如何捕捉结束的调整大小窗口？

Question

我需要在 WPF 中捕获事件 endresize。

Answer 1

WPF 不提供仅在调整大小过程结束时触发的事件。 SizeChanged 是唯一与 Window 调整大小相关的事件 - 在调整大小的过程中它会触发多次。

总的技巧是在 SizeChanged 事件触发时不断设置计时器。然后计时器将没有机会在调整大小结束之前进行计时，然后进行一次性处理。

public MyUserControl()
{
    _resizeTimer.Tick += _resizeTimer_Tick;
}

DispatcherTimer _resizeTimer = new DispatcherTimer { Interval = new TimeSpan(0, 0, 0, 0, 1500), IsEnabled = false };

private void UserControl_SizeChanged(object sender, SizeChangedEventArgs e)
{
    _resizeTimer.IsEnabled = true;
    _resizeTimer.Stop();
    _resizeTimer.Start();
}

void _resizeTimer_Tick(object sender, EventArgs e)
{
    _resizeTimer.IsEnabled = false;    

    //Do end of resize processing
}

Answer 2

.NET 的响应式扩展提供了一些非常酷的功能来处理标准事件模式，包括能够限制事件。我在处理大小变化的事件时遇到了类似的问题，虽然解决方案仍然有点“hacky”，但我认为 Reactive Extensions 提供了一种更优雅的实现方式。这是我的实现：

IObservable<SizeChangedEventArgs> ObservableSizeChanges = Observable
    .FromEventPattern<SizeChangedEventArgs>(this, "SizeChanged")
    .Select(x => x.EventArgs)
    .Throttle(TimeSpan.FromMilliseconds(200));

IDisposable SizeChangedSubscription = ObservableSizeChanges
    .ObserveOn(SynchronizationContext.Current)
    .Subscribe(x => {
        Size_Changed(x);
    });

这将有效地限制 SizeChanged 事件，这样您的 Size_Changed 方法（您可以在其中执行自定义代码）将在没有另一个 SizeChanged 事件的情况下经过 200 毫秒（或您想等待的时间）才会执行被解雇了。

private void Size_Changed(SizeChangedEventArgs e) {
    // custom code for dealing with end of size changed here
}

Answer 3

您可以准确检测 WPF 窗口大小调整结束的时间，并且不需要计时器。当用户在窗口调整大小或移动操作结束时释放鼠标左键时，本机窗口会收到WM_EXITSIZEMOVE 消息。 WPF 窗口不接收此消息，因此我们需要连接一个WndProc 函数来接收它。我们可以使用HwndSource 和WindowInteropHelper 来获取我们的窗口句柄。然后我们将钩子添加到我们的WndProc 函数中。我们将在窗口Loaded 事件（vb.net 代码）中完成所有操作：

Dim WinSource As HwndSource    

Private Sub WindowLoaded_(sender As Object, e As RoutedEventArgs)

    WinSource = HwndSource.FromHwnd(New WindowInteropHelper(Me).Handle)
    WinSource.AddHook(New HwndSourceHook(AddressOf WndProc))
End Sub

现在，在我们的WndProc 中，我们将收听WM_EXITSIZEMOVE 消息：

Const WM_EXITSIZEMOVE As Integer = &H232

Private Function WndProc(hwnd As IntPtr, msg As Integer, wParam As IntPtr, lParam As IntPtr, ByRef handled As Boolean) As IntPtr

    If msg = WM_EXITSIZEMOVE Then

        DoWhatYouNeed()
    End If

    Return IntPtr.Zero
End Function

here 和 here 解释了这种技术和类似技术。

请注意，该函数应返回 IntPtr.Zero。另外，不要在这个函数中做任何事情，除了处理你感兴趣的特定消息。

现在，WM_EXITSIZEMOVE 也在移动操作结束时发送，我们只对调整大小感兴趣。有几种方法可以确定这是调整大小操作的结束。我通过收听WM_SIZING 消息（在调整大小期间发送了很多次）和一个标志来做到这一点。整个解决方案如下所示：

（注意：这里的代码高亮不要混淆，vb.net会出错）

Dim WinSource As HwndSource
Const WM_SIZING As Integer = &H214
Const WM_EXITSIZEMOVE As Integer = &H232

Dim WindowWasResized As Boolean = False

Private Sub WindowLoaded_(sender As Object, e As RoutedEventArgs)

    WinSource = HwndSource.FromHwnd(New WindowInteropHelper(Me).Handle)
    WinSource.AddHook(New HwndSourceHook(AddressOf WndProc))
End Sub

Private Function WndProc(hwnd As IntPtr, msg As Integer, wParam As IntPtr, lParam As IntPtr, ByRef handled As Boolean) As IntPtr

    If msg = WM_SIZING Then

        If WindowWasResized = False Then

            'indicate the the user is resizing and not moving the window
            WindowWasResized = True
        End If
    End If

    If msg = WM_EXITSIZEMOVE Then

        'check that this is the end of resize and not move operation          
        If WindowWasResized = True Then

             DoWhatYouNeed()

             'set it back to false for the next resize/move
             WindowWasResized = False
        End If            
    End If

    Return IntPtr.Zero
End Function

就是这样。

Answer 4

没有计时器需要@Bohoo 提供的非常干净的解决方案，我只是将他的代码从 vb.net 改编为 c#

     public partial class MainWindow : Window
        {
            public MainWindow()
            {
                InitializeComponent();
                this.Loaded += MainWindow_Loaded;
            }

            private void MainWindow_Loaded(object sender, RoutedEventArgs e)
            {
                // this two line have to be exactly onload
                HwndSource source = HwndSource.FromHwnd(new WindowInteropHelper(this).Handle);
                source.AddHook(new HwndSourceHook(WndProc));
            }


            const int WM_SIZING = 0x214;
            const int WM_EXITSIZEMOVE = 0x232;
            private static bool WindowWasResized = false;


            private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
            {
                if (msg == WM_SIZING)
                {

                    if (WindowWasResized == false)
                    {

                        //    'indicate the the user is resizing and not moving the window
                        WindowWasResized = true;
                    }
                }

                if (msg == WM_EXITSIZEMOVE)
                {

                    // 'check that this is the end of resize and not move operation          
                    if (WindowWasResized == true)
                    {

                        // your stuff to do 
                        Console.WriteLine("End");

                        // 'set it back to false for the next resize/move
                        WindowWasResized = false;
                    }
                }

                return IntPtr.Zero;
            }

    }

Answer 5

对于带有 Rx (System.Reactive) 的 UWP

            //Stop window updates
            rootFrame = new Frame
            {
                HorizontalAlignment = HorizontalAlignment.Left,
                VerticalAlignment = VerticalAlignment.Top,
                Width = Window.Current.Bounds.Width,
                Height = Window.Current.Bounds.Height
            };

            //updates after throttling
            var sizeChangedObservable = Observable.FromEventPattern<WindowSizeChangedEventHandler, WindowSizeChangedEventArgs>(
                      handler => Window.Current.SizeChanged += handler,
                      handler => Window.Current.SizeChanged -= handler);

            sizeChangedObservable.Throttle(TimeSpan.FromSeconds(0.35)).ObserveOnDispatcher(CoreDispatcherPriority.Normal).Subscribe(x =>
            {
                rootFrame.Width = x.EventArgs.Size.Width;
                rootFrame.Height = x.EventArgs.Size.Height;
            });