2.12.0

2025-12-27 02:48:47 +08:00
parent d6ba445e54
commit 085af160a1
78 changed files with 8426 additions and 4863 deletions
@@ -0,0 +1,70 @@
+Public Class MyVirtualizingElement(Of T As FrameworkElement)
+    Inherits FrameworkElement
+
+    Private Initializer As Func(Of T)
+    Public Sub New(Initializer As Func(Of T))
+        Me.Initializer = Initializer
+        OnFirstEnterScrollViewerViewport(AddressOf Init)
+    End Sub
+
+    ''' <summary>
+    ''' 实例化此控件。
+    ''' </summary>
+    Public Function Init() As T
+        Dim Element As T = Initializer()
+        If Parent IsNot Nothing Then
+            If TypeOf Parent IsNot Panel Then Throw New Exception("MyVirtualizingElement 的父级必须是一个 Panel")
+            Dim ParentPanel As Panel = Parent
+            Dim CurrentIndex As Integer = ParentPanel.Children.IndexOf(Me)
+            ParentPanel.Children.RemoveAt(CurrentIndex)
+            ParentPanel.Children.Insert(CurrentIndex, Element)
+        End If
+        Return Element
+    End Function
+    Public Shared Widening Operator CType(Virtualized As MyVirtualizingElement(Of T)) As T
+        Return Virtualized.Init()
+    End Operator
+
+End Class
+
+'非泛型形式
+Public Class MyVirtualizingElement
+    Inherits FrameworkElement
+
+    Private Initializer As Func(Of FrameworkElement)
+    Public Sub New(Initializer As Func(Of FrameworkElement))
+        Me.Initializer = Initializer
+        OnFirstEnterScrollViewerViewport(AddressOf Init)
+    End Sub
+
+    ''' <summary>
+    ''' 实例化此控件。
+    ''' </summary>
+    Public Function Init() As FrameworkElement
+        Dim Element As FrameworkElement = Initializer()
+        If Parent IsNot Nothing Then
+            If TypeOf Parent IsNot Panel Then Throw New Exception("MyVirtualizingElement 的父级必须是一个 Panel")
+            Dim ParentPanel As Panel = Parent
+            Dim CurrentIndex As Integer = ParentPanel.Children.IndexOf(Me)
+            ParentPanel.Children.RemoveAt(CurrentIndex)
+            ParentPanel.Children.Insert(CurrentIndex, Element)
+        End If
+        Return Element
+    End Function
+
+    ''' <summary>
+    ''' 获取实例化后的控件。
+    ''' 如果该控件没有实例化，则会立即实例化。
+    ''' 如果类型错误，则返回原值。
+    ''' </summary>
+    Public Shared Function TryInit(Element As FrameworkElement) As FrameworkElement
+        If GetType(MyVirtualizingElement(Of )).IsInstanceOfGenericType(Element) Then
+            Return CType(Element, Object).Init()
+        ElseIf TypeOf Element Is MyVirtualizingElement Then
+            Return CType(Element, MyVirtualizingElement).Init()
+        Else
+            Return Element
+        End If
+    End Function
+
+End Class