[cl-pdf-devel] transparency?

[Marc Battyani]

"Cyrus Harmon" <ch-lisp at bobobeach.com> wrote:
>
> On May 24, 2007, at 2:39 PM, Marc Battyani wrote:
>
>> "Cyrus Harmon" <ch-lisp at bobobeach.com> wrote:
>>
>>> Is there a way that I can set the page background to be  transparent 
>>> using cl-pdf? I'd like to be able to draw (at least  partially) opaque 
>>> items onto a transparent background but can't  figure out how to do so.
>>
>> What do you mean by transparency? Alpha channels? The text drawing  for 
>> instance has no background color so is already transparent  except for 
>> the glyphs.
>
> What I want in this case is solid text on a transparent background.  I'll 
> keep digging.

I don't understand what you mean. Text is already solid on a transparent 
background. The page is white if you don't put something on it but it's not 
the text that paints it white.

>> IIRC, the PNG also supports transparency for the images.
>
> hmm... the png reading code says:
>
>  (otherwise (error "Alpha channel not supported ~s" pathname))
>
> so it would appear that pngs with alpha channels aren't supported,  BICBW.

No alpha channels, but tranparency is there. There is even an example in 
png-example.lisp

Marc