jiho wrote:
On 2007-October-31 , at 22:10 , Carl Worth wrote:
On Sat, 20 Oct 2007 11:53:07 +0200, jiho wrote:
On 2007-October-18 , at 00:09 , Carl Worth wrote: I noticed that there is no cairo 1.5.2 at this address. Are you still planning to make a git snapshot?
Sorry about the delay. The 1.5.2 snapshot is here now:
http://cairographics.org/snapshots/cairo-1.5.2.tar.gz
And I'm definitely interested in hearing reports from inkscape users about cairo's PDF output with this snapshot. It should be lots better than cairo 1.4.10. But if you can find any regressions, I *definitely* want to hear about those.
Some notes on what's new in 1.5.2 compared to 1.4.10 can be seen here:
I (eventually) installed this new Cairo into my MacPorts install, compiled with the pdf backend enabled (--enable-pdf) and tested Inkscape's output on a simple test file of mine. The results are mixed:
- transparency is supported in Adobe Reader but not in Preview (OS X
image viewer): the object is simply not displayed. Actually Preview is just a front end to Cocoa's PDFKit which is what all OS X applications dealing with PDFs use. So at this point, Cairo's output is clearly not usable yet. Inkscape's old pdf exporter with transparency looked OK
I don't have a Mac so can't check this myself however one of the cairo Mac developers, Brian Ewins, had a look and confirmed that the PDF displays correctly in Preview on Leopard but fails to display correctly on Tiger. I am assuming you are using Tiger.
The transparency in the PDF created by the old exporter is created by setting the alpha in the graphics state (/ca and /CA) before filling and stroking the path. The result is that the stroke color is blended with the fill color where they overlap. When zooming in on the stroke it can be seen that the stroke is split into two colors.
The transparency in the cairo PDF exporter is created by drawing the fill and stroke in a group using opaque colors then calling cairo_paint_with_alpha() to draw the group with a constant alpha over the entire group. This results in a uniform stroke color that matches what is seen on screen in Inkscape. In the PDF cairo_paint_with_alpha() is implemented by setting a SMask with a uniform alpha in the graphics state then drawing the group. However it appears that the Tiger version of Preview does not correctly implement SMasks.
You can obtain the old behavior with the cairo pdf exporter by filling and stroking the path with a transparent color instead of using cairo_paint_with_alpha() however this is not going to match the screen display.
- blur is not supported (this is not surprising however). the object
is not even rasterized, it is just displayed without the blur
The cairo API does not support blur so Inkscape will need to draw a rasterized image. Even if cairo did support blur, PDF does not, so either way this needs to be rasterized to obtain correct output.
all gradients are well supported
bitmaps embedded or linked are conserved
markers and clones are handled perfectly
So the largest issue, by far, is the transparency. Many applications on OS X deal with PDFs and they all use PDFKit. Plus, Preview is a very slick and fast PDF viewer so I guess that most people go with it and don't even install the huge, over-crowed and slow adobe reader. It can't be considered as an alternative then. I am conscious that, since Adobe Reader renders Cairo's PDF correctly, the bug is probably on Apple's side. But I am afraid there is no way they would change this soon and the effort will have to be done on Cairo's side. I hope it will not be too hard to fix.
This appears to have been fixed in Leopard. There is no work around that can be implemented in cairo for PDF viewers that do not support SMask other than image fallbacks.
As a last note it seems like if Cairo's PDF ouput, though of reasonable size, made both Preview and Adobe Reader choke on the file, to the point of hanging several seconds, when zooming far in (>1000%). Other PDF files on my machine do not lead to this kind of behaviour.
Brian tells me that he can not reproduce the slow down in Leopard.
Anyway, it really feels like there was progress but just the last few bits were missing. I hope they will be solved by Inkscape release time. It would be extraordinary to have kick-ass PDF support, both at import and export, for this release. Thanks for your effort.
PS: pdf-test-case in svg and pdf at this address http://jo.irisson.free.fr/dropbox/inkscape/
JiHO
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