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video_displaygamma(3)		 Arcan Lua API		 video_displaygamma(3)

NAME
       video_displaygamma - get	or set the gamma ramps for a display

SYNOPSIS
       [tbl or boolean]
       video_displaygamma( dispid or vid, tbl, index )

DESCRIPTION
       Some  hardware  platforms  and  displays	 supports hardware accelerated
       gamma and color correction. This	function is used to both test for  the
       availability  of	such features and to change or query the currently ac-
       tive values.  dispid  is	either 0 for the default display, or  provided
       as  a  hotplug  event in	the applname_display_event handler. It is also
       possible	to use a vid  instead, if the connected	 client	 supports  the
       extended	 color	ramp  subprotocol  and has been	granted	permissions to
       synch such tables by setting the	permission bit through	target_flags
       TARGET_ALLOWCM .	In this	case, tbl  may also contain an 'edid' key with
       the  display  ID	, and the optional index  (default=0) display subindex
       will be used.  Clients  that  enable  this  feature  will  trigger  the
       'proto_change'  event  and may start generating 'ramp_update' events in
       the event of suggested ramp updates.

       If the optional tbl  argument is	not set,  the  gamma  tables  will  be
       queried,	 and  returned	as  a number-indexed table with	the individual
       channels	(r, g, b) packed as separated planes (tbl[1] = r,  tbl[#tbl/3]
       = g, tbl[#tbl/3*2] = b) as numbers in the 0.0 to	1.0 range.

       If  the optional	tbl  argument is set, the gamma	tables for the display
       will be updated with new	values and the function	returns	true or	 false
       depending  on if	the device accepted the	tables or not. Mismatching ta-
       bles may	be a terminal state transition,	so only	use tables  that  come
       from a previous call to video_displaygamma .

EXAMPLE
       function	video_displaygamma0()
	     local tbl = video_displaygamma(0);
	     if	(tbl and #tbl >	0) then
		   for i=1,#tbl/3 do
			 tbl[i]	= tbl[i] * 0.1;
		   end
		   video_displaygamma(0, tbl);
	     else
		   warning("display does not support gamma tables");
	     end
       end

SEE ALSO:
vidsys				  April	2025		 video_displaygamma(3)

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