Question

我有一个自定义的FlowLayoutPanel：一个“AlbumFlowLayout”，它继承自FlowLayoutPanel，用于保存UserControls（“AlbumItems”）的集合。通常，这将驻留在表单（“FrmMain”）上，以便项目的层次结构为：

Form ("FrmMain")
  AlbumFlowLayout ("AlbumFlowLayout1")
    AlbumItems (1 or more)

每当创建/添加到AlbumFlowLayout时，

[有没有办法/什么是协议]为创建的AlbumItem添加“WasClicked”处理程序？

理想情况下，我想将处理程序构造代码封装在AlbumFlowLayout中，以便每当FrmMain中的代码执行新AlbumItem的AlbumFlowLayout.Controls.Add时自动发生，而不是在FrmMain中添加第二行添加添加控件之前的处理程序，例如：

Dim myItem As New AlbumItem

AddHandler myItem.WasClicked, AddressOf AlbumFlowLayout1.AlbumItem_WasClicked
AlbumFlowLayout1.Controls.Add(myItem)

谢谢！ -Pete

Answer 1

Plutonix有解决方案。以下是最终代码的用法：

Partial Public Class AlbumFlowLayout
  Inherits FlowLayoutPanel

  ' A FlowLayoutPanel for handling collections of AlbumItems

  Public SelectedItems As New List(Of String) 
  ' Holds IDs of currently selected items


  Private Sub AlbumFlowLayout_ControlAdded(sender As Object, e As ControlEventArgs) Handles Me.ControlAdded
    ' Wire up each user item as it's added so that it will pass its
    ' Wasclicked up to here

    Dim myAlbumItem As AlbumItem  = e.Control
    AddHandler myAlbumItem.WasClicked, AddressOf Me.AlbumItem_WasClicked
  End Sub

  ' Other methods...
  ' ...

  Public Sub AlbumItem_WasClicked(ByVal sender As Object, e As EventArgs)
    ' Deselects all previously selected items. Doing this via a List to
    ' Allow for expansion item where we permit multi-selection via 
    ' Control-key or the like; currently is single-select 

    Dim myItem As AlbumItem = sender

    For Each itm As String In SelectedItems
        If itm <> myItem.Name Then
            DirectCast(Me.Controls(itm), AlbumItem).IsSelected = False
        End If
    Next

    SelectedItems.Clear()
    SelectedItems.Add(myItem.Name)
  End Sub
End Class

实例化子控件时添加事件处理程序

1 个答案: