[webkit-dev] (no subject)
mf_software at mac.com
Sat Nov 4 23:35:30 PST 2006
I am seeing a strange problem with transparent PNG files in the
release version of Safari/WebKit on Max OS X 10.4.8 PPC:
I created a 1 pixel PNG image with color white and an alpha value of
When I display this in an IMG tag (or as a CSS background image) over
other content the other content does not appear lighter as expected
but more gray (not really darker).
When I use a CANVAS element to draw a white fill color with 60% alpha
the background is lightened as expected.
The current nightly build does not show this problem. By searching
for bugs related to PNG on <http://bugs.webkit.org> I couldn't find
anything relevant. Also Firefox 126.96.36.199+, Opera 9.02 and OmniWeb
5.5.1 show the expected color effect, i.e. lightening the background.
OTOH using a 1 pixel PNG with color black and an alpha of 50% works
exactly as expected, i.e. darkening the background for a shadow effect.
a) Was there a bug in WebKit causing this that got fixed for the
current nightlies? Or is this some unintended side effect and I need
to file a new bug to ensure that this stays fixed in the future?
b) Is there a workaround for the released version of WebKit (419.3)?
(Other than using a CANVAS element ;-)
A test page demonstrating the effect is here (the top transparent
area shows the problem):
this example. It essentially builds three layers: At the bottom some
text is created. Then (DIV id:"bgc1" z.index:1) some color areas are
created and in the top layer (DIV id:"bgc2" z-index:2) the
transparent testing areas are created.
Mike Fischer Softwareentwicklung, EDV-Beratung
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