阻止UI线程，但继续处理传入呼叫

本文关键字：处理 入呼叫 继续 UI 线程 阻止 | 更新日期: 2023-09-27 18:26:33

我正在为3D建模应用程序开发一个插件。对于这个应用程序，还有一个第三方插件（一个渲染引擎），我想自动化它。

我所做的是创建一个Camera List<Camera> cameraViews的列表，遍历所有这些列表，并告诉渲染引擎开始渲染

foreach ( Camera camera in cameraViews )
{
    // tell the modellingApplication to apply camera
    modellingApplication.ApplyCameraToView(camera);
    // tell the render engine to render the image
    string path = "somePathWhereIWantToSaveTheImage"
    renderEngine.renderCurrentScene(path)
    // .renderCurrentScene() seems to be async, because my code, which is on the UI thread
    // continues... so:
    // make sure that the image is saved before continuing to the next image
    while ( !File.Exists(path) )
    {
        Thread.Sleep(500);
    }
}

然而，这是行不通的。renderingplugin似乎做了一些异步工作，但在做这种异步工作时，它调用的是用于检索信息的主线程。

我找到了一个解决方法：在调用渲染引擎进行渲染后，立即调用MessageBox。这将阻止代码继续运行，但异步调用仍在处理中。我知道，这是一种奇怪的行为。更奇怪的是，当渲染引擎调用UI线程获取信息并在自己的进程中继续时，我的MessageBox会自动关闭。让我的代码继续执行while循环，检查图像是否保存在磁盘上。

foreach ( Camera camera in cameraViews )
{
    // tell the modellingApplication to apply camera
    modellingApplication.ApplyCameraToView(camera);
    // tell the render engine to render the image
    string path = "somePathWhereIWantToSaveTheImage"
    renderEngine.renderCurrentScene(path)
    // .renderCurrentScene() seems to be async, because my code, which is on the UI thread
    // continues... so:
    // show the messagebox, as this will block the code but not the renderengine.. (?)
    MessageBox.Show("Currently processed: " + path);
    // hmm, messagebox gets automatically closed, that's great, but weird...
    // make sure that the image is saved before continuing to the next image
    while ( !File.Exists(path) )
    {
        Thread.Sleep(500);
    }
}

这太棒了，除了消息框部分。我不想显示消息框，我只想暂停我的代码而不阻塞整个线程（因为从渲染引擎到ui线程的调用仍然可以接受）。。

如果渲染引擎没有异步完成他的工作，那会容易得多。。

阻止UI线程，但继续处理传入呼叫

我觉得这不是最好的答案，但希望这正是你想要的。这就是阻止线程继续的方法。

    // Your UI thread should already have a Dispatcher object. If you do this elsewhere, then you will need your class to inherit DispatcherObject.
    private DispatcherFrame ThisFrame;
    public void Main()
    {
        // Pausing the Thread
        Pause();
    }
    public void Pause()
    {
        ThisFrame = new DispatcherFrame(true);
        Dispatcher.PushFrame(ThisFrame);
    }
    public void UnPause()
    {
        if (ThisFrame != null && ThisFrame.Continue)
        {
             ThisFrame.Continue = false;
             ThisFrame = null;
        }
    }

如果你想在中间阻塞的同时仍然接收并在该线程上执行操作，你可以这样做。这感觉，嗯…有点烦人，所以不要只是复制和粘贴，而不确保我没有在打字时犯一些重大错误。我还没喝咖啡。

// Used while a work item is processing. If you have something that you want to wait on this process. Or you could use event handlers or something.
private DispatcherFrame CompleteFrame;
// Controls blocking of the thread.
private DispatcherFrame TaskFrame;
// Set to true to stop the task manager.
private bool Close;
// A collection of tasks you want to queue up on this specific thread. 
private List<jTask> TaskCollection;
public void QueueTask(jTask newTask)
{
    //Task Queued.
    lock (TaskCollection) { TaskCollection.Add(newTask); }
    if (TaskFrame != null) { TaskFrame.Continue = false; }
}
// Call this method when you want to start the task manager and let it wait for a task.
private void FireTaskManager()
{
    do
    {
        if (TaskCollection != null)
        {
            if (TaskCollection.Count > 0 && TaskCollection[0] != null) 
            { 
                ProcessWorkItem(TaskCollection[0]);
                lock (TaskCollection) { TaskCollection.RemoveAt(0); }
            }
            else { WaitForTask(); }
        }
    }
    while (!Close);
}
// Call if you are waiting for something to complete.
private void WaitForTask()
{
    if (CompleteFrame != null) { CompleteFrame.Continue = false; }
    // Waiting For Task.
    TaskFrame = new DispatcherFrame(true);
    Dispatcher.PushFrame(TaskFrame);
    TaskFrame = null;
}
/// <summary>
/// Pumping block will release when all queued tasks are complete. 
/// </summary>
private void WaitForComplete()
{
    if (TaskCollection.Count > 0)
    {
        CompleteFrame = new DispatcherFrame(true);
        Dispatcher.PushFrame(CompleteFrame);
        CompleteFrame = null;
    }
}
private void ProcessWorkItem(jTask taskItem)
{
    if (taskItem != null) { object obj = taskItem.Go(); }
}
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