SAMPLE: KBHook2.exe Demonstrates Using a WH_KEYBOARD Hook

ID: Q81334

The information in this article applies to:

SUMMARY

KBHOOK2 is a file in the Software Library that contains sample code to demonstrate installing and using a system-wide WH_KEYBOARD keyboard filter function (otherwise known as a keyboard hook function). This code monitors the status of the CAPS LOCK key. Whenever the CAPS LOCK key is pressed, its status is displayed on the application's icon. Terminating the application removes the keyboard filter from the system.

KBHOOK2 updates the KBHOOK sample to use new functions provided by Windows 3.1.

MORE INFORMATION

The following file is available for download from the Microsoft Software Library: 

 ~ KBHook2.exe (size: 26280 bytes)
For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from
               Online Services
KBHOOK2 contains an application program, KEYAPP, and a dynamic-link library (DLL), KEYHOOK, that implements the keyboard filter function. The KEYHOOK DLL uses the new Windows 3.1 hook functions: SetWindowsHookEx, UnhookWindowsHookEx, and CallNextHookEx.

KEYAPP calls KEYHOOK to install the keyboard filter function and then makes itself iconic. Windows calls KEYHOOK each time a key is pressed. When the CAPS LOCK key is pressed, KEYHOOK posts a message to KEYAPP. KEYAPP processes the message by painting its icon to display the current state of CAPS LOCK. When KEYAPP is terminated, the KEYHOOK filter is removed from the system.

NOTE: Compiling this sample as is will fail with the error that the include file CONVDLL.INC cannot be found. To correct the problem, simply remove the line 

   INCLUDE CONVDLL.INC
from the LIBENTRY.ASM.

Additional query words: Keywords : kbfile kbsample kb16bitonly kbHook kbSDKPlatform kbGrpUser kbWinOS310

Last Reviewed: January 3, 1999