Error Marshaling Structure

[RapidFireBill]

I am getting this error:

"System.ArgumentException occurred in mscorlib.dll. Field passed in is not a
marshaled member of the type A10CSS.A10+MSG".

in the following code snippet where I am servicing a hooks callback. Any
suggestions? Thanks!

...
namespace A10CSS
{
public class A10 : System.Windows.Forms.Form
{
...
private LocalWindowsHook m_lwh;
...
public A10() : base()
{
m_lwh = new LocalWindowsHook(HookType.WH_GETMESSAGE);
m_lwh.HookInvoked += new
LocalWindowsHook.HookEventHandler(m_lwh_HookInvoked);
}
...
protected override void WndProc(ref Message m)
{
Debug.WriteLine(m.Msg);
const int WM_CREATE = 0x0001;
const int WM_DESTROY = 0x0002;
if (m.Msg == WM_CREATE)
{
m_lwh.Install();
Debug.WriteLine ("Hook Installed");
}
if (m.Msg == WM_DESTROY)
{
m_lwh.Uninstall();
Debug.WriteLine ("Hook Uninstalled");
}
base.WndProc (ref m);
}

private void m_lwh_HookInvoked(object sender, HookEventArgs e)
{
const int WM_NULL = 0;
const int PM_REMOVE = 0x0001;
const int WM_KEYFIRST = 0x0100;
const int WM_KEYLAST = 0x0109;
if (e.HookCode >= 0 && new IntPtr(PM_REMOVE) == e.wParam)
{
// following line is where I get the "System.ArgumentException
// occurred in mscorlib.dll Field passed in is not a marshaled member of the
type A10CSS.A10+MSG".
uint msg = (uint)Marshal.ReadInt32(e.lParam,
Marshal.OffsetOf(typeof(MSG), "Msg").ToInt32());
if(msg >= WM_KEYFIRST && msg <= WM_KEYLAST)
{
if(IsDialogMessage(this.Handle, e.lParam) != 0)
{
Marshal.WriteInt32(e.lParam, Marshal.OffsetOf(typeof(MSG),
"Msg").ToInt32(), WM_NULL);
Marshal.WriteInt32(e.lParam, Marshal.OffsetOf(typeof(MSG),
"wParam").ToInt32(), 0);
Marshal.WriteInt32(e.lParam, Marshal.OffsetOf(typeof(MSG),
"lParam").ToInt32(), 0);
}
}
}
}

[ StructLayout(LayoutKind.Sequential) ]
struct MSG
{
IntPtr hwnd;
uint Msg;
IntPtr wParam;
IntPtr lParam;
int time;
//POINT pt
int x;
int y;
}

[DllImport("user32.dll")]
private static extern int IsDialogMessage(IntPtr hDlg, IntPtr lpMsg);
}
}

--
<_/\_> RapidFireBill
--
<_/\_>

[saurabh]

you can directly do something like this :
Message msg =
(Message)System.Runtime.InteropServices.Marshal.PtrToStructure(lParam,
typeof(Message));

Since it marshals to the .NET message structure, you don't even need to
declare your own message structure.

Hope this helps,

--Saurabh

"RapidFireBill" <RapidF...@discussions.microsoft.com> wrote in message
news:6F02BB5A-6EF2-4CA7...@microsoft.com...

[saurabh]

This is how your hookproc should look like, please note that I am pasting
just the proc here. I have defined the constants and imports in same class.

public int YourHookProc(int nCode, IntPtr wParam, IntPtr lParam)
{

Message msg =
(Message)System.Runtime.InteropServices.Marshal.PtrToStructure(lParam,
typeof(Message));

if (nCode >= 0 && PM_REMOVE == wParam.ToInt32())
{
if ((msg.Msg >= WM_KEYFIRST) &&(msg.Msg <= WM_KEYLAST))
{
long i = IsDialogMessage(this.Handle, ref msg);
if (i != 0)
{
msg.Msg = 0;
msg.LParam = IntPtr.Zero;
msg.WParam = IntPtr.Zero;
System.Runtime.InteropServices.Marshal.StructureToPtr(msg, lParam,
true);
}
}
}
return CallNextHookEx(hTabHook, nCode, wParam, lParam);

}

HTH,

--Saurabh

"RapidFireBill" <RapidF...@discussions.microsoft.com> wrote in message
news:6F02BB5A-6EF2-4CA7...@microsoft.com...

[RapidFireBill]

Thanks now my IsDialogMessage call is working.

My tab keys are working, but SHIFT-TAB does not reverse the tabbing
direction. Also my arrow keys work, but on RadioButtons, they do not traverse
the RadioButtons in a circular pattern.

I would like them to work like when I launched my dialog 'Modal' with
A10.ShowDialog in a separate thread (my parent app stayed open in TaskManager
after I closed the parent app). But the IsDialogMessage method tabbing &
arrowing behaviour is different than Modal in a thread.

Do you know why this behaviour is different?

[JonS.]

Bill,

I'm having the same issue, and hopefully you're still watching this thread.
Anyways, I was able to get it to work by making all the struct members public
from the original example, and everything seemed okay, however I have another
problem and could really use your feedback.

When someone presses the 'TAB' key, it's going through the tab stops in
reverse order. I would greatly appreciate some help on this issue.

Thanks,

Jon

[Saleem]

Hi,

The tabs are working for me. But they are not following in the order set, They are doing randon tabs, though I have set the tab order correctly.
Any puts will be great.

Saleem

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