When to use PBMAIN vs. WINMAIN

[Dale Gillilan]

Under what circumstances would I want to use PBMAIN instead of WINMAIN (or, is it the other way around?)?

Thanks,
Dale

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[Lance Edmonds]

PBMAIN could be considered to operate similarly to a macro. That is, during compilation, the PBMAIN prototype actually gets replaced with a WINMAIN-like function prototype. Therefore, from the Operating System's perspective, there is no difference whether your app uses PBMAIN or WINMAIN.

However, you would use WINMAIN() instead of PBMAIN if you need to utilize the parameters that are accessable via WINMAIN: hInstance&, hPreInstance&, lpCmdLine, or nCmdShow&.

You can easily get the hInstance& handle from within your app with the GetModuleHandle() API, and COMMAND$ contains the commain-line parameters, so for these two, so the use of PBMAIN or WINMAIN is not really relevent.

The hPrevInstance& handle is not used in Win32, so that parameter is never going to be used in a real application anyway.

This leaves the nCmdShow& parameter...

This one is important for GUI applications: when an application is started, it should honor the initial ShowWindow() state that is directed by the nCmdShow& parameter.

For example, if you create a short-cut to an app, you can set the short-cut to "dictate" the app's initial window state for the app (Normal, Maximized, or Minimized). If your app ignores the nCmdShow& parameter, your app will not honor the window state it is "expected" to use.

Another example is an app that is started via the SHELL statement/function - SHELL has an optional parameter to dictate the initial window state, and this gets passed to the target app as the nCmdShow& parameter. Therefore, if the app is launched as Minimized, the poor app user should reasonably expect the app to actually _be_ minimized!

In my experience, programmers often make the "mistake" of ignoring the nCmdShow& parameter! (yes, II've been guilty of it too!)

Clear as mud?

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Paul Dwyer]

So Lance,

Does that mean that using PBMain is the same as ignoring the nCmdShow& parameter? or should we go and get this information some other way? You went to a great deal of trouble to explain it's function but not how the PBMAIN() function handles it.


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Paul Dwyer
Network Engineer
Aussie in Tokyo
(Paul282 at VB-World)

[Lance Edmonds]

Since PBMAIN does not make any parameters available to your code, you won't be able to access the nCmdShow& parameter. PBMAIN essentially "hides" these parameters from your code.

So in that sense, using PBMAIN is a good way to ignore the nCmdShow& parameter.

PBMAIN is often used in code on this BBS since it involves less typing and confusion, but it does not mean that it is always the best way to implement a GUI app that adheres to the MS GUI design guidelines.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Borje Hagsten]

Interesting knowledge, Lance. I always thought DIALOG SHOW MODAL, etc
took care of this automatically, but obviously not. Good to have
in mind in the future.

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[Paul Dwyer]

Ahhhh, so to conclude

"using PBMAIN is a good way to... " "make the 'mistake' of ignoring the nCmdShow& parameter" ??

Gee, I'm in a poor mood for a friday night

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Paul Dwyer
Network Engineer
Aussie in Tokyo
(Paul282 at VB-World)

[Guest]

Paul, sounds like you need to hop a train to Roppongi or Shibuya and party on!


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Ron

[Paul Dwyer]

Love to, but I live on the other side of town and transport here sux, If I need to get home after midnight then the taxi is about US$130
I'm trying to give up the "Get the first morning train home" lifestyle, must be getting old.



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Paul Dwyer
Network Engineer
Aussie in Tokyo
(Paul282 at VB-World)

[Charles Dietz]

Lance,

I have a desktop shortcut to an executable compiled by PowerBasic and using
PBMAIN. When I change the shortcut to 'run minimized' the request is honored.
Although nCmdShow& cannot be accessed by my program, it obviously is being
accounted for somehow.

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[Borje Hagsten]

Yes, just tested a simple app' myself. PBMAIN seems to do the job
like it should. Good!


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[Lance Edmonds]

Your observations are a behavior of Windows, not your code or PBMAIN per se.

The API doc's state that the nCmdShow should be honored unless the parent process provides the appropriate STARTUPINFO structure when launching the app (Subsequent executions of ShowWindow() can use any particular %SW_ style so desired). If the STARTUPINFO structure is not provided at startup, then nCmdShow should (must) be used for the first call to ShowWindow().

In other words, creating a shortcut per your test (or using SHELL from PB) does provide such a structure to Windows, and this dictates how the initial app window will be shown by Windows.

Actually, if your initial window is not resizable, maximizing it this way makes the window look terrible!

Hmmm... the more I think about it, the less clear it becomes about how to "force" an app to have to honor nCmdShow. Any ideas?

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Steve Hutchesson]

The basic code to start a window before a WinMain has no method
of receiving information from the operating system as such.

This is MASM for the pre-WinMain code,

start:
      invoke GetModuleHandle, NULL
      mov hInstance, eax

      invoke GetCommandLine
      mov CommandLine, eax

      invoke WinMain,hInstance,NULL,CommandLine,SW_SHOWDEFAULT
      invoke ExitProcess,eax

The parameters you receive in a WinMain are what the code before
it sends to it, the action is in the style SW_SHOWDEFAULT.

Code built in this manner honours the operating system choice of
starting minimised, normal or maximised.

A PBmain() is a lower level method that a WinMain and you can do
the same things in it, get the instance handle (start address in
memory), a command line if you need it and you can set the
ShowWindow() to the style you need directly in the code.

It is a good alternative as a WinMain is a 16 bit windows leftover
that has a dead previous instance parameter.

To answer you original question, there is not a lot of reason to
use a WinMain these days, you can get all of the information without
it.

Regards,

[email protected]

[This message has been edited by Steve Hutchesson (edited February 17, 2001).]