Programming Forums > Application Development > C#

MisterPoppy · Aug 2nd, 2006, 2:37 PM

Hello everyone. I've got a problem. I'm trying to simulate mouse clicks but i get this "PInvokeStackImbalance was detected" exception. I've searched google but didn't find any answer.
Here's the code:

(Toggle Plain Text)

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);

        private const int MOUSEEVENTF_LEFTDOWN = 0x02;
        private const int MOUSEEVENTF_LEFTUP = 0x04;
        private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        private const int MOUSEEVENTF_RIGHTUP = 0x10;       

        



        private void button1_Click(object sender, EventArgs e)
        {
            IntPtr firefoxHandle = FindWindow("MozillaWindowClass", "****** - Mozilla Firefox");
           
            if (firefoxHandle == IntPtr.Zero)
            {
                MessageBox.Show("Could not found the window!");
                return;
            }

            SetForegroundWindow(firefoxHandle);
            /*
            int X = 710;
            int Y = 445;*/
            int X = Cursor.Position.X;
            int Y = Cursor.Position.Y;
            mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, X, Y , 0, 0);                
      
        }

It's meant to click, for example, a button on a webpage in firefox.
�
Thanks alot for the help, in advance.

Dameon · Aug 2nd, 2006, 3:08 PM

You're parameter list for mouse_event is incorrect.

It's a common enough mistake in this case. Often times one will translate an API signature from an example given in C++ or VB. In VB, a Long is 4 bytes. In C++, the parameters are listed as DWORD (a typedef for unsigned long) which is 4 bytes. In C#, a long is 8 bytes. In short, you are passing twice as much data to the function as it expects. Note also that Windows API functions are invoked with stdcall, meaning that the called function cleans up the stack when returning. The exception you are getting is a handy warning from Pinvoke that the stack pointer isn't in the same position as before you called the function. Because your code is advancing it twice as much as the called function is unwinding it.

The type you are looking for to match a DWORD is Int32 or just int. No need to bother with .Net's terrible support for unsigned values in this case since the range you will be using with this particular function is narrow.

MisterPoppy · Aug 2nd, 2006, 4:27 PM

It worked. I replaced

(Toggle Plain Text)

public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);

with:

(Toggle Plain Text)

public static extern void mouse_event(Int32 dwFlags, Int32 dx, Int32 dy, Int32 cButtons, Int32 dwExtraInfo);

Thanks alot Dameon

!

kurifu · Aug 5th, 2006, 5:20 PM

You should check our the website www.pinvoke.net great resource for looking up signatures.

Aug 2nd, 2006, 2:37 PM	#1
MisterPoppy Newbie Join Date: Apr 2006 Location: Sweden Posts: 13 Rep Power: 0	PInvokeStackImbalance was detected. Hello everyone. I've got a problem. I'm trying to simulate mouse clicks but i get this "PInvokeStackImbalance was detected" exception. I've searched google but didn't find any answer. Here's the code: (Toggle Plain Text) [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo); private const int MOUSEEVENTF_LEFTDOWN = 0x02; private const int MOUSEEVENTF_LEFTUP = 0x04; private const int MOUSEEVENTF_RIGHTDOWN = 0x08; private const int MOUSEEVENTF_RIGHTUP = 0x10; private void button1_Click(object sender, EventArgs e) { IntPtr firefoxHandle = FindWindow("MozillaWindowClass", "****** - Mozilla Firefox"); if (firefoxHandle == IntPtr.Zero) { MessageBox.Show("Could not found the window!"); return; } SetForegroundWindow(firefoxHandle); /* int X = 710; int Y = 445;/ int X = Cursor.Position.X; int Y = Cursor.Position.Y; mouse_event(MOUSEEVENTF_LEFTDOWN \| MOUSEEVENTF_LEFTUP, X, Y , 0, 0); } [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo); private const int MOUSEEVENTF_LEFTDOWN = 0x02; private const int MOUSEEVENTF_LEFTUP = 0x04; private const int MOUSEEVENTF_RIGHTDOWN = 0x08; private const int MOUSEEVENTF_RIGHTUP = 0x10; private void button1_Click(object sender, EventArgs e) { IntPtr firefoxHandle = FindWindow("MozillaWindowClass", "***** - Mozilla Firefox"); if (firefoxHandle == IntPtr.Zero) { MessageBox.Show("Could not found the window!"); return; } SetForegroundWindow(firefoxHandle); /* int X = 710; int Y = 445;*/ int X = Cursor.Position.X; int Y = Cursor.Position.Y; mouse_event(MOUSEEVENTF_LEFTDOWN \| MOUSEEVENTF_LEFTUP, X, Y , 0, 0); } It's meant to click, for example, a button on a webpage in firefox. � Thanks alot for the help, in advance.

Aug 2nd, 2006, 3:08 PM	#2
Dameon Troll Join Date: Apr 2005 Location: Texas Posts: 732 Rep Power: 4	You're parameter list for mouse_event is incorrect. It's a common enough mistake in this case. Often times one will translate an API signature from an example given in C++ or VB. In VB, a Long is 4 bytes. In C++, the parameters are listed as DWORD (a typedef for unsigned long) which is 4 bytes. In C#, a long is 8 bytes. In short, you are passing twice as much data to the function as it expects. Note also that Windows API functions are invoked with stdcall, meaning that the called function cleans up the stack when returning. The exception you are getting is a handy warning from Pinvoke that the stack pointer isn't in the same position as before you called the function. Because your code is advancing it twice as much as the called function is unwinding it. The type you are looking for to match a DWORD is Int32 or just int. No need to bother with .Net's terrible support for unsigned values in this case since the range you will be using with this particular function is narrow. __________________ MD5(sig) = bcef75433db02e9ad9bf81d6f7c5c270 Last edited by Dameon; Aug 2nd, 2006 at 3:19 PM.

Aug 2nd, 2006, 4:27 PM	#3
MisterPoppy Newbie Join Date: Apr 2006 Location: Sweden Posts: 13 Rep Power: 0	It worked. I replaced (Toggle Plain Text) public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo); public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo); with: (Toggle Plain Text) public static extern void mouse_event(Int32 dwFlags, Int32 dx, Int32 dy, Int32 cButtons, Int32 dwExtraInfo); public static extern void mouse_event(Int32 dwFlags, Int32 dx, Int32 dy, Int32 cButtons, Int32 dwExtraInfo); Thanks alot Dameon !

Aug 5th, 2006, 5:20 PM	#4
kurifu Expert Programmer Join Date: Jul 2004 Location: Halifax, Nova Scotia (Canada) Posts: 784 Rep Power: 5	You should check our the website www.pinvoke.net great resource for looking up signatures. __________________ Clifford Matthew Roche <geek@cliffordroche.com> Web Hosting: http://www.crd-hosting.com Consulting: http://www.crdev-consulting.com

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Programming Forums > Application Development > C#

PInvokeStackImbalance was detected.