Mar*_*tin 27
WPF不提供仅在调整大小过程结束时触发的事件.SizeChanged是与Window大小调整相关联的唯一事件 - 它将在调整大小过程中多次触发.
完全破解是在SizeChanged事件触发时不断设置计时器滴答.然后计时器将无法勾选,直到调整结束并在那时进行一次处理.
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
}
Jes*_*ter 13
.NET的Reactive Extensions为处理标准事件模式提供了一些非常酷的功能,包括能够限制事件.我在处理大小更改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,这样你的Size_Changed方法(你可以执行自定义代码)将不会被执行,直到200毫秒(或者你想等待的时间长)已经过去而没有SizeChanged被触发的另一个事件.
private void Size_Changed(SizeChangedEventArgs e) {
// custom code for dealing with end of size changed here
}
不需要计时器，@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;
}
}
您可以准确地检测WPF窗口调整大小的结束时间，并且不需要计时器。WM_EXITSIZEMOVE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，本机窗口会收到此消息。WPF窗口没有收到此消息，因此我们需要连接一个WndProc将接收该消息的函数。我们可以使用HwndSourcewith WindowInteropHelper来获取窗口句柄。然后我们将钩子添加到我们的WndProc函数中。我们将在window Loaded事件（vb.net代码）中执行所有操作：
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，在我们的中WndProc，我们将收听以下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
请注意，该函数应返回IntPtr.Zero。另外，除了处理您感兴趣的特定消息外，请勿在此功能中进行任何操作。
现在， WM_EXITSIZEMOVE在移动操作结束时也会发送，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。我通过听WM_SIZING消息（在调整大小期间发送了多次）并结合一个标志来做到这一点。整个解决方案如下所示：
（注意：不要与此处突出显示的代码混淆，对vb.net造成错误）
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
而已。