2021-08-13 WPF控件专题 ComboBox 控件详解

Posted 2021-09-05 微软MVP Eleven

1.ComboBox 控件介绍

• 手动添加项

• 绑定数据 代码里ItemSource IEnumerable List

  Items.Add

• DataContext =List ItemSource="{Binding}"

2.具体案例

<Grid>
    <ComboBox HorizontalAlignment="Left" Margin="96,95,0,0" VerticalAlignment="Top" Width="190" Height="30"  VerticalContentAlignment="Center" >
        <ComboBoxItem Content="请选择" IsSelected="True"></ComboBoxItem>
        <ComboBoxItem Content="软件班"></ComboBoxItem>
        <ComboBoxItem Content="英语班"></ComboBoxItem>
        <ComboBoxItem Content="数学班"></ComboBoxItem>
    </ComboBox>
    <ComboBox Name="cboClasses" HorizontalAlignment="Left" Margin="96,182,0,0" VerticalAlignment="Top" Width="190" Height="30"  VerticalContentAlignment="Center" ItemsSource="{Binding}" SelectionChanged="CboClasses_SelectionChanged">
       
    </ComboBox>
    <Button Content="Button" HorizontalAlignment="Left" Margin="162,282,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>

</Grid>

/// <summary>
/// ComboBoxWindow.xaml 的交互逻辑
/// </summary>
public partial class ComboBoxWindow : Window
{
    public ComboBoxWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        //获取数据源
        List<ClassInfo> list = GetClassInfos();

       // cboClasses.ItemsSource = list;//指定数据源
        cboClasses.SelectedValuePath = "ClassId";//项的值对应的属性名
        cboClasses.DisplayMemberPath = "ClassName";//项的显示文本对应的属性名
        cboClasses.DataContext = list;
        
        //不能直接移除，也不能添加
        //cboClasses.Items.Add(new ClassInfo()
        //{
        //    ClassId = 4,
        //    ClassName = "软件班"
        //});
        //如果仍然要添加或移除其中的项？？？  移除：先把ItemSource设置为null,然后通过list移除项，再重新指定ItemSource。
        //cboClasses.ItemsSource = null;
        //list.Add(new ClassInfo()
        //{
        //    ClassId = 4,
        //    ClassName = "软件班"
        //});
        //cboClasses.ItemsSource = list;


        //动态添加移除
        //foreach(ClassInfo cinfo in list)
        //{
        //    cboClasses.Items.Add(cinfo);
        //}

    }

    /// <summary>
    /// 获取班级列表
    /// </summary>
    /// <returns></returns>
    private List<ClassInfo> GetClassInfos()
    {
        List<ClassInfo> list = new List<ClassInfo>();
        list.AddRange(new ClassInfo[]
        {
            new ClassInfo()
            {
                ClassId=0,
                ClassName="请选择"
            },
             new ClassInfo()
            {
                ClassId=1,
                ClassName="计算机一班"
            },
             new ClassInfo()
            {
                ClassId=2,
                ClassName="计算机二班"
            },
             new ClassInfo()
            {
                ClassId=3,
                ClassName="商务英语一班"
            },
              new ClassInfo()
            {
                ClassId=3,
                ClassName="商务英语二班"
            }
        });
        return list;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        cboClasses.Items.RemoveAt(1);
    }

	//选择项改变时
    private void CboClasses_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        //MessageBox.Show((cboClasses.SelectedItem as ClassInfo).ClassName);
        //当前选定的文本、改变前的选定文本
        MessageBox.Show(cboClasses.Text);
    }
}

/// <summary>
/// 班级信息实体
/// </summary>
public class ClassInfo
{
    public int ClassId { get; set; }
    public string ClassName { get; set; }
}