VB.NET小问题集锦(供初学者参考)

声明：

1、所有代码不注明出处的皆为本人所写

2、所有代码均在本机调试通过

3、本贴适用于初学者（本人也是）

4、欢迎各位仁兄斧正，提供想法或代码

5、本人力求每日补充内容

6、非本人同意，请勿转载本人所写的代码

7、各位说要不要上面第6条？

8、哈，声明是这样写的吗，一点都不严肃，也不规范

水如烟 2004.7.19

[控件类]

TreeView

1、给节点加个ToolTip(2004.7.19)

Private tmpTreeNode As TreeNode
Private mTreeViewToolTip As New ToolTip

Private Sub TreeView1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TreeView1.MouseMove
Dim mNode As TreeNode
mNode = Me.TreeView1.GetNodeAt(e.X, e.Y)
"当前没节点
If mNode Is Nothing Then
mTreeViewToolTip.SetToolTip(Me.TreeView1, Nothing)
Exit Sub
End If
"超过当前Node的边界
If mNode.Bounds.Right < e.X OrElse mNode.Bounds.Left > e.X Then
mTreeViewToolTip.SetToolTip(Me.TreeView1, Nothing)
Exit Sub
End If
"同一个Node
If mNode Is tmpTreeNode Then
Exit Sub
End If
mTreeViewToolTip.AutomaticDelay = 500
mTreeViewToolTip.SetToolTip(Me.TreeView1, mNode.Text)
tmpTreeNode = mNode
End Sub



DataGrid

1、自适应各列长度(2004.7.19)

"定义一个字段信息类
Private Class ColumnInfo
Public [Name] As String
Public [DataType] As String
Public MaxWidth As Integer = 0
Public Sub CompareStringLength(ByVal mString As String)
Dim mLength As Integer
mLength = System.Text.Encoding.Default.GetBytes(mString).Length()
If MaxWidth < mLength Then MaxWidth = mLength
End Sub
Public Function ColumnWidth(ByVal mDataGrid As DataGrid) As Integer
Dim mGraphics As Graphics = mDataGrid.CreateGraphics
Dim mColWidth As Single
mColWidth = mGraphics.MeasureString(New String(CType("A", Char), MaxWidth), mDataGrid.Font).Width 2
Return CType(mColWidth, Integer)
End Function
End Class


Private Sub MakeDataGridAutoExtend(ByVal mDataGrid As DataGrid)
"判断mDataGrid数据源类型
"如果绑定的是DataSet或DataViewManager或没有绑定任何数据源，则退出,
If TypeOf mDataGrid.DataSource Is System.Data.DataSet OrElse _
TypeOf mDataGrid.DataSource Is System.Data.DataViewManager OrElse _
mDataGrid.DataSource Is Nothing Then Exit Sub

"以下分别考虑两种数据源，一是DataView,一是DataTable
Dim dt As DataTable
If TypeOf mDataGrid.DataSource Is System.Data.DataView Then