Re: saving ICOs

[Keith Packard <keithp keithp com>]

Around 20 o'clock on Jun 29, Matthias Clasen wrote:

> I don't see how this is relevant, considering that RGBA is also
> not supported for classic X cursors.

The Xcursor library "supports" ARGB cursors on top of legacy X servers by
converting them to two-color+transparent through one of four different
algorithms:

	threshold	- black, white, transparent with no averaging
	median		- heckbert median cut with threshold transparency
	ordered		- 2x2 ordered dither using black, white, transparent
	diffuse		- Floyd Steinberg using black, white and transparent

I thought I'd left the default set to 'ordered', but it's currently set to 
threshold.

Within the X server, the 2x2 ordered dither is used for times when a 
hardware cursor is required and the hardware doesn't support ARGB cursors. 
A small dither was chosen to improve the reproduction of edges in what are 
generally very small objects.

This is relevant because a "good" cursor theme should also produce usable 
results when passed through the 2x2 dither algorithm.

You can play with these algorithms by adjusting environment variables for 
any application which loads cursors:

$ XCURSOR_DITHER=diffuse XCURSOR_SIZE=256 XCURSOR_CORE=true XCURSOR_THEME_CORE=true xsetroot -cursor_name gumby

-keith