Q188404: HOWTO: Use API Calls to Detect Other Running Applications

Article: Q188404
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b,5.0,5.0a
Operating System(s): 
Keyword(s): kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp500a kbDSupport
Last Modified: 07-OCT-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a 
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SUMMARY
=======

At times it is desirable to determine what other applications or background
processes are executing. This article describes how to use Windows API calls to
determine what applications are running concurrently with a Visual FoxPro
session or application.

MORE INFORMATION
================

Under certain circumstances, it is desirable to determine whether other
applications, or multiple instances of a application are executing. You can use
Windows API calls to determine what applications are executing at any given
time. The code snippet, listed below, illustrates use of Windows API functions
to determine what applications are currently executing.

Create a program called Enumwins.prg and type in the following code:

Sample Code
-----------

     LOCAL awin_apps, vfp_handle, ln_current_window,ln_window_count
     * Dimension array awin_apps to store running apps
     DIMENSION awin_apps[1]
     * Initialize variable to store handle for current application
     vfp_handle=0
     * Declare API Functions
     DECLARE INTEGER FindWindow ;
        IN win32api ;
        INTEGER nullpointer, ;
        STRING cwindow_name
     DECLARE INTEGER GetWindow ;
        IN win32api ;
        INTEGER ncurr_window_handle, ;
        INTEGER ndirection
     DECLARE INTEGER GetWindowText ;
        IN win32api ;
        INTEGER n_win_handle, ;
        STRING @ cwindow_title, ;
        INTEGER ntitle_length
     * End of API function declarations
     * Get handle for current application
     vfp_handle=findwindow(0,_SCREEN.CAPTION)
     * Store handle of current app to a variable
     ln_current_window=vfp_handle
     * Initialize a count variable used to dimension array of running apps
     ln_window_count=0
     DO WHILE ln_current_window>0
        *  Initialize variable to store application title
        lc_window_title=SPACE(255)
        * Call to GetWindowText to fetch window caption
        ln_length=getwindowtext(ln_current_window, ;
           @lc_window_title,LEN(lc_window_title))
        * Note that the lc_window_title variable is used as a buffer to
        * receive text from the call to GetWindowText
        IF ln_length>0
           lc_window_title=STRTRAN(TRIM(lc_window_title),CHR(0),"")
        ELSE
           lc_window_title=""
        ENDIF
        IF ln_current_window>0 .AND. !EMPTY(lc_window_title)
           * Increment the window count and re-dimension the array of running
           * applications
           ln_window_count=ln_window_count+1
           DIMENSION awin_apps(ln_window_count)
           awin_apps[ln_Window_Count]=lc_window_title
        ENDIF
        * Call to GetWindow to fetch handle of running applications.
        ln_current_window=getwindow(ln_current_window,2)
     ENDDO
     CREATE TABLE runapps (appname m)
     IF ALEN(awin_apps,1)>0
        SELECT runapps
        APPEND BLANK
        FOR i=1 TO ALEN(awin_apps,1)
           REPLACE appname WITH awin_apps[i]+CHR(13) ADDITIVE
        NEXT
     ENDIF
     MODIFY MEMO appname NOEDIT

The application stores the names of all executing applications in the memo field
of the table Runapps.dbf.
(c) Microsoft Corporation 1999, All Rights Reserved.
Contributions by John Desch, Microsoft Corporation


Additional query words:

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Keywords          : kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp500a kbDSupport 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP500a
Version           : WINDOWS:3.0,3.0b,5.0,5.0a
Issue type        : kbhowto

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