我遇到了同样的问题,并且能够使用反射找到解决方法。
该问题是由 WPF 在发送窗口消息 WM_TABLET_ADDED、WM_TABLET_REMOVED 或 WM_DEVICECHANGED 时更新其内部平板电脑设备处理引起的(请参阅 .net 参考源 http://referencesource.microsoft.com/#PresentationCore/Core/CSharp/System/Windows/Input/Stylus/StylusLogic.cs,30fed96d616c6a93)。由于这些消息可能会也可能不会生成,具体取决于所使用的硬件,因此原始的 DisableWPFTabletSupport 方法可能足够,也可能不够。
我的解决方案是除了原始代码之外,还处理并隐藏 WPF 中的这三个窗口消息:
class DisableWPFTouchAndStylus
{
private static void DisableWPFTabletSupport()
{
// Get a collection of the tablet devices for this window.
var devices = Tablet.TabletDevices;
if (devices.Count > 0)
{
// Get the Type of InputManager.
var inputManagerType = typeof(InputManager);
// Call the StylusLogic method on the InputManager.Current instance.
var stylusLogic = inputManagerType.InvokeMember("StylusLogic",
BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
null, InputManager.Current, null);
if (stylusLogic != null)
{
// Get the type of the stylusLogic returned from the call to StylusLogic.
var stylusLogicType = stylusLogic.GetType();
// Loop until there are no more devices to remove.
while (devices.Count > 0)
{
// Remove the first tablet device in the devices collection.
stylusLogicType.InvokeMember("OnTabletRemoved",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic,
null, stylusLogic, new object[] { (uint)0 });
}
}
}
// END OF ORIGINAL CODE
// hook into internal class SystemResources to keep it from updating the TabletDevices on system events
object hwndWrapper = GetSystemResourcesHwnd();
if (hwndWrapper != null)
{
// invoke hwndWrapper.AddHook( .. our method ..)
var internalHwndWrapperType = hwndWrapper.GetType();
// if the delegate is already set, we have already added the hook.
if (_handleAndHideMessageDelegate == null)
{
// create the internal delegate that will hook into the window messages
// need to hold a reference to that one, because internally the delegate is stored through a WeakReference object
var internalHwndWrapperHookDelegate = internalHwndWrapperType.Assembly.GetType("MS.Win32.HwndWrapperHook");
var handleAndHideMessagesHandle = typeof(DisableWPFTouchAndStylus).GetMethod(nameof(HandleAndHideMessages), BindingFlags.Static | BindingFlags.NonPublic);
_handleAndHideMessageDelegate = Delegate.CreateDelegate(internalHwndWrapperHookDelegate, handleAndHideMessagesHandle);
// add a delegate that handles WM_TABLET_ADD
internalHwndWrapperType.InvokeMember("AddHook",
BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
null, hwndWrapper, new object[] { _handleAndHideMessageDelegate });
}
}
}
private static Delegate _handleAndHideMessageDelegate = null;
private static object GetSystemResourcesHwnd()
{
var internalSystemResourcesType = typeof(Application).Assembly.GetType("System.Windows.SystemResources");
// get HwndWrapper from internal property SystemRessources.Hwnd;
var hwndWrapper = internalSystemResourcesType.InvokeMember("Hwnd",
BindingFlags.GetProperty | BindingFlags.Static | BindingFlags.NonPublic,
null, null, null);
return hwndWrapper;
}
private static IntPtr HandleAndHideMessages(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if (msg == (int)WindowMessage.WM_TABLET_ADDED ||
msg == (int)WindowMessage.WM_TABLET_DELETED ||
msg == (int)WindowMessage.WM_DEVICECHANGE)
{
handled = true;
}
return IntPtr.Zero;
}
enum WindowMessage : int
{
WM_TABLET_DEFBASE = 0x02C0,
WM_TABLET_ADDED = WM_TABLET_DEFBASE + 8,
WM_TABLET_DELETED = WM_TABLET_DEFBASE + 9,
WM_DEVICECHANGE = 0x0219
}
}
关于此实现和限制的一些注意事项:
WPF 不会在应用程序主窗口上注册这些消息,而是通过为每个应用程序实例创建的名为“SystemResources...”的隐藏窗口注册。因此,在主窗口上处理这些消息(这很容易)在这里没有帮助。
我的解决方案还使用了相当多的反射并调用内部类和内部属性。它适用于 .net 4.6.2,尚未在早期版本上进行测试。此外,在深入研究 .net 源代码时,我还看到了更新平板电脑处理的另外两个潜在路径,但在此解决方案中未处理:TabletCollection 和 HwndStylusInputProvider 的构造函数。