|Microsoft Windows Applications||Using GUIs from Third Party Tools|
This chapter explains how to use the 32-bit COBOL system to create 32-bit applications for running on Windows NT or Windows 95. It assumes you have a basic knowledge of the concepts involved in writing a Windows NT or Windows 95 program.
Windows NT and Windows 95 are referred to as 32-bit Windows in this chapter.
This chapter assumes you are using the 32-bit Win32 API. For details on writing applications for the 16-bit Windows API, see the chapter Microsoft Windows Applications.
Micro Focus offers the following approaches to programming 32-bit applications in COBOL for running on Windows:
The chapter Comparison of Methods for Creating User Interfaces explains the advantages and disadvantages of each of the above approaches.
To develop 32-bit applications for running on 32-bit Windows and Windows 95, you need the following:
The Win32 API uses the system linkage parameter-passing convention. This means that:
This convention is CALL-CONVENTION 74. See the chapter The COBOL Interfacing Environment in your Programmer's Guide to Writing Programs for details on the CALL-CONVENTION clause.
Every 32-bit Windows program is passed four startup values by the operating system. These values are obtained by using the PC_WIN_INIT call which is shown below. The method whereby the parameters are obtained from a Linkage Section is not supported.
local-storage section. 01 hIns pic x(4) comp-5. 01 hPrevInstance pic x(4) comp-5. 01 lpszCmdLine pointer. 01 nCmdShow pic x(4) comp-5. procedure division WINAPI. call "PC_WIN_INIT" using hInst hPrevInstance lpszCmdLine nCmdShow.
The following sections describe how to compile and link both existing character-based applications, and graphical user interface applications using the Win32 API to run on 32-bit Windows.
No special directives are needed when compiling applications for running under 32-bit Windows.
32-bit Windows systems provide a console subsystem for character-based applications. Therefore, no special support is required from the COBOL system.
If you do not need to specify any command-line compiler directives to compile your program, you can use the Cbllink link utility to compile and link your program in one step. See your Object COBOL User Guide for details on Cbllink.
To compile and link the sample program Tictac to run under 32-bit Windows with the shared run-time system:
The resulting program can be run just like any other 32-bit Windows application.
You can compile and link an application that has a graphical user interface using the Win32 API in one step by using Cbllink:
cbllink -g app.cbl
Alternatively, you can use Cblnames and Link32 to link your 32-bit Windows application:
cblnames /m app-entry-point app-obj-files link32 /out:app.exe /machine:i386 /subsystem:windows app-obj-files cbllds.obj mfrts32.lib crtdll.lib Win32-SDK-libraries
The sample programs Winhello and Wincalc demonstrate how to write
programs that can be compiled and linked to run natively on 16-bit or
32-bit Windows, depending on a value passed to the program when it is
compiled. The sample programs are compiled and linked to run on 32-bit
Windows if the value of the constant
32-bit is set to 1 when
the program is compiled. Because this value is set using a compiler
directive, you cannot use the Cbllink utility to perform the compilation
To compile the Winhello sample program to run on 32-bit Windows and link it using Cbllink:
cobol winhello constant 32-bit(1); cbllink -g winhello.obj
To compile the Winhello sample program to run on 32-bit Windows and link it using Link32:
cobol winhello constant 32-bit(1); cblnames /mwinhello winhello link32 /out:winhello.exe /machine:i386 /subsystem:windows winhello.obj cbllds.obj mfrts32.lib /crtdll.lib kernel32.lib user32.lib gdi32.lib
Linking the object module to form a .dll file is similar to linking to form an .exe file, but an additional step is required to create an export module used when linking the .dll file.
Consider the following COBOL program, windll.cbl:
procedure division using Return-String. move "Inside WINDLL" to Return-String exit program.
entry "WINDLL2" using Return-String. move "Inside WINDLL2" to Return-String exit program.
To compile and link this program using Cbllink, use the following command:
cbllink -d windll.cbl
A module definition .def file is automatically created and used when creating the .dll file.
Alternatively, a typical compile and link command using Link32 would be:
cobol windll; lib32 /out:windll.lib /def:windll.def /machine:i386 link32 /dll /out:windll.dll /entry:LibMain@12 /machine:i386 windll.exp windll.obj mfrts32.lib crtdll.lib
where windll.def contains the lines:
library windll description "a cobol dll for windows NT." data nonshared exports windll windll2
32-bit Windows systems do not require a Windows exit procedure (WEP) function in the module definition (.def) file for the .dll file. The LibMain function is now used for both initialization and termination of the .dll. For further details on 32-bit Windows definition files, see the documentation supplied with the Microsoft Win32 Software Development Kit.
If you use statically linked calls to a .dll file, you must create an import library for the .dll file and link this library into the calling program.
Consider the following main program, winexe.cbl:
procedure division. call "_ _windll" call "_ _windll2".
The double-underscore notation to force static linking is supported for backward compatibility with code written for the 16-bit COBOL system (see the description of the LITLINK directive). We recommend that you now use CALL-CONVENTION 8 to force static linking:
special-names. call-convention 2 is win32 call-convention 8 is static-dll.
procedure division. call static-dll "windll" call static-dll "windll2".
To create an import library on 32-bit Windows, use Lib32 as follows:
lib32 /out:windll.lib /def:windll.def /machine:i386
Then, when you link Winexe, you specify the library windll.lib on the link command line.
If you use dynamic calls, you do not need to supply any information to the linker. At run time, the run-time system module that handles dynamic calls first searches through loaded executable files to see if the required subprogram is already loaded. If it isn't, the disk is searched for an executable file whose filename matches the subprogram-name.
Therefore, if you use dynamic linking, the first call you make to the .dll file must use the name of the .dll file. For example:
procedure division. call "windll" call "windll2".
Use Animator V2 in the 32-bit COBOL system to debug your 32-bit applications for Windows. See your Object COBOL User Guide for details of Animator V2.
cobol main; cobol body; cbllink main body
There are some printer handling routines that are portable between the 32-bit COBOL systems running on Windows and OS/2. These routines are:
|PC_PRINT_FILE||Print a file|
|PC_PRINTER_CLOSE||Close a printer channel|
|PC_PRINTER_CONTROL||Send a printer command to a printer|
|PC_PRINTER_FREE_BMP||Free bitmap from memory|
|PC_PRINTER_INFO||Get printer information|
|PC_PRINTER_LOAD_BMP||Load bitmap into memory|
|PC_PRINTER_OPEN||Open a printer channel|
|PC_PRINTER_SET_COLOR||Set printer color|
|PC_PRINTER_SET_FONT||Set printer font|
|PC_PRINTER_WRITE||Write text to a printer|
|PC_PRINTER_WRITE_BMP||Write bitmap to a printer|
These routines are described in the Library Routines chapter of the Programming Guide to Writing Programs.
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|Microsoft Windows Applications||Using GUIs from Third Party Tools|