Juergen Spitzmueller wrote:
> Angus Leeming wrote:
>> <shrug>dunno</shrug>
>> You could perhaps parse /usr/lib/X11/rgb.txt (location may vary). It has
>> entries of the form:
>> 255 250 250 snow
>> 248 248 255 ghost white
>> but really, I think that that is overkill.
>
> Don't get me wrong, I don't wanna do art. I'm just wondering if we could
> automagically decide if a user choses a button color whether we need a
> rather white or rather black label text. Let's say a user choses a
> 240,255,255 (dark blue) background, then white would be better for label
> text than black. But probably that's not possible.
Next to impossible in an RGB colourspace, but quite easy in an HSV one.
Eg:
RGBColor getConjugate(RGBColor const & rgb)
{
HSVColor hsv = HSVColor(rgb);
// Assume this color is red
// changing hsv.s, "saturation", will take you from near white (hsv.s = 0)
// to red (hsv.s = 1).
// changing hsv.v, "value", will take you from black (hsv.v = 0) to
// red (hsv.v = 1).
// So, if 'v' is > 70% adjust 's', else adjust 'v' seems like a
// reasonable strategy.
if (hsv.v > 0.7)
hsv.s = ...;
else
hsv.v -= 0.5;
return RGBColor(hsv);
}
--
Angus
