如何创建带有不可选择项的组合框控件?例如,将组名或类别名用于视觉上将下拉列表中的项目分成一些组或类别。
您可以添加一个特殊的类,而不是将字符串添加到组合框中,并使用所选项目来确定该项目是否已被选中。
public partial class Form1 : Form
{
private class ComboBoxItem
{
public int Value { get; set; }
public string Text { get; set; }
public bool Selectable { get; set; }
}
public Form1() {
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e) {
this.comboBox1.ValueMember = "Value";
this.comboBox1.DisplayMember = "Text";
this.comboBox1.Items.AddRange(new[] {
new ComboBoxItem() { Selectable = false, Text="Unselectable", Value=0},
new ComboBoxItem() { Selectable = true, Text="Selectable1", Value=1},
new ComboBoxItem() { Selectable = true, Text="Selectable2", Value=2},
new ComboBoxItem() { Selectable = false, Text="Unselectable", Value=3},
new ComboBoxItem() { Selectable = true, Text="Selectable3", Value=4},
new ComboBoxItem() { Selectable = true, Text="Selectable4", Value=5},
});
this.comboBox1.SelectedIndexChanged += (cbSender, cbe) => {
var cb = cbSender as ComboBox;
if (cb.SelectedItem != null && cb.SelectedItem is ComboBoxItem && ((ComboBoxItem) cb.SelectedItem).Selectable == false) {
// deselect item
cb.SelectedIndex = -1;
}
};
}
}