vb.net – 动态Treeview高度

2019年8月4日 253次阅读

当我加载它时,我的树视图会崩溃,因此大约100×150像素.展开后,我希望树视图显示所有展开的节点.

为了做到这一点,随着树视图变大,表单需要变大,对吧？我是VB.net的新手,我试图在树视图中找到一个“GrowOnly”属性,但我找不到一个……有没有人做过这个？

最佳答案 处理AfterExpand / AfterCollapse事件

添加事件处理程序AfterExpand和AfterCollapse以使树视图对节点的展开/折叠作出反应.我为这个例子硬编码了填充,但实质上这只是用于调整表单大小的菜单,按钮等的高度.

Private Sub Rapports_tvAllReports_AfterExpand(sender As Object, e As System.Windows.Forms.TreeViewEventArgs) Handles Rapports_tvAllReports.AfterExpand, Rapports_tvAllReports.AfterCollapse
    Dim Padding As Integer = 140 'Customize this, basically accounts for all buttons or menus included in the form which nests the treeview
    Dim TreeViewHeight As Integer = GetOpenedNodesRecursively(Rapports_tvAllReports)

    If formWindow = FormWindowState.Normal Then Me.Size = New Size(345, TreeViewHeight + Padding)
End Sub

我们所做的就是递增Y并将新Y设置为表单.为了使树视图与表单一起正确调整大小,将其锚定到顶部和底部.

递归地遍历节点

此函数将通过根节点并在打开的节点上调用递归函数.

Private Function GetOpenedNodesRecursively(ByVal aTreeView As TreeView)
    Dim Y As Integer = 0

    'Go through each node of the treeview (first level)
    For Each n As TreeNode In aTreeView.Nodes
        Y += Rapports_tvAllReports.ItemHeight

        'If the user expands a node, recursively increment the Y
        If n.IsExpanded Then Y += RecursiveYIncrement(n)
    Next

    Return Y
End Function

现在只需使用递归函数递增TreeViewHeight,该递归函数将返回在当前树视图中展开的所有节点的高度(Y).

Private Function RecursiveYIncrement(ByVal n As TreeNode)
    Dim Y As Integer = 0

    'Go through each node of the treeview (first level)
    For Each aNode As TreeNode In n.Nodes
        Y += Rapports_tvAllReports.ItemHeight

        'If the user expands a node, recursively increment the Y
        If aNode.IsExpanded Then Y += RecursiveYIncrement(aNode)
    Next

    Return Y
End Function

视觉再现

以下是我们完成后的样子：

我们从折叠的树视图开始

然后我们可以扩展一些节点,表单也会相应增长

然后我们可以重新折叠节点并扩展更多,表单再次调整！

请原谅我在屏幕截图中的法语,这是魁北克的常态……我们有义务这样做！

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