[cairo] Semantics of transparent objects on opaque targets (image
cworth at cworth.org
Fri Jan 13 12:34:30 PST 2006
On Fri, 13 Jan 2006 15:16:22 -0500, Michael Sweet wrote:
> I agree that this is the right thing to do - basically, if you don't
> draw a background then you'll get an implementation/surface-defined
> default background, which for PostScript output is white.
Thanks for the confirmation of the concept.
Note that even if you "draw a background" the default background can
still be made visible, (such as the black that appears when using
CLEAR with an RGB24 target surface).
> On a separate, nit-picky note, your PS output does not conform to
> the Adobe Document Structuring Conventions:
Hey, thanks for the careful look. This is greatly appreciated!
> 1. No Pages: comment in the header (you need at least a
> "%%Pages: (atend)" in the header)
This one is a recent regression which I committed in the past few
days, (the output had "%%Pages: N" previously), and I've been planning
to put that back soon.
But the recommendation of "(atend)" is even better. That means I can
fix this much sooner.
> 2. The header comments indicate ASCII (Clean7Bit) data, but
> you are embedding binary data.
> 3. There is no %%EndPage comment defined by the DSC.
Thanks for these corrections. I'll fix those.
> 4. Presumably you'll want a %%Pages comment after the
Yes, easy to do.
> 5. Unless you are really using Level 3 language elements,
> the %%LanguageLevel comment should specify version 2.
> (this one is not really a DSC problem, but a general nit)
The comment we have in cairo for this one is:
/* The "/FlateDecode filter" currently used is a feature of
* LanguageLevel 3 */
I'll have to look closer to see if that's still appropriate.
> Once I have finished up CUPS 1.2 (probably sometime in March), I'll
> be happy to work with you on this part of Cairo...
We'll definitely look forward to your contributions!
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