Question

我想通过操纵不透明度值来设置GUI上的Control透明。因此，我在WPF-Form的构造函数上初始化BackgroundWorker，如：

volumeWorker = new BackgroundWorker();
volumeWorker.DoWork += new DoWorkEventHandler(VolumeBarDoWork);
volumeWorker.ProgressChanged += new ProgressChangedEventHandler(VolumeBarChanged);
volumeWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(VolumeBarCompleted);
volumeWorker.WorkerReportsProgress = true;

之后，我的GUI等待一个由另一个类

触发的事件

soundController = new SoundController();
soundController.VolumeChanged +=new SoundController.VolumeChangedEventHandler(VolumeChanged);

在事件处理程序上，我最终将启动volumeWorker（BGW）来操作GUI：

private void VolumeChanged(float pVolume)
{
    Logger.InfoWrite("Event raised ## New volume : {0}", pVolume);
    volumeWorker.RunWorkerAsync();
}

但是在BackgroundWorkers ChangeEvent上，每次都有一个InvalidOperationException。有人知道吗？

private void VolumeBarDoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;
    Logger.InfoWrite("Worker");
    for(int _opacity = 99 ; _opacity >= 0 ; _opacity--)
    {
        Logger.InfoWrite("Start on {0}", _opacity);
        worker.ReportProgress(_opacity);
        System.Threading.Thread.Sleep(20)
    }
    e.Result = e.Argument;
}

private void VolumeBarChanged(object sender, ProgressChangedEventArgs e)
{
    this.volumeBar.Opacity -= 0.01f;
    Logger.InfoWrite("Changed opacity to : {0} on {1}", this.volumeBar.Opacity, e.ProgressPercentage);
}

private void VolumeBarCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    Logger.InfoWrite("Completed");
    this.volumeBar.Opacity = 0.0f;
}

Answer 1

您无法直接在UI线程之外更改UI，因为UI控件是在UI线程上创建的。请改用Dispatcher.Invoke或BeginInvoke方法。

使用BackgroundWorker调用WPF-GUI-Changes时出现异常

1 个答案: