C# WinForm 实现CombBox 控件多选

先看效果：

 

1 建立Winform窗体工程

2.创建类 ComboBoxMutiSelect

-- 继承于CombBox

-- 设置控件双缓冲属性

-- 添加私有属性 _IsMultiSelect

-- 添加属性 IsMultiSelect

 class ComboBoxMutiSelect : ComboBox
 {
    private bool _IsMultiSelect;
    public bool IsMultiSelect { get => _IsMultiSelect; set => _IsMultiSelect = value; }
    public ComboBoxMutiSelect()
    {
      SetStyle(ControlStyles.DoubleBuffer |
      ControlStyles.OptimizedDoubleBuffer |
      ControlStyles.AllPaintingInWmPaint, true);
      UpdateStyles();
    }
}

3.创建一个对话框，添加ComboBox控件,假设该控件的对象为 comboBox1

打开对话框的设计代码：对话框名字.Desiger.cs

--修改控件声明

将
 private System.Windows.Forms.ComboBox comboBox1;
改为
 private ComboBoxMutiSelect comboBox1;

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