wpf - 使用 BackgroundWorker 自动完成功能不起作用

Question

我正在使用 wpf 工具包中的 AutoCompleteBox，并且我自己实现了填充，因为有很多数据并且我想在后台线程中进行搜索。

这就是我搜索数字 12 时的结果。虽然它应该向我显示 4 个结果 - 12,120,121,122。

我究竟做错了什么 ？

我试图遵循的 msdn 指南：http: //msdn.microsoft.com/en-us/library/system.windows.controls.autocompletebox.populating (VS.95).aspx

XAML：

<Grid>
    <Controls:AutoCompleteBox x:Name="txtSearch" Populating="AutoCompleteBox_Populating" Height="30"  Background="Beige" />
</Grid>

后面的代码：

 public partial class Window1 : Window {

    private int MAX_NUM_OF_RESULTS = 3;

    public List<Person> Persons { get; set; }
    public List<string> Results { get; set; }

    public Window1() {
        InitializeComponent();

        Persons = new List<Person>();
        for (var i = 0; i < 1000000; i++) {
            Persons.Add(new Person { Name = i.ToString() });
        }

        Results = new List<string>();
    }

    private void AutoCompleteBox_Populating(object sender, PopulatingEventArgs e) {

        e.Cancel = true;

        var b = new BackgroundWorker();
        b.RunWorkerAsync(txtSearch.SearchText);
        b.DoWork += b_DoWork;
        b.RunWorkerCompleted += b_RunWorkerCompleted;
    }

    void b_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) {
        txtSearch.ItemsSource = Results;
        txtSearch.PopulateComplete();
    }


    void b_DoWork(object sender, DoWorkEventArgs e) {

        Results.Clear();
        var counter = 0;

        foreach (var person in Persons) {
            if (person.Name.StartsWith(e.Argument.ToString())) {
                Results.Add(person.Name);
                counter++;

                if (counter > MAX_NUM_OF_RESULTS) {
                    break;
                }
            }
        }
    }
}

班级人：

 public class Person {
    public string Name;
}

Answer 1

尝试将顺序更改为以下

var b = new BackgroundWorker();
b.DoWork += b_DoWork;
b.RunWorkerCompleted += b_RunWorkerCompleted;
b.RunWorkerAsync(txtSearch.SearchText);

Answer 2

您确定您的搜索逻辑实际上正在执行吗？如果是这样，在将结果分配给 ItemsSource 之前，结果中是否有预期结果？

我认为这：

    var b = new BackgroundWorker();
    b.RunWorkerAsync(txtSearch.SearchText);
    b.DoWork += b_DoWork;
    b.RunWorkerCompleted += b_RunWorkerCompleted;

应该是这样的：

    var b = new BackgroundWorker();
    b.DoWork += b_DoWork;
    b.RunWorkerCompleted += b_RunWorkerCompleted;
    b.RunWorkerAsync(txtSearch.SearchText);

否则，您可能会在设置事件处理程序之前让工作人员启动。