Hi Mike,
I believe this is http://bugs.webkit.org/show_bug.cgi?id=3438 —
incorrect display of transparent 1x1 PNGs. Other than using canvas,
you can specify a background color with alpha for the div, for
example, style="background: rgba(255, 255, 255, 0.6)", use an opaque
fill and the opacity property, or use a PNG with bigger dimensions.
Cheers,
-- Mitz Pettel
On Nov 5, 2006, at 9:40 AM, Mike Fischer wrote:
Sorry, I forgot to add a subject!
Am 05.11.2006 um 08:35 schrieb Mike Fischer:
Hi!
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 approx. 60%.
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 1.5.0.7+, 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.
My questions:
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):
<http://home.fi-works.de/test/test-png-alpha.html>
Note that the testing area is built using JavaScript DOM methods
in 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.
Thanks!
Mike
--
Mike Fischer Softwareentwicklung, EDV-Beratung
Schulung, Vertrieb
Web: <http://homepage.mac.com/mike_fischer/index.html>
--
Mike Fischer Softwareentwicklung, EDV-Beratung
Schulung, Vertrieb
Web: <http://homepage.mac.com/mike_fischer/index.html>
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