[英]GUI updates only after the worker thread has ended
I have a Windows Form application and managed DLL in one solution. 我在一个解决方案中有一个Windows Form应用程序和托管DLL。 DLL contains some time consuming functions during which I wish to update the Form contents (callback from the DLL to the Form with progess updates).
DLL包含一些耗时的函数,在这些函数中,我希望更新表单内容(使用动态更新从DLL回调到Form)。 I have the following code:
我有以下代码:
Form code, where I initialize the DLL and give it a callback function in the Initialize method. 表单代码,我在其中初始化DLL,并在Initialize方法中为其提供回调函数。 I also start a separate Thread to periodicly check the message_queue for new messages from the DLL.
我还启动了一个单独的线程来定期检查message_queue中是否有来自DLL的新消息。 The DLL function is also called in a separate Thread (non blocking for the UI).
DLL函数也可以在单独的线程中调用(UI不阻塞)。
private LibraryDLL library_dll;
private ConcurrentQueue<string> message_queue;
public MainForm()
{
InitializeComponent();
library_dll = new LibraryDLL();
message_queue = new ConcurrentQueue<string>();
library_dll.Initialize(ProcessMessage);
new Thread(() =>
{
Thread.CurrentThread.IsBackground = true;
string message;
if (message_queue.TryDequeue(out message))
{
PrintMessage(message);
}
}).Start();
}
private void ProcessMessage(string message)
{
message_queue.Enqueue(message);
}
private void PrintMessage(string message)
{
this.Invoke((MethodInvoker)delegate
{
listBox_rows.Items.Add(message);
});
}
private void button_send_Click(object sender, EventArgs e)
{
new Thread(() =>
{
Thread.CurrentThread.IsBackground = true;
library_dll.DoWork();
}).Start();
}
In DLL code, I use the callback method to report progress: 在DLL代码中,我使用回调方法报告进度:
private CallBack callback;
public delegate void CallBack(string message);
public LibraryDLL() { }
public void Initialize(CallBack callback)
{
this.callback = callback;
}
public void DoWork()
{
callback("working...")
Thread.Sleep(500);
callback("working...")
Thread.Sleep(500);
callback("working...")
Thread.Sleep(500);
}
My problem is, that instead of string "working" appearing every 500ms, it appears 3 times after 1500ms (only after the Thread in which the DoWork method is running ends). 我的问题是,而不是字符串“ working”每500毫秒出现一次,而是在1500毫秒之后出现3次(仅在运行DoWork方法的线程结束之后)。 I also tried the Invalidate()-Update()-Refresh() sequence in the Form's PrintMessage function, but without any effect.
我还尝试了窗体的PrintMessage函数中的Invalidate()-Update()-Refresh()序列,但没有任何效果。
Thanks for the advice! 谢谢你的建议!
EDIT1: 编辑1:
I modified the code to use the BackgroundWorker, however, the problem remains (nothing for 1500ms, than all 3 strings at once). 我修改了代码以使用BackgroundWorker,但是问题仍然存在(1500ms内无任何问题,一次只剩下3个字符串)。
BackgroundWorker bck_worker;
public MainForm()
{
InitializeComponent();
library_dll = new LibraryDLL();
library_dll.Initialize(bck_worker);
bck_worker = new BackgroundWorker();
bck_worker.ProgressChanged += new ProgressChangedEventHandler(bckWorker_ProgressChanged);
bck_worker.WorkerReportsProgress = true;
bck_worker.WorkerSupportsCancellation = true;
}
private void bckWorker_DoWork(object sender, DoWorkEventArgs e)
{
library_dll.DoWork();
}
private void bckWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
PrintMessage((string)e.UserState);
}
private void button_send_Click(object sender, EventArgs e)
{
bck_worker.DoWork += new DoWorkEventHandler(bckWorker_DoWork);
bck_worker.RunWorkerAsync();
}
private void PrintMessage(string message)
{
listBox_rows.Items.Add(message);
}
And the DLL: 和DLL:
private BackgroundWorker bck_worker;
public LibraryDLL() { }
public void Initialize(BackgroundWorker bck_worker)
{
this.bck_worker = bck_worker;
}
public void DoWork()
{
bck_worker.ReportProgress(25, "working...");
Thread.Sleep(500);
bck_worker.ReportProgress(50, "working...");
Thread.Sleep(500);
bck_worker.ReportProgress(75, "working...");
Thread.Sleep(500);
}
EDIT2: 编辑2:
OK, I now tried to add the Invalidate-Update-Refresh sequence at the end of the PrintMessage function and it finaly works (with the BackgroundWorker approach)! 好的,我现在尝试在PrintMessage函数的末尾添加Invalidate-Update-Refresh序列,并且该序列最终可以工作(使用BackgroundWorker方法)!
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