Re: Rotating pixmap

[Mihai BAZON <mbazon websci ro>]

Hmm...

If I were you I would be worried about the other arguments :)
But here it is: (I didn't try it, but I'm sure I'm right)

  GdkPoint* points;
  points = (GdkPoint*)malloc(nr_pts * sizeof(GdkPoint));
  // init points, e.g.
  for (i = 0; i < nr_pts; i++) {
     init_point(points + i);
  }
  gdk_draw_polygon(drawable, gc, 1 /*filled*/, points, nr_pts);

I think you don't have to give it points for a closed polygon (normally
it should close the polygon, i.e. for a rectangle you give it 4 points,
not 5 -- the fifth would be the first).


Good luck!

PS: better consider using libtool for vector drawing

/*   -*- Mishoo -*-         In the beginning there was nothing,
 *  mishoo websci ro      which exploded.   (The Big Bang Theory)  */

On Fri, 11 May 2001, Marco Quezada wrote:

> Thanks all for your input.
>
> Well, unfortunately I can't animate it before hand because the arrow's heading
> must be updated in realtime as the user flies a simulated aircraft.
>
> I was thinking about drawing it as just a couple of lines. I figured the
> easiest way to do this was to define a set of points and use gdk_draw_polygon
> but I have been unsuccesful with it. Does anyone have or know of an example on
> using this function? How must the *points argument be declared? is it an array?
>
> Thanks.
>
> Mihai BAZON wrote:
>
> > You can use ImageMagick (www.imagemagick.org) -- highly portable, can do
> > many transformations on a bitmap, knows many file formats, etc.
> >
> > However, I think it's too much to require users of your program to have
> > imagemagick installed, only for this problem.  If your animation does
> > not depend on user (i.e. you already know that it will spin like a
> > compass) -- why not render it before, and when the program runs only
> > draw it (avoid useless computations)?
> >
> > Cheers,
> >
> > /*   -*- Mishoo -*-         In the beginning there was nothing,
> >  *  mishoo websci ro      which exploded.   (The Big Bang Theory)  */
> >
> > On 10 May 2001, Havoc Pennington wrote:
> >
> > > Marco Quezada <mquezada nlxcorp com> writes:
> > > > I have a defined a draing area inside which I display a small icon (an
> > > > arrow). The icon is a pixmap which gets loaded with
> > > > gdk_pixmap_create_from_xpm_d and such. The XPM of the arrow shows the
> > > > arrow pointing to the right. I would like to show the arrow rotating
> > > > like a compass. Is it possible to rotate the pixmap when drawing it onto
> > > > the drawing area?
> > >
> > > No. (That is, GTK provides no way. You can write your own code, but
> > > it's not trivial.)
> > >
> > > Havoc
> > >
> > > _______________________________________________
> > > gtk-app-devel-list mailing list
> > > gtk-app-devel-list gnome org
> > > http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
>
> --
> Marco Quezada
> Aerospaceo Engineero
> NLX Corporation
> 22626 Sally Ride Dr.
> Sterling, VA, 20164
> mquezada nlxcorp com
> 703-234-2100 x1028
> http://www.nlxcorp.com