回答链接：(Can I put a horizontal line in a combo box or list control?)

我已经在C#(VS 2010)Windows窗体中创建了一个代码,但是需要改进.项目前面的符号“-”在项目之后显示一行.

我在组合项目集合中的输入如下：

-All Names
Henry (Father)
-Nancy (Mother)
Sapphire
Vincent

我的组合显示如下：

All Names
------------------
Henry (Father)
Nancy (Mother)
------------------
Sapphire
Vincent

虽然我的代码是：

    public Form1()
    {
        InitializeComponent();
        comboBox1.DrawMode = DrawMode.OwnerDrawFixed;
        comboBox1.DrawItem += new DrawItemEventHandler(cmb_Type_DrawItem);
    }

    void cmb_Type_DrawItem(object sender, DrawItemEventArgs e)
    {
        e.DrawBackground();
        string a = comboBox1.Items[e.Index].ToString();
        if (comboBox1.Items[e.Index].ToString().Substring(0, 1) == "-")
        {
            e.Graphics.DrawLine(Pens.Black, new Point(e.Bounds.Left, e.Bounds.Bottom - 1),
            new Point(e.Bounds.Right, e.Bounds.Bottom - 1));
            a = a.Substring(1, a.Length - 1);
        }            
        TextRenderer.DrawText(e.Graphics, a,
        comboBox1.Font, e.Bounds, comboBox1.ForeColor, TextFormatFlags.Left);
        e.DrawFocusRectangle();
    }

我需要的改进是在“ cmb_Type_DrawItem”中,我希望对“ comboBox1”进行参数设置,以便在我调用它时可以将其应用于任何调用它的comboBox(而不仅仅是comboBox1).

解决方法:

您可以按照Blau的建议进行操作,也可以创建将事件处理程序附加到组合框的函数.

void AttachHandler(ComboBox combo) {
    combo.DrawMode = DrawMode.OwnerDrawFixed;
    combo.DrawItem += new DrawItemEventHandler(cmb_Type_DrawItem);
}

然后,在表单构造函数中,您只需使用：

public Form1() {
    AttachHandler(comboBox1);
    AttachHandler(comboBox2);
}