[vwnc] Cairo question...

Hi all -- not sure who to direct this at -- I've got a question
regarding the method below that Cairo adds to the Pixmap class :

cairoSurface
    ^CairoGraphics.Surface concreteDisplayClass pixmap: self

Does this mean that I can draw a pixmap with whatever I want and then
call the above method and somehow tell
Cairo to generate a PDF from the pixmap contents?    Just thought I'd
ask.. Thx!
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On May 29, 2009, at 11:45 PM, Rick Flower wrote:

> Hi all -- not sure who to direct this at -- I've got a question
> regarding the method below that Cairo adds to the Pixmap class :

I might be able to help you. :)

> cairoSurface
>    ^CairoGraphics.Surface concreteDisplayClass pixmap: self
>
> Does this mean that I can draw a pixmap with whatever I want and then
> call the above method and somehow tell
> Cairo to generate a PDF from the pixmap contents?    Just thought I'd
> ask.. Thx!

Not exactly, at least as far as I understand your question.

PDFSurface and a HostSurface (QuartSurface, XLibSurface, Win32Surface)  
are two distinct kinds of surfaces that Cairo can render to. There is  
no "take any surface and make a PDF file out of it." I've not had luck  
drawing to a Pixmap surface, and then using that as a source for a  
PDFSurface. But I have been able to do it with an ImageSurface:

surface := ImageSurface format: CairoFormat argb32 extent: 100@100.
surface newCairoContextWhile: [:cr |
                cr
                        source: ColorValue red;
                        paint].
pdf := PDFSurface path: '/Users/travis/Desktop/torick.pdf'
                        pointExtent: 72 @ 72.
pdf newCairoContextWhile: [:cr |
                cr
                        source: surface;
                        paint;
                        showPage].
pdf finish

I haven't had the time to figure out why a Pixmap derived surface is  
not happy there. I don't know if it's OSX specific problem, or cross  
platform. To get around the Pixmap problem, I might do something like  
this (which I tested):

p := Pixmap extent: 100 @ 100.
(p graphicsContext)
        paint: ColorValue blue;
        displayRectangle: (20 @ 20 corner: 80 @ 80).
image := p asImage.
image becomeCairoCompatible.
pdf := PDFSurface path: '/Users/travis/Desktop/torick.pdf'
                        pointExtent: 72 @ 72.
pdf newCairoContextWhile: [:cr |
                image newCairoSurfaceWhile: [:surface |
                                cr
                                        source: surface;
                                        paint;
                                        showPage]].
pdf finish

--
Travis Griggs
Objologist
My Other Machine runs OSX. But then... so does this one.



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Travis Griggs wrote: Thanks Travis.. I'll play around with it some more.. One thing I should
point out is that IF
I were to use a pixmap and happened to render some text to it and later
generate a PDF,
I'd not want to have the text be a bitmap...  I think I'll need to look
at some of the other
surfaces...  I'm trying to make this play with Simberon and have been in
contact w/ Chris
Lopeman on that end -- I'm just trying to still put some of the puzzle
pieces together still..
Thanks!

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