DataGridViewでセルに強制的に画像を表示する方法

DataGridViewでセルに強制的に画像を表示する方法
VB.NET

Public Class DataGridViewErrorIconColumn
    Inherits DataGridViewImageColumn

    Public Sub New()
        Me.CellTemplate = New DataGridViewErrorIconCell()
        Me.ValueType = Me.CellTemplate.ValueType
    End Sub
End Class

Public Class DataGridViewErrorIconCell
    Inherits DataGridViewImageCell

    Public Sub New()
        Me.ValueType = GetType(Integer)
    End Sub

    Protected Overrides Function GetFormattedValue( _
        ByVal value As Object, ByVal rowIndex As Integer, _
        ByRef cellStyle As DataGridViewCellStyle, _
        ByVal valueTypeConverter As System.ComponentModel.TypeConverter, _
        ByVal formattedValueTypeConverter As System.ComponentModel.TypeConverter, _
        ByVal context As DataGridViewDataErrorContexts) As Object
        Select Case CInt(value)
            Case 1
                Return SystemIcons.Information
            Case 2
                Return SystemIcons.Warning
            Case 3
                Return SystemIcons.Error
            Case Else
                Return Nothing
        End Select
    End Function

    Public Overrides ReadOnly Property DefaultNewRowValue() As Object
        Get
            Return 0
        End Get
    End Property
End Class

Dim iconColumn As New DataGridViewErrorIconColumn()
iconColumn.DataPropertyName = "col1"
dgv1.Columns.Add(iconColumn)

C#

using System;
using System.ComponentModel;
using System.Windows.Forms;

public class DataGridViewErrorIconColumn : DataGridViewImageColumn
{
    public DataGridViewErrorIconColumn()
    {
        this.CellTemplate = new DataGridViewErrorIconCell();
        this.ValueType = this.CellTemplate.ValueType;
    }
}

public class DataGridViewErrorIconCell : DataGridViewImageCell
{
    public DataGridViewErrorIconCell()
    {
        this.ValueType = typeof(int);
    }

    protected override object GetFormattedValue(
        object value, int rowIndex,
        ref DataGridViewCellStyle cellStyle,
        TypeConverter valueTypeConverter,
        TypeConverter formattedValueTypeConverter,
        DataGridViewDataErrorContexts context)
    {
        switch ((int)value)
        {
            case 1:
                return SystemIcons.Information;
            case 2:
                return SystemIcons.Warning;
            case 3:
                return SystemIcons.Error;
            default:
                return null;
        }
    }

    public override object DefaultNewRowValue
    {
        get
        {
            return 0;
        }
    }
}

DataGridViewErrorIconColumn iconColumn =
    new DataGridViewErrorIconColumn();
iconColumn.DataPropertyName = "col1";
dgv1.Columns.Add(iconColumn);