Drawing Pixels in Plan9

note, May 27, 2023 on Mitja Felicijan's blog

I have started exploring Plan9's graphics capabilities. This is a hello world -alternative for drawing that draws a yellow square on a blue background.

More information:

Plan9 Howdy World!
// main.c
-#include <u.h>
-#include <libc.h>
-#include <draw.h>
-#include <cursor.h>
-
-void
-main()
-{
-  ulong co;
-  Image *im, *bg;
-  co = 0x0000FFFF;
-
-  if (initdraw(nil, nil, argv0) < 0)
-  {
-    sysfatal("%s: %r", argv0);
-  }
-
-  im = allocimage(display, Rect(0, 0, 300, 300), RGB24, 0, DYellow);
-  bg = allocimage(display, Rect(0, 0, 1, 1), RGB24, 1, co);
-
-  if (im == nil || bg == nil)
-  {
-    sysfatal("not enough memory");
-  }
-
-  draw(screen, screen->r, bg, nil, ZP);
-  draw(screen, screen->r, im, nil, Pt(-40, -40));
-
-  flushimage(display, Refnone);
-
-  // Wait 10 seconds before exiting.
-  sleep(10000);
-
-  exits(nil);
-}
-

And then compile with mk (mkfile below):

# mkfile
-</$objtype/mkfile
-
-RC=/rc/bin
-BIN=/$objtype/bin
-MAN=/sys/man
-
-main:
-	$CC $CFLAGS main.c
-	$LD $LDFLAGS -o main main.$O
-

And run with ./main. To exit the program, press Delete key (strange but this -is the alternative for Ctrl+C).

This is very cool indeed!