Winform WaitScreen实现

Question

我有以下WaitScreen类在执行后台进程时显示“请稍候...”消息：

public class WaitScreen
    {
        // Fields
        private object lockObject = new object();
        private string message = "Please Wait...";
        private Form waitScreen;

        // Methods
        public void Close()
        {
            lock (this.lockObject)
            {
                if (this.IsShowing)
                {
                    try
                    {
                        this.waitScreen.Invoke(new MethodInvoker(this.CloseWindow));
                    }
                    catch (NullReferenceException)
                    {
                    }
                    this.waitScreen = null;
                }
            }
        }

        private void CloseWindow()
        {
            this.waitScreen.Dispose();
        }

        public void Show(string message)
        {
            if (this.IsShowing)
            {
                this.Close();
            }
            if (!string.IsNullOrEmpty(message))
            {
                this.message = message;
            }
            using (ManualResetEvent event2 = new ManualResetEvent(false))
            {
                Thread thread = new Thread(new ParameterizedThreadStart(this.ThreadStart));
                thread.SetApartmentState(ApartmentState.STA);
                thread.Start(event2);
                event2.WaitOne();
            }
        }

        private void ThreadStart(object parameter)
        {
            Application.SetUnhandledExceptionMode(UnhandledExceptionMode.ThrowException);
            ManualResetEvent event2 = (ManualResetEvent)parameter;
            Application.EnableVisualStyles();
            this.waitScreen = new Form();
            this.waitScreen.Tag = event2;
            this.waitScreen.ShowIcon = false;
            this.waitScreen.ShowInTaskbar = false;
            this.waitScreen.AutoSize = true;
            this.waitScreen.AutoSizeMode = AutoSizeMode.GrowAndShrink;
            this.waitScreen.BackColor = SystemColors.Window;
            this.waitScreen.ControlBox = false;
            this.waitScreen.FormBorderStyle = FormBorderStyle.FixedToolWindow;
            this.waitScreen.StartPosition = FormStartPosition.CenterScreen;
            this.waitScreen.Cursor = Cursors.WaitCursor;
            this.waitScreen.Text = "";
            this.waitScreen.FormClosing += new FormClosingEventHandler(this.WaitScreenClosing);
            this.waitScreen.Shown += new EventHandler(this.WaitScreenShown);
            Label label = new Label();
            label.Text = this.message;
            label.AutoSize = true;
            label.Padding = new Padding(20, 40, 20, 30);
            this.waitScreen.Controls.Add(label);
            Application.Run(this.waitScreen);
            Application.ExitThread();
        }

        private void WaitScreenClosing(object sender, FormClosingEventArgs e)
        {
            if (e.CloseReason == CloseReason.UserClosing)
            {
                e.Cancel = true;
            }
        }

        private void WaitScreenShown(object sender, EventArgs e)
        {
            Form form = (Form)sender;
            form.Shown -= new EventHandler(this.WaitScreenShown);
            ManualResetEvent tag = (ManualResetEvent)form.Tag;
            form.Tag = null;
            tag.Set();
        }

        // Properties
        public bool IsShowing
        {
            get
            {
                return (this.waitScreen != null);
            }
        }
    }

我使用它的方式是：

waitScreen = new WaitScreen();
waitScreen.Show("Please wait...");

我有一个MainForm，在mainform中我有一个按钮，当点击时我会显示一个Dialog，在加载时会从Backgroundworker中的数据库中获取一些数据。在运行backgroundworker之前，我会显示 WaitScreen 。

它工作得很好但是当显示 WaitScreen 时如果我点击后面的对话框，那么 WaitScreen 就消失了。所以我想阻止，所以我不能点击后面的对话框，直到工人完成，然后我关闭 WaitScreen 。

有关如何做到这一点的任何线索？

非常感谢。

Answer 1

我认为你过于复杂了。你想要的是一个模态对话窗口，用户无法关闭，当给定任务完成时，该窗口将关闭。

您可以创建一个派生自Form的标准类，并实现可以传递Task或回调的构造函数或属性。

以下是您的WaitScreen表单中的代码：

public partial class WaitScreen : Form
{
    public Action Worker { get; set; }

    public WaitScreen(Action worker)
    {
        InitializeComponent();

        if (worker == null)
            throw new ArgumentNullException();

        Worker = worker;
    }

    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);

        Task.Factory.StartNew(Worker).ContinueWith(t => { this.Close(); }, TaskScheduler.FromCurrentSynchronizationContext());
    }
}

以下是您的代码在此WaitScreen表单的使用者中的样子：

private void someButton_Click(object sender, EventArgs e)
{
    using (var waitScreen = new WaitScreen(SomeWorker))
        waitScreen.ShowDialog(this);
}

private void SomeWorker()
{
    // Load stuff from the database and store it in local variables.
    // Remember, this is running on a background thread and not the UI thread, don't touch controls.
}

您可能希望在WaitScreen中使用FormBorderStyle.None，以便用户无法关闭它。然后任务完成，WaitScreen将自行关闭，调用者将在ShowDialog()调用后继续执行代码。 ShowDialog()阻止调用线程。