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From: Kerem Gümrükcü on 30 Jan 2009 14:02
Hi,

can someone please tell me why this class i created runs into
a access violation after some while running it. It throws the exception
after a unsepcified amount if time. Its pretty a pointer problem, but
where do i have to check what?

[StructLayout(LayoutKind.Sequential,CharSet=CharSet.Unicode)]
public struct CWPSTRUCT
{
public IntPtr lParam;
public IntPtr wParam;
public int message;
public IntPtr hwnd;
}

public enum HookType : int
{
WH_JOURNALRECORD = 0,
WH_JOURNALPLAYBACK = 1,
WH_KEYBOARD = 2,
WH_GETMESSAGE = 3,
WH_CALLWNDPROC = 4,
WH_CBT = 5,
WH_SYSMSGFILTER = 6,
WH_MOUSE = 7,
WH_HARDWARE = 8,
WH_DEBUG = 9,
WH_SHELL = 10,
WH_FOREGROUNDIDLE = 11,
WH_CALLWNDPROCRET = 12,
WH_KEYBOARD_LL = 13,
WH_MOUSE_LL = 14
}

public delegate int HookProc(int code, IntPtr wParam, IntPtr
lParam);

public delegate int HookProcCWPS(int code, IntPtr wParam, ref
CWPSTRUCT cwps);

[DllImport("kernel32.dll")]
public static extern uint GetCurrentThreadId();

[DllImport("user32.dll", SetLastError = true,CharSet =
CharSet.Unicode)]
public static extern IntPtr SetWindowsHookEx(HookType hook,
HookProcCWPS callback,
IntPtr hMod, uint dwThreadId);

[DllImport("user32.dll", SetLastError = true, CharSet =
CharSet.Unicode)]
public static extern IntPtr SetWindowsHookEx(HookType hook, HookProc
callback,
IntPtr hMod, uint dwThreadId);

[DllImport("user32.dll", CharSet = CharSet.Unicode)]
public static extern int CallNextHookEx(IntPtr hhk, int nCode,
IntPtr wParam,
IntPtr lParam);

[DllImport("user32.dll", CharSet = CharSet.Unicode)]
public static extern int CallNextHookEx(IntPtr hhk, int nCode,
IntPtr wParam,
ref CWPSTRUCT cwps);

[DllImport("user32.dll", SetLastError = true, CharSet =
CharSet.Unicode)]
public static extern bool UnhookWindowsHookEx(IntPtr hhk);

public class DRWindowHelperClass
{
private IntPtr windowHandle;
private IntPtr hhk;
private Exception exception;

public delegate void WindowMessageArrivedDelegate(ref Message
WindowMessage);
public event WindowMessageArrivedDelegate WindowMessageArrived;

public DRWindowHelperClass(IntPtr WindowHandle)
{
this.windowHandle = WindowHandle;
}

public Exception LastException
{
set
{
this.exception = value;
}

get
{
return this.exception;
}
}

public bool SetWindowsHook()
{
try
{
this.hhk =
DRWin32APIClass.SetWindowsHookEx(DRWin32APIClass.HookType.WH_CALLWNDPROC,
this.WndHookProcWPCS, IntPtr.Zero, DRWin32APIClass.GetCurrentThreadId());

if (this.hhk == IntPtr.Zero)
{
throw new Win32Exception();
}

this.exception = new Win32Exception(0);
return true;
}
catch (Exception err)
{
this.exception = err;
return false;
}
}

private int WndHookProcWPCS(int code, IntPtr wParam, ref
DRWin32APIClass.CWPSTRUCT cwps)
{
if (code < 0)
{
return DRWin32APIClass.CallNextHookEx(IntPtr.Zero, code,
wParam, ref cwps);
}
else
{
if (this.WindowMessageArrived != null)
{

Message m = new Message();
m.HWnd = cwps.hwnd;
m.LParam = cwps.lParam;
m.WParam = cwps.lParam;
m.Msg = cwps.message;
m.Result = new IntPtr(0);
this.WindowMessageArrived(ref m);
}

return DRWin32APIClass.CallNextHookEx(IntPtr.Zero, code,
wParam, ref cwps);
}
}

public bool RemoveWindowsHook()
{
try
{
if (DRWin32APIClass.UnhookWindowsHookEx(this.hhk) == true)
{
this.exception = new Win32Exception(0);
return true;
}
else
{
throw new Win32Exception();
}
}
catch (Exception err)
{
this.exception = err;
return false;
}
}

~DRWindowHelperClass()
{
if (this.hhk != IntPtr.Zero)
{
DRWin32APIClass.UnhookWindowsHookEx(this.hhk);
}
}

public IntPtr WindowHandle
{
get
{
return this.windowHandle;
}
}
}

Regards

Kerem

--
--
-----------------------
Beste Gr�sse / Best regards / Votre bien devoue
Kerem G�mr�kc�
Latest Project: http://www.pro-it-education.de/software/deviceremover
Latest Open-Source Projects: http://entwicklung.junetz.de
-----------------------
"This reply is provided as is, without warranty express or implied."

