借助ComboBox实现DataGridView列下拉选择效果

窗体上放置一个DataGridView控件，一个ComboBox控件，代码如下：

情况一、DataGridView的数据手工建立：

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        With DataGridView1
            '只读，不允许修改单元格内容
            .ReadOnly = True
            '禁止多选单元格
            .MultiSelect = False
            '设定行数与列数
            .RowCount = 10
            .ColumnCount = 4
            '添加DataGridView标题
            For i As Integer = 0 To .ColumnCount - 1
                .Columns(i).HeaderText = "第" & i + 1 & "列"
            Next
            '设置ComboBox样式
            ComboBox1.DropDownStyle = ComboBoxStyle.DropDownList
            '为ComboBox添加项（用数组）
            ComboBox1.Items.AddRange({"A", "B", "C"})
            '设置ComboBox的父容器为DataGridView,这样ComboBox的坐标就是相对DataGridView，而不是Form
            ComboBox1.Parent = DataGridView1
            '先不显示ComboBox
            ComboBox1.Visible = False
        End With
    End Sub

    Private Sub DataGridView1_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DataGridView1.SelectionChanged
        With DataGridView1
            '获取选定单元格的坐标:X、Y
            If .SelectedCells.Count <> 0 Then
                Dim cellX As Integer = .GetCellDisplayRectangle(.SelectedCells(0).ColumnIndex, .SelectedCells(0).RowIndex, False).X
                Dim cellY As Integer = .GetCellDisplayRectangle(.SelectedCells(0).ColumnIndex, .SelectedCells(0).RowIndex, False).Y
                '设置ComboBox的Size为选定单元格的Size
                ComboBox1.Size = .SelectedCells(0).Size
                '设置ComboBox的坐标，以便覆盖选定的单元格，达到单元格下拉效果
                ComboBox1.Left = cellX
                ComboBox1.Top = cellY
                If DataGridView1.SelectedCells(0).Value <> vbNullString Then
                    ComboBox1.Text = DataGridView1.SelectedCells(0).Value
                End If
            End If
        End With
    End Sub

    Private Sub ComboBox1_LocationChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.LocationChanged
        '选定单元格开始触发
        If DataGridView1.SelectedCells.Count <> 0 Then
            '判断哪一列显示ComboBox下拉
            If DataGridView1.SelectedCells(0).ColumnIndex = 1 Then
                ComboBox1.Visible = True
                '如果DataGridView单元格已经有数据，则让Combo的值自动显示其数据值，否则就显示空
                If DataGridView1.SelectedCells(0).Value <> vbNullString Then
                    ComboBox1.Text = DataGridView1.SelectedCells(0).Value
                Else
                    ComboBox1.SelectedIndex = -1
                End If
            Else
                ComboBox1.Visible = False
            End If
        End If
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        '将Combo的内容写入DataGridview选定的单元格
        DataGridView1.SelectedCells(0).Value = ComboBox1.Text
    End Sub

    Private Sub DataGridView1_ColumnWidthChanged(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewColumnEventArgs) Handles DataGridView1.ColumnWidthChanged
        '在允许调整DataGridView列宽的情况下，DataGridView调整列宽时，让ComboBox宽度随之改变
        If e.Column.Index = 1 Then '限定是哪一列调整列宽时才触发
            ComboBox1.Width = e.Column.Width
        End If
    End Sub
End Class

     
     
     
     

      
      
      
      

     
     
     
     

情况二、DataGridView的数据来源于DataTable：

主要演示如何手工创建DataTable，来源数据库的话比较简单，此处不演示

Imports System.Data
Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        With DataGridView1
            '只读，不允许修改单元格内容
            .ReadOnly = True
            '禁止多选单元格
            .MultiSelect = False
            '禁止删除和增加行及调整行高
            .AllowUserToAddRows = False
            .AllowUserToDeleteRows = False
            .AllowUserToResizeRows = False

            '创建DataTable()
            Dim dt As DataTable = New DataTable
            '为DataTable添加列
            dt.Columns.Add(New DataColumn("id", System.Type.GetType("System.Int32")))
            dt.Columns.Add(New DataColumn("Name", System.Type.GetType("System.String")))
            dt.Columns.Add(New DataColumn("Level", System.Type.GetType("System.String")))
            dt.Columns.Add(New DataColumn("Memo", System.Type.GetType("System.String")))
            '为DataTable添加行
            '方法一添加新行：
            Dim dr As DataRow
            dr = dt.NewRow
            dr("id") = 1
            dr("Name") = "张三"
            dt.Rows.Add(dr)
            dr = dt.NewRow
            '方法二添加新行
            dt.Rows.Add(New Object() {"2", "李四"})
            dt.Rows.Add(New Object() {"3", "王五"})

            '设置DataGridView数据源为DataTable
            .DataSource = dt

            '设置ComboBox样式
            ComboBox1.DropDownStyle = ComboBoxStyle.DropDownList
            '为ComboBox添加项（用数组）
            ComboBox1.Items.AddRange({"A", "B", "C"})
            '设置ComboBox的父容器为DataGridView,这样ComboBox的坐标就是相对DataGridView，而不是Form
            ComboBox1.Parent = DataGridView1
            '先不显示ComboBox
            ComboBox1.Visible = False
        End With
    End Sub
    Private Sub DataGridView1_ColumnWidthChanged(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewColumnEventArgs) Handles DataGridView1.ColumnWidthChanged
        '在允许调整DataGridView列宽的情况下，DataGridView调整列宽时，让ComboBox宽度随之改变
        If e.Column.Index = 2 Then '限定是哪一列调整列宽时才触发
            ComboBox1.Width = e.Column.Width
        End If
    End Sub

    Private Sub DataGridView1_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DataGridView1.SelectionChanged
        With DataGridView1
            '获取选定单元格的坐标:X、Y
            If DataGridView1.SelectedCells.Count <> 0 Then
                Dim cellX As Integer = .GetCellDisplayRectangle(.SelectedCells(0).ColumnIndex, .SelectedCells(0).RowIndex, False).X
                Dim cellY As Integer = .GetCellDisplayRectangle(.SelectedCells(0).ColumnIndex, .SelectedCells(0).RowIndex, False).Y
                '设置ComboBox的Size为选定单元格的Size
                ComboBox1.Size = .SelectedCells(0).Size
                '设置ComboBox的坐标，以便覆盖选定的单元格，达到单元格下拉效果
                ComboBox1.Left = cellX
                ComboBox1.Top = cellY
                If DataGridView1.SelectedCells(0).Value.ToString <> vbNullString Then
                    ComboBox1.Text = DataGridView1.SelectedCells(0).Value
                End If
            End If
        End With
    End Sub

    Private Sub ComboBox1_LocationChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.LocationChanged
        '选定单元格开始触发
        If DataGridView1.SelectedCells.Count <> 0 Then
            '判断哪一列显示ComboBox下拉
            If DataGridView1.SelectedCells(0).ColumnIndex = 2 Then
                ComboBox1.Visible = True
                '如果DataGridView单元格已经有数据，则让Combo的值自动显示其数据值，否则就显示空
                If DataGridView1.SelectedCells(0).Value.ToString <> vbNullString Then
                    ComboBox1.Text = DataGridView1.SelectedCells(0).Value
                Else
                    ComboBox1.SelectedIndex = -1
                End If
            Else
                ComboBox1.Visible = False
            End If
        End If
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        '将Combo的内容写入DataGridview选定的单元格
        DataGridView1.SelectedCells(0).Value = ComboBox1.Text
    End Sub
End Class