Re: [AD] About the X-Window version.

[Shawn Hargreaves <shawn@xxxxxxxxxx>]

Peter Wang <tjaden@xxxxxxxxxx> writes:
> I guess what I'm asking is, is it possible for a program to connect to the 
> X server without opening a window, then open it during set_gfx_mode?
> If not, would it be viable for X/Allegro to not connect until set_gfx_mode 
> called for the first time?

(coming up: a wild guess from someone who has never done any X coding :-)

The trouble with opening a window during set_gfx_mode(), is that then you'd 
probably want to destroy it again during set_gfx_mode(GFX_TEXT), and that 
would lead to a new window being created for each new graphics mode, and 
therefore manual positioning window managers would require you to repeat the 
positioning every time the program changed video mode. Not good!

I suppose it would be possible to only create the window the first time 
set_gfx_mode() is called, but that leads to an inconsistency in that the 
program state before your first call to set_gfx_mode() is totally different 
to after you call set_gfx_mode(GFX_TEXT), and I don't think that is such a 
good thing.

Creating one a window at startup is consistent with how the Windows version 
behaves (although with that, the window isn't actually visible until you set 
a graphics mode, but it does show up in the task bar). Part of the rules for 
being portable are that you are no longer allowed to do anything important 
_without_ being in a graphics mode (because not all systems have any other 
way to be, for example Windows apps don't exist at all unless they have a 
window to be inside of).

The current behaviour is only a problem for apps that quit after printing an 
error message to the console, but on Windows, that is handled by overriding 
allegro_message() to bring up a dialog box. Unfortunately we don't have any 
such easy way to do this in X (it would be silly to require a whole toolkit 
just for displaying error messages!) but in the long run, I think that might 
be the best way to fix this. Among other things, a graphical allegro_error() 
would be useful for people who launch programs from a menu or graphical file 
manager, since otherwise they don't have any way to see the error output.

And automatically opening windows isn't a problem for true commandline apps 
like the dat archiver, because those use the SYSTEM_NONE driver instead 
of SYSTEM_XWINDOWS, which bypasses the X code entirely.


--
Shawn Hargreaves - shawn@xxxxxxxxxx - http://www.talula.demon.co.uk/
"A binary is barely software: it's more like hardware on a floppy disk."