Use cairo instead of librsvg to render antialiased png's (from svg)

[Tiziano Müller]

At the moment librsvg is needed to render antialiased png. The problem is that the dependencies for this lib in fact require a complete X-Window environment.
With cairo and libsvg-cairo (and the python-bindings of course) it would be possible to render the svg's generated by the graphviz tools to png with very decent performance.

Example-Code:

import cairo, cairo.svg
svgctx = cairo.svg.Context()
svgctx.parse("test.svg")
width, height = svgctx.get_size()
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
ctx = cairo.Context(surface)
svgctx.render(ctx)
surface.write_to_png("test.png")

I'll try to write a patch within the next week.

[Radek Bartoň]

Futhermore there is an unpleasant bug in dot's SVG export where long labels overlaps node, which makes this file type unusuable to draw UML class diagram charts.

[whiteblizzard]

Workaround for this is to specify:

#!graphviz.dot/gif

as the header for your dot code. This way you loose the anti-aliasing, since it isn't implemented for gif files. Caveat: If you set a size parameter the fonts will look very ugly.

[anonymous]

stair parts Frequent Buyer Discounts available to Builders & Contractors on stair parts and wrought iron balusters We Ship Fast - Call us for an estimated shipping time. ​iron railing and fences with decor design We offer both Amish Quality and Contractor Grade Stair Parts. ​step railing Our customers are loyal, find out why!

[Christian Boos]

Suggesting a wontfix here, as graphviz itself can be built with cairo support, see ​http://www.graphviz.org/Download_source.php.

Looking at version 2.20.3 (current stable as of today), it's even the default:

  --with-pangocairo=yes   pangocairo library

Installing all the dependencies is of course a bit tedious if you have an old system, but probably no more work than getting the dependencies for the suggested pipeline (or the one suggested in #1610). Once you have it in place, it's certainly a more robust solution.

[Christian Boos]

Replying to cboos:

Suggesting a wontfix here, as graphviz itself can be built with cairo support, see ​http://www.graphviz.org/Download_source.php.