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Black on transparent diagrams don't work with a black background.

Black on transparent diagrams don't work with a black background.

Posted Apr 12, 2007 12:53 UTC (Thu) by Duncan (guest, #6647)
Parent article: A peek at the DragonFly Virtual Kernel (part 1)

Observation: Posting a diagram with black text on a transparent background
isn't such a good idea on a web site that allows the user to set the
background black as well. As it happens, I MUCH prefer light foregrounds
with dark backgrounds, and attempting to view that diagram on a black
background just does /not/ work! (I ended up dragging the diagram out of
konqueror to the desktop, where it was saved. Then I could see what it
was as soon as I moused over it (without even opening it), since I got the
infotip including a thumbnail with a lighter background.)

A UI general rule of thumb, and this DEFINITELY applies to the web, where
users have all sorts of default preferences, is that if you set one of
foreground or background color, ALWAYS set the other as well. Or where
possible, simply leave everything at the default, which the user may well
have set to match his own preferences already. Of course, the closest one
could get to the latter with a diagram such as the one used here would be
transparent, and XOR, but I'm not sure png supports XOR, tho it definitely
support transparent. The other alternative is as I said, to set BOTH
foreground and background, thus NOT making use of transparency except
where the remaining colors are varied enough that substitution of any
color for the transparency won't obscure the information an attempt is
being made to present.


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