Stefan Schimanski wrote:
Am 15.10.2007 um 22:46 schrieb Abdelrazak Younes:
Stefan Schimanski wrote:
This should explain it on Mac:
http://michelf.com/weblog/2006/subpixel-antialiasing-achilles-heel/
Here is the important part:
That said, I think Quartz is pretty smart because subpixel
antialiasing works on semitransparent backgrounds, like menus
pulling out from the menu bar. It implements some sort of gradual
degradation of the subpixels. For instance, if the background on
which it draw text has a transparency of 50%, half of each subpixel
value will be standard antialiasing, the other half being subpixel
antialiasing.
So if an application draws in an offscreen buffer with a transparent
background � surprise! � no subpixel antialiasing. Until Apple
implements some kind of aRaGaB compositor, application developers
will have to choose between a fast application with off-screen
rendering or subpixel antialiasing, but not both.
Indeed... That's too bad! I was pretty proud of this solution :-(
It is nice. Hope we can rescue it on mac.
I hope too and I think you outlined solution below is the way to go :-)
I think the choice is easy to make for developers.
Hum not so clear... what do you recommend? Either we disable the
cache on Mac or we make it a preference settings for those preferring
the speed over the look...
Does it sound reasonable to check for overlaps of the text pixmaps, to
put the background color into the pixmap signature and to use
non-transparent bitmaps instead?
Seems the obvious way to go.
In math mode I get some graphic errors by that method,
I guess you have to care of left and right bearing of first and last
character or symbols. Not an easy stuff (I've been through all this
while implementing this stuff) but it's doable.
but in text everything looks fine (all by just using my pure white
background everywhere).
Good!
How big is the speed gain anyway of the whole approach?
On Windows the speed gain is noticeable but not exceptional because text
drawing is quite fast to begin with. I had a report sometime ago from a
user with an old PPC Mac that the speed gain was very nice.
Abdel.
