什么会导致WM_NCHITTEST lParam溢出32位整数?

本文关键字：溢出 lParam 32位整数 NCHITTEST WM 什么 | 更新日期: 2023-09-27 18:18:48

消息WM_NCHITTEST的lParam在什么情况下不适合32位整数?

我们的一个客户在他的64位机器上看到崩溃，原因是我们的WPF应用程序中出现了一个未处理的异常，我很难找到原因。从WPF代码引发异常，如堆栈跟踪所示:

System.OverflowException: Arithmetic operation resulted in an overflow.
   at Microsoft.Windows.Shell.WindowChromeWorker._HandleNCHitTest(WM uMsg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled)
   at Microsoft.Windows.Shell.WindowChromeWorker._WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled)
   at System.Windows.Interop.HwndSource.PublicHooksFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)&#xD;&#xA;   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

违规方法_HandleNCHitTest的来源在这里。

我能看到被抛出的溢出异常的唯一方法是在将lParam转换为Point的代码中，它在这里调用IntPtr.ToInt32()。如果lParam不适合Int32，则引发此异常。然而，我想不出这种情况何时会发生。是什么让这一切发生呢?

什么会导致WM_NCHITTEST lParam溢出32位整数?

简短的回答:使用。net 4.5以来集成的WindowChrome。

很长的回答，如果你不能切换到。net 4.5，这似乎对我有用，看看我对最初问题的评论。您永远无法确定，因为问题有时只在某些机器上显示，而不是所有的x64机器:

我修改了WPF Shell集成库v2的源代码。更改后的行在末尾用<----标记。

WindowChromeWorker.cs:

    private IntPtr _HandleSize(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled)
    {
        const int SIZE_MAXIMIZED = 2;
        // Force when maximized.
        // We can tell what's happening right now, but the Window doesn't yet know it's
        // maximized.  Not forcing this update will eventually cause the
        // default caption to be drawn.
        WindowState? state = null;
        if (wParam.ToInt64() == SIZE_MAXIMIZED)  <-----
        {
            state = WindowState.Maximized;
        }
        _UpdateSystemMenu(state);
        // Still let the default WndProc handle this.
        handled = false;
        return IntPtr.Zero;
    }

Utilities.cs:

    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static int GET_X_LPARAM(IntPtr lParam)
    {
        return LOWORD(lParam.ToInt64());    <----
    }
    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static int GET_Y_LPARAM(IntPtr lParam)
    {
        return HIWORD(lParam.ToInt64());    <----
    }
    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static int HIWORD(long i)    <----
    {
        return (short)((i >> 16) & 0xFFFF);    <----
    }
    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static int LOWORD(long i)    <----
    {
        return (short)(i & 0xFFFF);
    }

TaskbarItemInfo.cs:

    private IntPtr _WndProc(IntPtr hwnd, int uMsg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        WM message = (WM)uMsg;
        if (message == WM_TASKBARBUTTONCREATED)
        {
            _OnIsAttachedChanged(true);
            _isAttached = true;
            handled = false;
        }
        else
        {
            switch (message)
            {
                case WM.COMMAND:
                    if (Utility.HIWORD(wParam.ToInt64()) == THUMBBUTTON.THBN_CLICKED)  <-----
                    {
                        int index = Utility.LOWORD(wParam.ToInt64());   <----
                        ThumbButtonInfos[index].InvokeClick();
                        handled = true;
                    }
                    break;
                case WM.SIZE:
                    _UpdateThumbnailClipping(_isAttached);
                    handled = false;
                    break;
            }
        }
        return IntPtr.Zero;
    }

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