winforms - 使用 ProgressBar 和 ComboBox

Question

我遇到了 Marquee 的麻烦ProgressBar .我需要执行一个方法( refreshList() )来获得 List<string> .然后我分配这个 List到 ComboBox , 所以 ComboBox用新的 Items 刷新.作为refreshList()花 3 或 4 秒，我想运行 Marquee ProgressBar .但我做不到。 ProgressBar没关系，但是ComboBox不加载新的 Items .

我的 refreshList()方法:

private void refreshList(List<string> list)
{
    albumList.DataSource = null;
    albumList.DataSource = list;
}

我有以下代码，它工作正常:

private void changeDirectoryToolStripMenuItem_Click(object sender, EventArgs e)
{
    fbd.RootFolder     = Environment.SpecialFolder.MyComputer;
    folderPath = "";
    if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
    {
        folderPath     =  fbd.SelectedPath;
        refreshList(N.getList(folderPath));

    }
}

但是我加了一个ProgressBar并写下这段代码:

private void changeDirectoryToolStripMenuItem_Click(object sender, EventArgs e)
{
    fbd.RootFolder     = Environment.SpecialFolder.MyComputer;
    folderPath = "";
    if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
    {
        folderPath     =  fbd.SelectedPath;
        bgWorker.WorkerReportsProgress = true;
        bgWorker.RunWorkerAsync();

    }
}

然后我放置了refreshList()在doWork()方法:

private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{
    refreshList(N.getList(folderPath));
}

但不幸的是，这是行不通的。谁能帮我解决这个问题？提前致谢。

Answer 1

您可以使用 MarqueeAnimationSpeed和 Value ProgressBar 控件的属性来停止和启动选取框。无需使用 WorkerReportsProgress * 因为您没有增加正常的进度条 - 您只想“旋转”选取框。

您可以执行以下操作:

    public Form1()
    {
        InitializeComponent();
        //Stop the progress bar to begin with
        progressBar1.MarqueeAnimationSpeed = 0;             
        //If you wire up the event handler in the Designer, then you don't need 
        //the following line of code (the designer adds it to InitializeComponent)
        //backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
    }

    private void changeDirectoryToolStripMenuItem_Click(object sender, EventArgs e)
    {
        fbd.RootFolder = Environment.SpecialFolder.MyComputer;
        folderPath = "";
        if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
        {
            folderPath = fbd.SelectedPath;
            //This line effectively starts the progress bar
            progressBar1.MarqueeAnimationSpeed = 10;                 
            bgWorker.RunWorkerAsync(); //Calls the DoWork event

        }
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        e.Result = N.getList(folderPath); //Technically this is the only work you need to do in the background
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        //these two lines effectively stop the progress bar
        progressBar1.Value = 0;
        progressBar1.MarqueeAnimationSpeed = 0;
        //Now update the list with the result from the work done on the background thread 
        RefreshList(e.Result as List<String>);
    }


    private void RefreshList(List<String> results)
    {
        albumList.DataSource = null; //You don't need this line but there is no real harm.
        albumList.DataSource = list;
    }

请记住通过设计器中事件部分的属性栏将 RunWorkerCompleted 事件连接到 backgroundWorker1_RunWorkerCompleted。

首先，作为您成功选择文件夹的一部分，我们通过将 MarqueeAnimationSpeed 属性设置为非零正数来启动 ProgressBar 的动画。

然后，在调用 RunWorkerAsync 之后，代码在 DoWork 方法中构建您的列表，然后将结果分配给 DoWorkEventArgs，后者传递给 RunWorkerCompleted 事件(在 DoWork 完成时触发)。

在 backgroundWorker1_RunWorkerCompleted 方法中，我们停止进度条(并将其值设置为零以有效地将其返回到原始状态)，然后我们将列表传递给 refreshList 方法以对其进行数据绑定(bind)并填充组合框。

使用 VS2012、Windows 窗体、.Net 4.0 进行测试(使用 Thread.Sleep 来模拟 N.getList 所花费的时间)

*WorkerReportsProgress 和关联的 ReportProgress 方法/事件在您想要增加进度条时使用 - 您可以告诉 GUI 您已完成 10%、20%、50% 等等。