DOCUMENT:Q79871 05-NOV-1999 [vbwin] TITLE :Applications That Run with or Without Pen Extensions PRODUCT :Microsoft Visual Basic for Windows PROD/VER::1.0 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows for Pen Computing, version 1.0 ------------------------------------------------------------------------------- SUMMARY ======= Typically, applications that are developed for Microsoft Windows for Pen Computing do not run unless the pen extensions are installed in memory. The reason for this is that these applications are implicitly linked to PENWIN.DLL. When a user runs an application that is implicitly linked to PENWIN.DLL on a system where the pen extensions are not installed, the application fails to load with the following error message: File Error Cannot find PENWIN.DLL The SNOOP sample application, provided with the Microsoft Windows for Pen Computing in the Windows Software Development Kit (SDK), is an example of an application that runs only when the pen extensions are installed. Applications can be designed to run in either environment, under Windows with or without the pen extensions. The HFORM sample application, also provided with the Windows for Pen Computing in the Windows SDK, is an example of this type of application. This article lists the steps required to create an application that runs in either environment; this article also lists other sample applications that do not implicitly link with PENWIN.DLL. MORE INFORMATION ================ An application that does not implicitly link with PENWIN.DLL can use the pen API functions when they are available and can run in the Windows environment when the pen extensions are not available. The application must not reference any of the pen functions directly. At run time, the application must retrieve the handle to PENWIN.DLL and explicitly load any functions that the application will use. The following four steps detail how an application that is not implicitly linked to PENWIN.DLL would load and use the Recognize function: 1. Prototype the Recognize function in the application's header file as follows: REC (FAR PASCAL *lpfnRecognize)(LPRC); 2. In the application's initialization, use GetSystemMetrics() to see if the pen extensions are installed. If the value returned from this function is zero, the pen extensions are not installed. Otherwise, the return value is the handle to PENWIN.DLL. 3. If the extensions are installed, use GetProcAddress() to retrieve the address of the Recognize function. A NULL return value indicates an error. The following fragment demonstrates this step: if (lpfnRecognize = GetProcAddress(hPenWinDLL, "Recognize")) 4. Finally, call the function using the procedure address, as follows: lpfnRecognize(&rc); As noted above, the HFORM sample application provided with the Windows for Pen Computing SDK demonstrates the process detailed in this article. REPAINT, HOTSPOTS, and PRESSURE are additional sample applications in the Software/Data Library that demonstrate this method. The articles that describe these sample applications can be found by searching this Knowledge Base for the name of the desired sample application. Additional query words: 1.00 ====================================================================== Keywords : Technology : kbWinPenSearch kbZNotKeyword3 kbWinPen100 Version : :1.0 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1999.