为ComboBox的item设置图片

class ComboBoxEx : ComboBox
{
    private ImageList imageList;
    public ImageList ImageList
    {
        get { return imageList; }
        set { imageList = value; }
    }

    public ComboBoxEx()
    {
        DrawMode = DrawMode.OwnerDrawFixed;
    }

    protected override void OnDrawItem(DrawItemEventArgs ea)
    {
        ea.DrawBackground();
        ea.DrawFocusRectangle();

        ComboBoxExItem item;
        Size imageSize = imageList.ImageSize;
        Rectangle bounds = ea.Bounds;

        try
        {
            item = (ComboBoxExItem)Items[ea.Index];

            if (item.ImageIndex != -1)
            {
                imageList.Draw(ea.Graphics, bounds.Left+3, bounds.Top+3,item.ImageIndex);
                ea.Graphics.DrawString(item.Text, ea.Font, new SolidBrush(ea.ForeColor), bounds.Left + imageSize.Width+3, bounds.Top+3);
            }
            else
            {
                ea.Graphics.DrawString(item.Text, ea.Font, new SolidBrush(ea.ForeColor), bounds.Left, bounds.Top);
            }
        }
        catch
        {
            if (ea.Index != -1)
            {
                ea.Graphics.DrawString(Items[ea.Index].ToString(), ea.Font, new SolidBrush(ea.ForeColor), bounds.Left, bounds.Top);
            }
            else
            {
                ea.Graphics.DrawString(Text, ea.Font, new SolidBrush(ea.ForeColor), bounds.Left, bounds.Top);
            }
        }

        base.OnDrawItem(ea);
    }
}

class ComboBoxExItem
{
    private string _text;
    public string Text
    {
        get { return _text; }
        set { _text = value; }
    }

    private int _imageIndex;
    public int ImageIndex
    {
        get { return _imageIndex; }
        set { _imageIndex = value; }
    }

    public ComboBoxExItem()
        : this(" ")
    {
    }

    public ComboBoxExItem(string text)
        : this(text, -1)
    {
    }

    public ComboBoxExItem(string text, int imageIndex)
    {
        _text = text;
        _imageIndex = imageIndex;
    }

    public override string ToString()
    {
        return _text;
    }
}

 

private void Form1_Load(object sender, EventArgs e)
{           
    ComboBoxEx cbo = new ComboBoxEx();
    cbo.ImageList = imageList1;  //imageList1 设置图片12*12
    cbo.Items.Add(new ComboBoxExItem("A1",0));
    cbo.Items.Add(new ComboBoxExItem("A2",1));
    this.Controls.Add(cbo);   //放入窗体       
}