[cairo] _cairo_surface_wrapper_get_target_extents() too small

Simon Sapin simon.sapin at exyr.org
Wed Mar 27 05:12:36 PDT 2013


When rendering to PDF with WeasyPrint a document containing a SVG image, 
SVG elements in the right and bottom of the image are not shown in some 

git bisect indicates that the bug appeared in this cairo commit:


Reverting it on top of today’s master fixes the bug.

WeasyPrint has CairoSVG render the image to an intermediate cairo SVG 
surface, which is then used in surface pattern as a source to paint in 
the final PDF surface. The bug appears when the target context has a 
scale to make the image smaller than its "intrinsic" size. Making the 
SVG surface smaller (with its content scaled accordingly) and 
compensating with a scale on the target surface works around the problem.

Apparently, the rectangle returned by 
_cairo_surface_wrapper_get_target_extents() is smaller than it should 
be. Something is transformed wrong, but I’m not sure what coordinate 
system each rectangle is supposed to be in.

Simon Sapin

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