WPF模态窗口使用ShowDialog()会阻塞所有其他窗口

Question

我的应用程序有几个独立的“顶级”窗口，它们具有完全不同的功能/工作流程。

我目前正在使用ShowDialog()使一个WPF窗口变为模态。该模态窗口是主窗口中的子窗口。但是，一旦打开，它会阻止所有顶级窗口。我希望对话框仅阻止从它启动的父窗口。这可行吗？

我不确定它是否重要，但打开对话框的窗口是应用程序的初始窗口--因此，所有其他顶级窗口都是从它打开的。

- Phil Sandler

Answer 1

我遇到了同样的问题，并按照此帖子中描述的模态对话框行为进行实现：http://social.msdn.microsoft.com/Forums/vstudio/en-US/820bf10f-3eaf-43a8-b5ef-b83b2394342c/windowsshowmodal-to-parentowner-window-only-not-entire-application?forum=wpf

我还尝试了多线程UI的方法，但这会导致与第三方库（caliburn micro和telerik wpf controls）的问题，因为它们没有构建成用于多个UI线程。虽然可以使它们在多个UI线程中工作，但我更喜欢更简单的解决方案...

如果您按照所述方式实现对话框，则无法再使用DialogResult属性，因为它会引发“DialogResult can be set only after Window is created and shown as dialog”异常。只需实现自己的属性并使用即可。

您需要以下Windows API参考：

/// <summary>
/// Enables or disables mouse and keyboard input to the specified window or control. 
/// When input is disabled, the window does not receive input such as mouse clicks and key presses. 
/// When input is enabled, the window receives all input.
/// </summary>
/// <param name="hWnd"></param>
/// <param name="bEnable"></param>
/// <returns></returns>
[DllImport("user32.dll")]
private static extern bool EnableWindow(IntPtr hWnd, bool bEnable);

然后使用这个：

// get parent window handle
IntPtr parentHandle = (new WindowInteropHelper(window.Owner)).Handle;
// disable parent window
EnableWindow(parentHandle, false);
// when the dialog is closing we want to re-enable the parent
window.Closing += SpecialDialogWindow_Closing;
// wait for the dialog window to be closed
new ShowAndWaitHelper(window).ShowAndWait();
window.Owner.Activate();

这是一个事件处理程序，当对话框关闭时，它会重新启用父窗口：

private void SpecialDialogWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
    var win = (Window)sender;
    win.Closing -= SpecialDialogWindow_Closing;
    IntPtr winHandle = (new WindowInteropHelper(win)).Handle;
    EnableWindow(winHandle, false);

    if (win.Owner != null)
    {
        IntPtr parentHandle = (new WindowInteropHelper(win.Owner)).Handle;
        // reenable parent window
        EnableWindow(parentHandle, true);
    }
}

以下是实现模态对话框行为所需的 ShowAndWaitHelper（此方法会阻止线程的执行，但仍然会执行消息循环）。

private sealed class ShowAndWaitHelper
{
    private readonly Window _window;
    private DispatcherFrame _dispatcherFrame;
    internal ShowAndWaitHelper(Window window)
    {
        if (window == null)
        {
            throw new ArgumentNullException("window");
        }
        _window = window;
    }
    internal void ShowAndWait()
    {
        if (_dispatcherFrame != null)
        {
            throw new InvalidOperationException("Cannot call ShowAndWait while waiting for a previous call to ShowAndWait to return.");
        }
        _window.Closed += OnWindowClosed;
        _window.Show();
        _dispatcherFrame = new DispatcherFrame();
        Dispatcher.PushFrame(_dispatcherFrame);
    }
    private void OnWindowClosed(object source, EventArgs eventArgs)
    {
        if (_dispatcherFrame == null)
        {
            return;
        }
        _window.Closed -= OnWindowClosed;
        _dispatcherFrame.Continue = false;
        _dispatcherFrame = null;
    }
}

- DELUXEnized

---

你的回答非常有帮助。我已经编写了一个 async Task<DialogResult> ShowDialogAsync 扩展方法版本。 - jnm2

Answer 2

一个选项是启动那些你不想被对话框影响的窗口在不同的线程上。这可能会导致应用程序出现其他问题，但如果这些窗口确实封装了不同的工作流程，那可能不是问题。以下是我编写的一些示例代码，以验证此方法是否有效：

<Window x:Class="ModalSample.MyWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="{Binding Identifier}" Height="150" Width="150">
    <StackPanel>
        <TextBox Text="{Binding Identifier}" />
        <Button Content="Open Normal Child" Click="OpenNormal_Click" />
        <Button Content="Open Independent Child" Click="OpenIndependent_Click" />
        <Button Content="Open Modal Child" Click="OpenModal_Click" />
    </StackPanel>
</Window>

---

using System.ComponentModel;
using System.Threading;
using System.Windows;

namespace ModalSample
{
    /// <summary>
    /// Interaction logic for MyWindow.xaml
    /// </summary>
    public partial class MyWindow : INotifyPropertyChanged
    {
        public MyWindow()
        {
            InitializeComponent();
            DataContext = this;
        }

        private int child = 1;

        private string mIdentifier = "Root";
        public string Identifier
        {
            get { return mIdentifier; }
            set
            {
                if (mIdentifier == value) return;
                mIdentifier = value;
                if (PropertyChanged != null)
                    PropertyChanged(this, new PropertyChangedEventArgs("Identifier"));
            }
        }

        private void OpenNormal_Click(object sender, RoutedEventArgs e)
        {
            var window = new MyWindow {Identifier = Identifier + "-N" + child++};
            window.Show();
        }

        private void OpenIndependent_Click(object sender, RoutedEventArgs e)
        {
            var thread = new Thread(() =>
                {
                    var window = new MyWindow {Identifier = Identifier + "-I" + child++};
                    window.Show();

                    window.Closed += (sender2, e2) => window.Dispatcher.InvokeShutdown();

                    System.Windows.Threading.Dispatcher.Run();
                });

            thread.SetApartmentState(ApartmentState.STA);
            thread.Start();
        }

        private void OpenModal_Click(object sender, RoutedEventArgs e)
        {
            var window = new MyWindow { Identifier = Identifier + "-M" + child++ };
            window.ShowDialog();
        }

        public event PropertyChangedEventHandler PropertyChanged;
    }
}

我获取了这篇博客文章，用于在不同线程上运行WPF窗口。

- Joseph Sturtevant