OpenEuphoria

Re: To Irv: about GraphApp

• Posted by Irv Mullins <irv at ELLIJAY.COM> Mar 10, 2000
• 479 views

----- Original Message -----
From: Mike Hurley <mike_hurley_2 at YAHOO.COM>
To: <EUPHORIA at LISTSERV.MUOHIO.EDU>
Sent: Friday, March 10, 2000 10:43 AM
Subject: To Irv: about GraphApp


> Irv-
> Where is the documentation for your GraphApp library?
> I d/l'd the demos but I can't find anything that looks
> like documentation (routine useage...etc.)

Hi Mike:

The documentation on using GraphApp is online at Loki's website,
http://www.cs.su.oz.au/~loki/graphapp/tutorial/
I have retained the same function names as used in Loki's C version,
so the translation to Euphoria is fairly easy. Note that Loki has functions
in both English and 'Merkun : setcolor() and setcolour(), for example, call
the
same function. I've implemented the US spelling for these.

One difference is in calling routines which require coordinates.
In C, they are passed via a function (rect)  that returns a pointer to a
structure,
which is then passed to the routine you are calling.
In Euphoria, all that is unnecessary, as you can just form the coordinates
as
a sequence {x1,y1,x2,y2} and pass them directly.

Example in C:

#include "graphapp.h"

void main(void)
{
  window w;

  w = newwindow("A Window",
                rect(50,50,150,200),
                StandardWindow);
  /* create your controls here */
  show(w);
  mainloop();
  /* close files and tidy up here */
}

Same thing in Euphoria:

include graphapp.e
constant w = newwindow("A Window",{50,50,150,200},StandardWindow)
-- create your controls here
show(w)
mainloop()

show() is always necessary.
mainloop() is the message processing part, so it is necessary if you expect
controls
to respond to events.

A second difference is in passing callbacks to your event handler functions:
setkeydown(w, call_back(routine_id("MyKeyPressedFunction")))
which is somewhat more complicated than the way it would be done in C, so
I usually include a wrapper function like the following:

function call(sequence routine)
return call_back(routine_id(routine))
end function

That makes it possible to call the event handler like this:
setkeydown(w,call("MyKeyPressedFunction"))

Write if you have questions.
Regards,
Irv