From: Angel J. Hernández M. on 3 Feb 2009 00:49
Hi there,

I think the issue here might be that the GC (Garbage Collector) is
collecting your callbacks while your application still is using them. I
wrote a post last year about this

http://msmvps.com/blogs/angelhernandez/archive/2008/10/04/accessing-a-managed-object-from-unmanaged-memory-native.aspx

Hope this helps,

Cheers,


--
Angel J. Hern�ndez M
MCP,MCAD,MCSD,MCDBA
Microsoft MVP
http://msmvps.com/blogs/angelhernandez
***************************************************
Technical Solution Architect
http://www.customware.net




"Kerem G�mr�kc�" <kareem114(a)hotmail.com> wrote in message
news:#Zlhh1wgJHA.2384(a)TK2MSFTNGP04.phx.gbl...
> Hi,
>
> can someone please tell me why this class i created runs into
> a access violation after some while running it. It throws the exception
> after a unsepcified amount if time. Its pretty a pointer problem, but
> where do i have to check what?
>
> [StructLayout(LayoutKind.Sequential,CharSet=CharSet.Unicode)]
> public struct CWPSTRUCT
> {
> public IntPtr lParam;
> public IntPtr wParam;
> public int message;
> public IntPtr hwnd;
> }
>
> public enum HookType : int
> {
> WH_JOURNALRECORD = 0,
> WH_JOURNALPLAYBACK = 1,
> WH_KEYBOARD = 2,
> WH_GETMESSAGE = 3,
> WH_CALLWNDPROC = 4,
> WH_CBT = 5,
> WH_SYSMSGFILTER = 6,
> WH_MOUSE = 7,
> WH_HARDWARE = 8,
> WH_DEBUG = 9,
> WH_SHELL = 10,
> WH_FOREGROUNDIDLE = 11,
> WH_CALLWNDPROCRET = 12,
> WH_KEYBOARD_LL = 13,
> WH_MOUSE_LL = 14
> }
>
> public delegate int HookProc(int code, IntPtr wParam, IntPtr
> lParam);
>
> public delegate int HookProcCWPS(int code, IntPtr wParam, ref
> CWPSTRUCT cwps);
>
> [DllImport("kernel32.dll")]
> public static extern uint GetCurrentThreadId();
>
> [DllImport("user32.dll", SetLastError = true,CharSet =
> CharSet.Unicode)]
> public static extern IntPtr SetWindowsHookEx(HookType hook,
> HookProcCWPS callback,
> IntPtr hMod, uint dwThreadId);
>
> [DllImport("user32.dll", SetLastError = true, CharSet =
> CharSet.Unicode)]
> public static extern IntPtr SetWindowsHookEx(HookType hook,
> HookProc callback,
> IntPtr hMod, uint dwThreadId);
>
> [DllImport("user32.dll", CharSet = CharSet.Unicode)]
> public static extern int CallNextHookEx(IntPtr hhk, int nCode,
> IntPtr wParam,
> IntPtr lParam);
>
> [DllImport("user32.dll", CharSet = CharSet.Unicode)]
> public static extern int CallNextHookEx(IntPtr hhk, int nCode,
> IntPtr wParam,
> ref CWPSTRUCT cwps);
>
> [DllImport("user32.dll", SetLastError = true, CharSet =
> CharSet.Unicode)]
> public static extern bool UnhookWindowsHookEx(IntPtr hhk);
>
> public class DRWindowHelperClass
> {
> private IntPtr windowHandle;
> private IntPtr hhk;
> private Exception exception;
>
> public delegate void WindowMessageArrivedDelegate(ref Message
> WindowMessage);
> public event WindowMessageArrivedDelegate WindowMessageArrived;
>
> public DRWindowHelperClass(IntPtr WindowHandle)
> {
> this.windowHandle = WindowHandle;
> }
>
> public Exception LastException
> {
> set
> {
> this.exception = value;
> }
>
> get
> {
> return this.exception;
> }
> }
>
> public bool SetWindowsHook()
> {
> try
> {
> this.hhk =
> DRWin32APIClass.SetWindowsHookEx(DRWin32APIClass.HookType.WH_CALLWNDPROC,
> this.WndHookProcWPCS, IntPtr.Zero, DRWin32APIClass.GetCurrentThreadId());
>
> if (this.hhk == IntPtr.Zero)
> {
> throw new Win32Exception();
> }
>
> this.exception = new Win32Exception(0);
> return true;
> }
> catch (Exception err)
> {
> this.exception = err;
> return false;
> }
> }
>
> private int WndHookProcWPCS(int code, IntPtr wParam, ref
> DRWin32APIClass.CWPSTRUCT cwps)
> {
> if (code < 0)
> {
> return DRWin32APIClass.CallNextHookEx(IntPtr.Zero, code,
> wParam, ref cwps);
> }
> else
> {
> if (this.WindowMessageArrived != null)
> {
>
> Message m = new Message();
> m.HWnd = cwps.hwnd;
> m.LParam = cwps.lParam;
> m.WParam = cwps.lParam;
> m.Msg = cwps.message;
> m.Result = new IntPtr(0);
> this.WindowMessageArrived(ref m);
> }
>
> return DRWin32APIClass.CallNextHookEx(IntPtr.Zero, code,
> wParam, ref cwps);
> }
> }
>
> public bool RemoveWindowsHook()
> {
> try
> {
> if (DRWin32APIClass.UnhookWindowsHookEx(this.hhk) == true)
> {
> this.exception = new Win32Exception(0);
> return true;
> }
> else
> {
> throw new Win32Exception();
> }
> }
> catch (Exception err)
> {
> this.exception = err;
> return false;
> }
> }
>
> ~DRWindowHelperClass()
> {
> if (this.hhk != IntPtr.Zero)
> {
> DRWin32APIClass.UnhookWindowsHookEx(this.hhk);
> }
> }
>
> public IntPtr WindowHandle
> {
> get
> {
> return this.windowHandle;
> }
> }
> }
>
> Regards
>
> Kerem
>
> --
> --
> -----------------------
> Beste Gr�sse / Best regards / Votre bien devoue
> Kerem G�mr�kc�
> Latest Project: http://www.pro-it-education.de/software/deviceremover
> Latest Open-Source Projects: http://entwicklung.junetz.de
> -----------------------
> "This reply is provided as is, without warranty express or implied."

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