Drawing Pixels in Plan9

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:

• draw.h header file contains all the drawing functions
• draw man page has a bit more digestable descriptions of the draw functions
• graphics man page has a bit more digestable descriptions of the graphics functions
• all man pages can be a valuable resource for learning about the system

// 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!