On Jun 10, 2007, at 09:31 AM, Ingemar Ragnemalm wrote:
Transparency, anti-aliasing: Not really an issue, QuickDraw does them
pretty well.
Quickdraw only really understands binary transparency (regions). It
only anti-aliases text (and not as well as Quartz). Quartz natively
understands full alpha transparency and can anti-alias everything.
Well, that is one of my arguments: Contrary to what is often claimed,
QuickDraw natively
understands full alpha transparency (although not in the RGBA grouping)
and can antialias
everything with very little extra effort. Wrap your drawing routine with
a supersampling
ditherCopy, and wrap drawing with transparency with calls that CopyMask
your drawing
properly. No problem, no low-level pixel processing, not much extra
code, it is all in
standard QuickDraw.
But the biggest advantage of Quartz is that you can take the same
drawing commands you use to draw to screen, and virtually unmodified
use them to create a PDF or Print, or to create an image of any DPI.
Absolutely. The resolution independence, splines, floating-point data
etc, are very important.
That's where QD has flaws that can't be worked around. I have seen
picture collections that
would have been so great if the shapes were not all integer-based
polygons, and instead the
shapes are not good enough to print, especially if zoomed.
My conclusion is of course that CG is more modern (no question about
it), but it is
also fun to break some illusions of QD's inabilities while pointing
out the REAL
strengths.
Quickdraw had a forward looking design for it's day. It's the only
reason why it was viable as a primary graphics system for over 15
years. But if you feel that Quickdraw really does have a strength
somewhere that is overlooked in Quartz (and I won't say that isn't
possible) then filing a feature enhancement would be highly
appreciated :).
I am not in any way trying to point backwards, not saying that QD should
be of much use
today, other than possibly making QD-CG glue to ease porting, but it
somewhat fun to
show that some popular CG "strengths" are mostly void, they were already
there, while
noting what REALLY counts. And there are things to learn by expanding
the list.
If this discussion can surface some omissions in CG, or not well-known
workarounds, the better.
On more thing: QD Bottlenecks. (Could have been a subject of its own.)
The QD bottlenecks is a very powerful technique that I still wish to see
a replacement for, and
I am surprised that I find very little discussions on the topic
(googling and searching Apple docs).
"The GrafProcs bottleneck tricks simply don’t apply in Quartz." says the
docs
(QuickDrawToQuartz2D), as if it was suddenly irrelevant to process the
contents of metadata.
There are tons of tricks to play with the bottlenecks. Sure it will be
very different with CG, the
drawing commands are different, but the usefulness can hardly be gone.
As an example, I have often used PICTs for storing polygonal paths, for
example for animation
paths. They should really have been splines, but I can always do a
Catmull-Rom along the
polygon and get a nice result. But how do I do the same in CG? How can I
take a standard
document from a drawing program (e.g. Illustrator) and extract a path
from it? Parse a PS file?
I want something that is stable, simple and fast, because that's what I
had before.
/Ingemar
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