Joystick Plugin: adding throttle support to control volume

Mike Swieton <[email protected]> Fri, 10 Jan 2003 14:33:41 -0500

Newsgroups	gmane.comp.multimedia.xmms.devel
Message-ID	<[email protected]>

Earlier this morning it occured to me that I should be able to use the
throttle on my joystick to control the volume.

I wrote a quick hack to make it work, which I've attached. This does not patch
the GUI at all, and all constants are hardcoded. Sorry, but I do not have the
time to learn GTK to do it right, but maybe someone else here does.

Attached is a small C source file which has my changes. Insert the code into
the XMMS source file General/joystick/joy.c between the "}" and the "break;"
near line 258, to add support for the first joystick (The plugin supports two
joysticks). If you want a second joystick supported, you may paste it into the
line 291 (this line looks just like the first.

You'll have to do a bit of work to make this run. The directions are at the
top of the attached snippet.

This code is public domain.

Have fun, guys!

Mike Swieton
--
The perversity of the Universe tends towards a maximum.
	- O'Tool's Corollary of Finagle's Law

throttle.c (text/plain, 2.1 KB)

/* MKS - Begin throttle volume support */

/* THIS CODE IS PLACED IN THE PUBLIC DOMAIN.
 
   The original author is Michael Swieton, who may be contacted via email at
   [email protected]
 */

/* DIRECTIONS: *************************/
/* First: uncomment the printf statement at the bottom. This will help you find
 * out what axis number your throttle uses, and also its range. When you have
 * these numbers, I advise you to comment out that line again. Performance may
 * suffer if you don't.

 * Second: Set the range values below where noted. Note
 * that the maximum CAN be less that the minimum: it is the value at which you
 * want the throttle to represent full volume. */
/***************************************/

else if (js.number == 3)
{
	/* Range of the joystick's throttle */
	gint max=-13000;
	gint min= 13000;
	/* The current value of the throttle */
	gint val=js.value;
	/* The calculated volume */
	gint volume;
	gboolean swapped = FALSE;
	
	/* The maximums and minimums on my joystick seem
	 * rather arbitrary. These two if's simplify things
	 * by making minimum zero and maximum whatever and
	 * ensures that the reading is in the same relative
	 * position in the middle. We'll swap it back later
	 * if they are backwards, so the throttle changes
	 * things in the right direction. */
	if (max < min)
	{
		int tmp=max;
		max = min;
		min = tmp;
		swapped = TRUE;
	}

	if (min < 0)
	{
		max += -1*min;
		val += -1*min;
		min = 0;
	}

	/* Clip the throttle value */
	if (val < min) val = min;
	else if (val > max) val = max;
	
	/* Calculate and clip the final volume */
	volume = (int)((double)val/max * 100.0);
	if (volume < 0) volume = 0;
	else if (volume > 100) volume = 100;
	
	/* If our max and min are reversed, re-reverse it */
	if (swapped) volume = 100 - volume;
	
	/* Do it, mofo */
	xmms_remote_set_main_volume (joy_gp.xmms_session, (gint)volume);
}

/* The below line can be used to help determine what
 * axis number your throttle is and what its range is.
 * It is recommended that this code be commented out
 * before regular use, however */

/* printf ("Axis %d: Value: %d\n", js.number, js.value); */

/* MKS - End throttle volume support */