[NET.VB]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
        dt = CType(mDataGrid.DataSource, DataView).Table
    Else
        dt = CType(mDataGrid.DataSource, DataTable)
    End If

    ''''取各字段信息
    Dim mColumnInfo(dt.Columns.Count - 1) As ColumnInfo

    Dim i As Integer = 0

    Dim mColumn As DataColumn
    For Each mColumn In dt.Columns
        Dim mInfo As New ColumnInfo
        With mInfo
            .Name = mColumn.ColumnName
            .DataType = mColumn.DataType.ToString
            .CompareStringLength( mColumn.ColumnName)
        End With
        mColumnInfo(i) = mInfo
        i += 1
    Next

    ''''取各字段的最大长度
    Dim mRow As DataRow
    For Each mRow In dt.Rows
        For i = 0 To dt.Columns.Count - 1
            If Not IsDBNull(mRow(i)) Then
                mColumnInfo(i).CompareStringLength(CType(mRow(i), String))
            End If
        Next
    Next

    ''''建DataGridTableStyle
    Dim ts As New DataGridTableStyle
    ts.MappingName = dt.TableName

    For i = 0 To dt.Columns.Count - 1
        If  mColumnInfo(i).DataType.Equals("System.Boolean") Then
            ''''这是Boolean字段
            Dim blnCol As New DataGridBoolColumn
            With blnCol
                .MappingName = mColumnInfo(i).Name
                .HeaderText = mColumnInfo(i).Name
                .Width = mColumnInfo(i).ColumnWidth(mDataGrid)
                .NullText = ""
            End With
            ts.GridColumnStyles.Add(blnCol)
        Else
            ''''非Boolean字段
            Dim TxtCol As New DataGridTextBoxColumn
            With TxtCol
                .MappingName = mColumnInfo(i).Name
                .HeaderText = mColumnInfo(i).Name
                .Width = mColumnInfo(i).ColumnWidth(mDataGrid)
                .NullText = ""
                .ReadOnly = False ''''这里可以设置为只读
                .Format = "" ''''这里可以设置显示格式，要显示日时分秒的就在这设
            End With
            ts.GridColumnStyles.Add(TxtCol)
        End If
    Next

    mDataGrid.TableStyles.Clear()
    mDataGrid.TableStyles.Add(ts)
    ''''至于其它的功能，比如绑定事件之类的，后面再补充
End Sub
　

''''调用
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    MakeDataGridAutoExtend(M

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