[slang-users] Refresh problem

[John E. Davis]

On Wed, 28 Jun 2006 19:57:55 +0200, leslie.polzer at gmx.net said:
>No, nothing like that.  The relevant code snippet is very simple:
>
>---
>        SLtt_set_color(200, NULL, "white", "cyan");
>
>        SLsmg_set_color(200);
>
>        SLsmg_gotorc(1, 1);
>        SLsmg_write_nstring(NULL, 10);
>
>        SLsmg_gotorc(1, 1);
>        SLsmg_printf("%s", "some string");
>
>        SLsmg_refresh();

The SLtt_set_color function is a "setup" type of function that should
not be called everytime you want to update the screen.  As you know,
it is a function that associates a foreground/background color with a
color object (an integer--- 200 in this case).  Note that it is part
of the lower-level SLtt interface--- not the higher-level SLsmg
interface.  When you call SLtt_set_color, it informs the SLsmg
interface that color object 200 has been changed causing SLsmg to
invalidate the display.  This is the effect that you are seeing.

I may change the code in SLtt_set_color to do nothing if the
specified color object already has the requested attributes.  However,
I encourage you to move the call to SLtt_set_color to some sort of
initialization function that you call once.  For example, in main use:

    int main (...)
    {
       /* Setup color objects */
       SLtt_set_color (200, NULL, "white", "cyan");
          .
	  .
       
       main_loop ();
       return 0;
    }


    void main_loop (void)
    {
       while (1)
         {
	       .
	       .
	    draw_screen ();
	    SLsmg_refresh ();
	       .
	       .
	 }
    }
    
--John