我的主要目标是纯粹使用能够处理USB HID事件的P/Invoke调用实现适当的消息循环。当然,它的功能应该与以下代码相同,在Windows Forms中运行良好。由此NativeWindow后裔接收事件:实现Win32消息循环并使用P/Invoke创建Window对象
public class Win32EventHandler : NativeWindow
{
public const int WM_DEVICECHANGE = 0x0219;
public Win32EventHandler()
{
this.CreateHandle(new CreateParams());
}
protected override void OnHandleChange()
{
base.OnHandleChange();
IntPtr handle = UsbHelper.RegisterForUsbEvents(this.Handle);
}
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_DEVICECHANGE)
{
// Handle event
}
base.WndProc(ref m);
}
}
...搭载此事件循环:
Win32EventHandler handler = new Win32EventHandler();
var context = new ApplicationContext();
Application.Run(context);
// Other thread calls:
// context.ExitThread()
我发现执行事件循环是相当容易:
while (true)
{
res = Win32.GetMessage(out msg, IntPtr.Zero, 0, 0);
if (res == 0)
{
break;
}
Win32.TranslateMessage(ref msg);
Win32.DispatchMessage(ref msg);
if (msg.message == WM_DEVICECHANGE)
{
// Handle event
}
}
但我不知道如何创建底层Window对象。 NativeWindow类的实现对我来说似乎太复杂了。
这是我的解决方案的时刻:
public void CustomLoop()
{
string clsName = "Class";
string wndName = "Window";
Win32.WNDCLASSEX wndClassEx = new Win32.WNDCLASSEX();
wndClassEx.cbSize = (uint)Marshal.SizeOf(wndClassEx);
wndClassEx.lpszClassName = clsName;
wndClassEx.lpfnWndProc = WndProc;
Win32.RegisterClassEx(ref wndClassEx);
IntPtr windowHandle = Win32.CreateWindowEx(0, clsName, wndName, 0, 0, 0, 0, 0, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
IntPtr usbEventHandle = UsbHelper.RegisterForUsbEvents(windowHandle);
Win32.MSG msg;
sbyte res = 0;
while (true)
{
res = Win32.GetMessage(out msg, IntPtr.Zero, 0, 0);
if (res == 0)
{
break;
}
if (msg.message == WM.DEVICECHANGE)
{
// Handle event (does not fire)
}
else
{
Win32.TranslateMessage(ref msg);
Win32.DispatchMessage(ref msg);
}
}
Win32.DestroyWindow(windowHandle);
Win32.UnregisterClass(clsName, IntPtr.Zero);
}
[AllowReversePInvokeCalls]
private IntPtr WndProc(IntPtr hWnd, WM msg, IntPtr wParam, IntPtr lParam)
{
switch (msg)
{
case WM.DEVICECHANGE:
// Handle event (fires)
break;
default:
return Win32.DefWindowProc(hWnd, msg, wParam, lParam);
}
return IntPtr.Zero;
}
出于好奇,如果你有工作代码,你为什么要改写它不同的方式? –
我想用P/Invoke在Silverlight 5中捕获这些事件。有一个很好的理由,它完全缺乏Win32特定的东西。 – tamasf
你从pinvoke.net获得p/invoke声明? –