[cairo] Cairo usage - multiple formats + SVG

Stephan Siemen Stephan.Siemen at ecmwf.int
Tue May 20 00:00:22 PDT 2008


we at ECMWF (www.ecmwf.int) have developed a (free) library to
read and visualise meteorological data/statistics. This library
is called Magics++ and is documented at


We support various graphics output formats and now consider to
use Cairo as a way of achieving PostScript, PDF, SVG and PNG output.
We have implemented a "output driver" using Cairo and our first
impression is that Cairo is very good.

We have however some points we would like to have more information
if possible:

- Currently we run our "CairoDriver" for each format requested
 separately. Would it be possible to use one surface description
 to generate multiple outputs? We have users who would like to
 generate PDF and PNG at the same time. This would mean a big
 improvement for us.

- Perhaps related to the previous point, would it be possible that
 all outputs have the some convention of definition? Currently defining
 PNG output is different from PDF output.

- We are very happy with the PNG output, but are there any plans
 to have a more generic raster based output which could be used to
 generate (animated) GIFs or APNG? Any plans to support Flash?

- The SVG output we currently generate (without Cairo), has
 no 'width' and 'height' attributes for the overall <svg> tag.
 This makes the resulting graphics scalable in the sense that
 the size adjusts to the size of the display area (at least that is
 how it works in Firefox). Could there be a option to
 generate SVG output without the size being fixed?

- Are there any plans to add support for scripting in SVG
 output? This has not to be through directly adding code
 but adding 'groups' tags and 'id' attributes could help
 already. We would like to toggle layers of displayed data
 on/off or make them transparent if possible.

- Last but not least, is there a "Cairographics inside" logo? :-)

Sorry, if I ask questions which have been answered previously,
but we are new to Cairo and still have to learn a bit. :-)


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