata(default(Brush), FrameworkPropertyMetadataOptions.AffectsRender | FrameworkPropertyMetadataOptions.Inherits));

这里的Options设置

当然还有

new UIPropertyMetadata(Brushes.White));

当然你还可以附加 Style类型的属性，这样可以暴露接口给使用者

new FrameworkPropertyMetadata(

new CornerRadius(),

FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender));

还有

new FrameworkPropertyMetadata(CharacterCasing.Normal, FrameworkPropertyMetadataOptions.AffectsMeasure),

new ValidateValueCallback(value => CharacterCasing.Normal <= (CharacterCasing)value && (CharacterCasing)value <= CharacterCasing.Upper));

      public static readonly DependencyProperty IsHiddenProperty
            = DependencyProperty.RegisterAttached(
                "IsHidden",
                typeof(bool?),
                typeof(VisibilityHelper),
                new FrameworkPropertyMetadata(default(bool?),
                    FrameworkPropertyMetadataOptions.AffectsArrange | FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsRender,
                    IsHiddenChangedCallback));

        private static void IsHiddenChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var fe = d as FrameworkElement;
            if (fe == null)
                return;

            fe.Visibility = ((bool?)e.NewValue) == true
                ? Visibility.Hidden
                : Visibility.Visible;
        }

发现个invoke封装的代码

using System;
using System.Windows;
using System.Windows.Threading;
using JetBrains.Annotations;

namespace MahApps.Metro.Controls
{
    public static class Extensions
    {
        public static T Invoke<T>([NotNull] this DispatcherObject dispatcherObject, [NotNull] Func<T> func)
        {
            if (dispatcherObject == null)
            {
                throw new ArgumentNullException(nameof(dispatcherObject));
            }
            if (func == null)
            {
                throw new ArgumentNullException(nameof(func));
            }
            if (dispatcherObject.Dispatcher.CheckAccess())
            {
                return func();
            }
            else
            {
                return (T)dispatcherObject.Dispatcher.Invoke(new Func<T>(func));
            }
        }

        public static void Invoke([NotNull] this DispatcherObject dispatcherObject, [NotNull] Action invokeAction)
        {
            if (dispatcherObject == null)
            {
                throw new ArgumentNullException(nameof(dispatcherObject));
            }
            if (invokeAction == null)
            {
                throw new ArgumentNullException(nameof(invokeAction));
            }
            if (dispatcherObject.Dispatcher.CheckAccess())
            {
                invokeAction();
            }
            else
            {
                dispatcherObject.Dispatcher.Invoke(invokeAction);
            }
        }

        /// <summary> 
        ///   Executes the specified action asynchronously with the DispatcherPriority.Background on the thread that the Dispatcher was created on.
        /// </summary>
        /// <param name="dispatcherObject">The dispatcher object where the action runs.</param>
        /// <param name="invokeAction">An action that takes no parameters.</param>
        /// <param name="priority">The dispatcher priority.</param> 
        public static void BeginInvoke([NotNull] this DispatcherObject dispatcherObject, [NotNull] Action invokeAction, DispatcherPriority priority = DispatcherPriority.Background)
        {
            if (dispatcherObject == null)
            {
                throw new ArgumentNullException(nameof(dispatcherObject));
            }
            if (invokeAction == null)
            {
                throw new ArgumentNullException(nameof(invokeAction));
            }
            dispatcherObject.Dispatcher.BeginInvoke(priority, invokeAction);
        }

        public static void BeginInvoke<T>([NotNull] this T dispatcherObject, [NotNull] Action<T> invokeAction, DispatcherPriority priority = DispatcherPriority.Background) where T: DispatcherObject
        {
            if (dispatcherObject == null)
            {
                throw new ArgumentNullException(nameof(dispatcherObject));
            }
            if (invokeAction == null)
            {
                throw new ArgumentNullException(nameof(invokeAction));
            }
            dispatcherObject.Dispatcher?.BeginInvoke(priority, new Action(() => invokeAction(dispatcherObject)));
        }

        /// <summary> 
        ///   Executes the specified action if the element is loaded or at the loaded event if it's not loaded.
        /// </summary>
        /// <param name="element">The element where the action should be run.</param>
        /// <param name="invokeAction">An action that takes no parameters.</param>
        public static void ExecuteWhenLoaded([NotNull] this FrameworkElement element, [NotNull] Action invokeAction)
        {
            if (element.IsLoaded)
            {
                element.Invoke(invokeAction);
            }
            else
            {
                RoutedEventHandler handler = null;
                handler = (o, a) =>
                    {
                        element.Loaded -= handler;
                        element.Invoke(invokeAction);
                    };

                element.Loaded += handler;
            }
        }
    }
}

自己把NotNull删掉

测试一个集合ReadOnlyObservableCollection

   static MainWindow()
        {
            baseColorsInternal = new ObservableCollection<string>() { "123", "456" };
            baseColors = new ReadOnlyObservableCollection<string>(baseColorsInternal);
        }
        private static readonly ObservableCollection<string> baseColorsInternal;
        private static readonly ReadOnlyObservableCollection<string> baseColors;
        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            baseColorsInternal[0] = "789";
            MessageBox.Show(baseColors[0]);
        }

答案是 789

说明是引用类型的

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