On 9/15/12 10:52 AM, Martin Hewitson wrote:
I'm not sure what the correct terminology is here. I have a text editor app
and the user can set the background color of the editor. The user can also
set the line length for wrapping. Past that length, I have been drawing a
shaded rect (in the text view subclass' -drawViewBackgroundInRect:). For the
shaded rect, I've been using NSColor's shadowWithLevel:. This works fine for
most colors, but obviously not for a black background. I suppose in some
cases I could highlightWithLevel and in others shadowWithLevel, but I don't
know how to distinguish between these cases. Is there something else I could
do to get a reasonable contrasting color?
You can create a monoChrome color from your background color and ask for its
-whiteComponent which will tell you how light it is. I use a category on NSColor
like this:
@implementation NSColor (lightness)
- (BOOL)isDarkerThan:(float)lightness
{
NSColor *monoColor = [self
colorUsingColorSpaceName:@"NSCalibratedWhiteColorSpace"];
return ([monoColor whiteComponent] < lightness);
}
@end
You can then query your color using a value between 0.0 and 1.0 and choose the
appropriate color for your shadow.
Regards
Markus
--
__________________________________________
Markus Spoettl
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