Question

我正在使用wpf UserControl来替换AutoCAD所选图形文件中的文件中的文本。 wpf控件用于显示状态（ProgressBar），指示在任何给定时间处理的文件数。所以我提出了以下代码，但ProgressBar根本没有显示任何进展。这是相关代码的一部分。

XAML：

<ProgressBar HorizontalAlignment="Stretch" Name="pgrSearch" Minimum="0" Maximum="{Binding Path=ProgressBarMaximum}"
                 Value="{Binding Path=ProgressBarCurrent}" Height="20" Margin="10"  />

代码隐藏：

public partial class ReplaceUserControl : UserControl, INotifyPropertyChanged {
    public ReplaceUserControl() {
        InitializeComponent();
        this.DataContext = this;
    }
    ....

    private int _progressBarMaximum;
    public int ProgressBarMaximum {
        get { return _progressBarMaximum; }
        set { _progressBarMaximum = value; RaisePropertyChanged("ProgressBarMaximum"); }
    }

    private int _progressBarCurrent;
    private int ProgressBarCurrent {
        get { return _progressBarCurrent; }
        set { _progressBarCurrent = value; RaisePropertyChanged("ProgressBarCurrent"); }
    }


    private void ReplaceTextInFiles() { //Called from Button_Click Handler
        ....

        ProgressBarMaximum = filesList.Count - 1;

        SearchReplaceWorker replaceWorker = new SearchReplaceWorker(); //The Work Horse
        replaceWorker.FileProcessed += new FileProcessedEventHandler(worker_FileProcessed); //Raised by Work Horse when each file is processed

        BackgroundWorker workerThread = new BackgroundWorker(); //The Background Worker Thread
        workerThread.DoWork += (o, e) => {
            replaceWorker.ReplaceTextInFiles(SearchText, ReplaceText, filesList, ReportFolderPath, MatchCase, MatchSubstring);
        };
        workerThread.RunWorkerAsync(); //Start the Background Thread Async
    }

    void worker_FileProcessed(object sender, EventArgs e) {
        ProgressBarCurrent = ProgressBarCurrent + 1; //Update the ProgressBar status
    }

为什么ProgressBar会在ProgressBarCurrent增加时自动更新，如上面代码所示。

修改为了在UI线程上处理ProgressBar更新代码，我将代码更改为使用BackgroundWorker.ReportProgress（），如下所示。

UserControl的CodeBehind：

private void ReplaceTextInFiles() { //Called from Button_Click()
    if (!Directory.Exists(SearchFolderPath)) {
        MessageBox.Show("Invalid Directory Selected for Search");
        return;
    }

    if (!Directory.Exists(ReportFolderPath)) {
        MessageBox.Show("Invalid Directory Selected for Report File");
        return;
    }

    List<string> filesList = null;
    try {
        if (LookInSubFolders) {
            filesList = Directory.GetFiles(@SearchFolderPath, "*.dwg", SearchOption.AllDirectories).ToList();
        }
        else {
            filesList = Directory.GetFiles(@SearchFolderPath, "*.dwg", SearchOption.TopDirectoryOnly).ToList();
        }
    }
    catch (Exception ex) {
        MessageBox.Show("Error Occurred getting the files list. Contact Admin");
    }

    pgrSearch.Visibility = Visibility.Visible;
    ProgressBarMaximum = filesList.Count - 1;

    SearchReplaceWorker replaceWorker = new SearchReplaceWorker(); 

    BackgroundWorker workerThread = new BackgroundWorker(); 
    workerThread.WorkerReportsProgress = true;
    workerThread.ProgressChanged += (o, e) => { //This event handler gets called correctly.
        ProgressBarCurrent++; 
    };
    workerThread.RunWorkerCompleted += new RunWorkerCompletedEventHandler(workerThread_RunWorkerCompleted);
    workerThread.DoWork += (o, e) => {
        replaceWorker.ReplaceTextInFiles(workerThread, SearchText, ReplaceText, filesList, ReportFolderPath, MatchCase, MatchSubstring);
    };
    workerThread.RunWorkerAsync(); 
}

BackgroundWorker：

public void ReplaceTextInFiles(BackgroundWorker workerThread, string searchText, string replaceText, List<string> filesList, string reportPath,
                                      bool MatchCase, bool MatchSubstring) {
    ...
    workerThread.ReportProgress(50);
}

ProgressBar仍然没有更新。

Answer 1

我使用您的初始代码创建了一个测试项目。过了一会儿，我发现你已将ProgressBarCurrent属性声明为私有。改为公开后，它对我有用。因此，似乎没有必要更新UI线程上的属性。在回读更新的属性值时，它看起来像是内部调用Dispatcher.Invoke。

WPF ProgressBar未更新其进度状态

1 个答案: