Problem with the keyboard hooks

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hemapriya hemapriya is offline Offline
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Problem with the keyboard hooks

 
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  #1
Apr 8th, 2006
hi all,
I am a student from India.I am developing an application that is a BHO that hooks the keyboard. I aiming to invoke some functionalities when some specific keys are pressed. Have the developed the code.Though my keyboard hook is getting installed, its not working! I found the reason to be some issue related to the place where i am getting a copy of the lParam of my HookProc and converting it to my KKHOOKSTRUCT structure. I dont know wats wrong in my code.It seems to be right. I am adding the hookproc and related declarations alone below:

C# Syntax (Toggle Plain Text) 
  1. #region Hook Variables
  2.  
  3. 		private delegate int KeyboardHookProcDelegate(int nCode, int wParam,ref int lParam); 
  4.  
  5. 		[MarshalAs(UnmanagedType.FunctionPtr)]
  6. 		private  KeyboardHookProcDelegate kbcatcher;
  7.  
  8.         public struct KeyboardHookStruct
  9. 		{
  10. 			public int vkCode;
  11. 			public int scanCode;
  12. 			public int flags;
  13. 			public int time;
  14. 			public int dwExtraInfo;
  15.  
  16. 		};
  17. 		private const int HC_ACTION = 0;
  18. 		private const int LLKHF_EXTENDED = 0x01;
  19. 		private const int LLKHF_ALTDOWN = 0x20;
  20. 		private const int VK_T = 0x54;
  21. 		private const int VK_P = 0x50;
  22. 		private const int VK_W	= 0x57;
  23. 		private const int VK_TAB = 0x9;
  24. 	                private const int VK_CONTROL = 0x11; 			private const int VK_ESCAPE = 0x1B;
  25.  
  26. 		private const int WH_KEYBOARD_LL=13;
  27.  
  28. 		private IntPtr KeyboardHandle = IntPtr.Zero;
  29. 		private static int mHook=0;
  30. 		#endregion
  31.  
  32. public static int KeyboardHookProc(int nCode, int wParam,ref int lParam) 
  33. 		{
  34. 			KeyboardHookStruct HookStruct;
  35. 			int ret = 0;
  36. 			long vkCode=0;
  37. 			int flag=0;			
  38. 			MessageBox.Show("inside HookProc");//S
  39. 			IntPtr pAlloc=IntPtr.Zero;
  40.  
  41. 			#region PtrStructure
  42. 			try
  43. 			{
  44. 				MessageBox.Show("Value of lParam:"+lParam.ToString()+"\nValue of wParam:"+wParam.ToString());//S
  45. 				try
  46. 				{
  47. 					pAlloc=Marshal.AllocHGlobal(Marshal.SizeOf(ret)*5);
  48. 					if(pAlloc!=IntPtr.Zero)
  49. 					{
  50. 						MessageBox.Show("Allocation done");
  51. 					}
  52. 					else
  53. 						MessageBox.Show("no allocation");
  54. 				}
  55. 				catch(Exception e)
  56. 				{
  57. 					MessageBox.Show(e.ToString());//S
  58. 				}
  59.  
  60. 				//IntPtr pDest=pAlloc;
  61. 				try
  62. 				{
  63. 					CopyMemory(pAlloc,lParam,Marshal.SizeOf(ret)*5);
  64. 					MessageBox.Show("memory copied");
  65. 				}
  66. 				catch(Exception e)
  67. 				{
  68. 					MessageBox.Show(e.ToString());//S
  69. 				}
  70. 				try
  71. 				{
  72. 					HookStruct = ((KeyboardHookStruct) Marshal.PtrToStructure(pAlloc, typeof(KeyboardHookStruct)));
  73. 					MessageBox.Show("conversion done");//S
  74. 					vkCode= HookStruct.vkCode;
  75. 					flag = HookStruct.flags;
  76. 					MessageBox.Show("Value of vkCode:"+vkCode.ToString()+"\nValue of flag:"+flag.ToString());//S
  77. 				}
  78. 				catch(Exception e)
  79. 				{
  80. 					MessageBox.Show(e.ToString());//S
  81. 				}
  82.  
  83. 			}
  84. 			catch(Exception e)
  85. 			{
  86. 				MessageBox.Show(e.ToString());//S
  87. 			}
  88. 			finally
  89. 			{
  90. 				Marshal.FreeHGlobal(pAlloc);
  91. 				pAlloc=IntPtr.Zero;
  92. 			}
  93. 			#endregion
  94.  
  95. 			#region KeyCheck
  96. 			if(nCode==HC_ACTION)
  97. 			{
  98. 				MessageBox.Show("inside nCode==HC_ACTION");//S
  99. 				//System.Windows.Forms.Keys  KeyPressed = (Keys)wParam.ToInt32();
  100.  
  101. 				// Insert + T  OR Alt + T
  102. 				if(vkCode == VK_T )
  103. 				{
  104. 					MessageBox.Show(" found T ");
  105. 					if((GetAsyncKeyState(VK_CONTROL) & 0x8000) != 0)
  106. 					{
  107. 						MessageBox.Show("Play");
  108. 						ret=1;
  109. 					}
  110. 					else if((flag & LLKHF_ALTDOWN)!=0)
  111. 					{
  112. 						MessageBox.Show("Stop");
  113. 						ret=1;
  114. 					}
  115. 					else
  116. 						MessageBox.Show("Neither Ctrl nor Alt");
  117. 				}
  118. 				else if(vkCode == VK_P)
  119. 				{
  120. 					MessageBox.Show(" found P ");
  121. 					if((GetAsyncKeyState(VK_CONTROL) & 0x8000) != 0)
  122. 					{ //Insert + P
  123. 						MessageBox.Show("pause");
  124. 						ret = 1 ;
  125. 					}
  126. 					else
  127. 						MessageBox.Show("not ctrl");
  128. 				}
  129. 				else if(vkCode == VK_W) 
  130. 				{
  131. 					MessageBox.Show(" found W ");
  132. 					if((GetAsyncKeyState(VK_CONTROL) & 0x8000) != 0)
  133. 					{
  134. 						// Alt + S
  135. 						MessageBox.Show("Save");
  136. 						ret = 1 ;
  137. 					}
  138. 				}
  139. 				else
  140. 					MessageBox.Show("none of the conditions satisfied");
  141.  
  142. 				/*/	CopyMemory(HookStruct,lParam,sizeof(HookStruct);
  143. 					if(IsHooked(HookStruct))
  144. 						{
  145. 							MyKeyboardProc=1;
  146. 						}*/
  147.  
  148. 				//	MyKeyboardProc=1;
  149. 			}
  150. 			#endregion
  151.  
  152. 			//#region CallNextHookProc call
  153. 			if( ret == 0 )
  154. 			{
  155. 				ret = CallNextHookEx(mHook,nCode,wParam,lParam);
  156. 			}
  157. 		//	#endregion
  158. 			return ret;
  159. 		}
The problem is that none of the keys are detected.The values for lParam and wParam are not the same. Some problem with the way the structure getting copied.

I have not used the wParam anywhere.Should i?

This is a global hook.Actually i want the hook only when IE window is in focus. How to do this?

Please help me to solve this.This is my project in C# and window hooks is very new to me.


Thanking u.
Regards,
hema
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Re: Problem with the keyboard hooks

 
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  #2
Jul 29th, 2006
hi hema, did u read the documentation of Hooking in MSDN
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A global hook monitors messages for all threads in the same desktop as the calling thread. A thread-specific hook monitors messages for only an individual thread. A global hook procedure can be called in the context of any application in the same desktop as the calling thread, so the procedure must be in a separate dynamic-link library (DLL) module. A thread-specific hook procedure is called only in the context of the associated thread. If an application installs a hook procedure for one of its own threads, the hook procedure can be in either the same module as the rest of the application's code or in a DLL. If the application installs a hook procedure for a thread of a different application, the procedure must be in a DLL
http://msdn.microsoft.com/library/de...abouthooks.asp

you can get more information from this example
http://www.codeproject.com/csharp/gl...mhook.asp#xxxx

Ahmed Samieh
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Lord Soth Lord Soth is offline Offline
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Re: Problem with the keyboard hooks

 
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  #3
Aug 5th, 2006
Hi,

I doubt that you can create that separate hook dll with managed code but you can create the app managed and the dll native code (C++, Delphi).

Loren Soth
Best regards,
Loren Soth

Crimson K. Software _________________________________________________________________ Crimson K. Blog
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