85 lines
2.5 KiB
C#
85 lines
2.5 KiB
C#
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using System.Windows;
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using System.Windows.Controls;
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namespace PCL;
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public class MyVirtualizingElement<T> : FrameworkElement where T : FrameworkElement
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{
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private readonly Func<T> _initializer;
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public MyVirtualizingElement(Func<T> initializer)
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{
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_initializer = initializer;
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this.EnableLazyLoad(() => Init());
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}
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/// <summary>
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/// 实例化此控件。
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/// </summary>
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public T Init()
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{
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var element = _initializer();
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if (Parent is not null)
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{
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if (Parent is not Panel)
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throw new Exception("MyVirtualizingElement 的父级必须是一个 Panel");
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var parentPanel = (Panel)Parent;
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var currentIndex = parentPanel.Children.IndexOf(this);
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parentPanel.Children.RemoveAt(currentIndex);
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parentPanel.Children.Insert(currentIndex, element);
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}
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return element;
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}
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public static implicit operator T(MyVirtualizingElement<T> virtualized)
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{
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return virtualized.Init();
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}
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}
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// 非泛型形式
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public class MyVirtualizingElement : FrameworkElement
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{
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private readonly Func<FrameworkElement> _initializer;
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public MyVirtualizingElement(Func<FrameworkElement> initializer)
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{
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_initializer = initializer;
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this.EnableLazyLoad(() => Init());
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}
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/// <summary>
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/// 实例化此控件。
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/// </summary>
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public FrameworkElement Init()
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{
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var element = _initializer();
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if (Parent is not null)
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{
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if (Parent is not Panel)
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throw new Exception("MyVirtualizingElement 的父级必须是一个 Panel");
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var parentPanel = (Panel)Parent;
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var currentIndex = parentPanel.Children.IndexOf(this);
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parentPanel.Children.RemoveAt(currentIndex);
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parentPanel.Children.Insert(currentIndex, element);
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}
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return element;
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}
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/// <summary>
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/// 获取实例化后的控件。
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/// 如果该控件没有实例化，则会立即实例化。
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/// 如果类型错误，则返回原值。
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/// </summary>
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public static FrameworkElement TryInit(FrameworkElement element)
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{
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if (typeof(MyVirtualizingElement<>).IsInstanceOfGenericType(element))
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{
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var method = element.GetType().GetMethod("Init", Type.EmptyTypes);
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return (FrameworkElement)method.Invoke(element, null);
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}
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return element is MyVirtualizingElement ? ((MyVirtualizingElement)element).Init() : element;
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}
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}
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