[Webkit-unassigned] [Bug 18694] [CAIRO] Problem with rotation in a given matrix in SVG

[bugzilla-daemon at webkit.org]

http://bugs.webkit.org/show_bug.cgi?id=18694





------- Comment #2 from vbs85 at gmx.de  2008-04-24 12:53 PDT -------
The values are given correctly to AffineTransform (in SVG-specification):
like matrix(a,b,c,d,tx,ty)
If you transform an SVG-object with Cairo, b and c are interchanged. That
means:
matrix(a,c,b,d,tx,ty) is the same on cairo like the matrix above on SVG. Thats
why the interchange of c and b in AffineTransform should be correct. But the
SVG-object is displayed wrong with it.

I searched in GraphicsContestCairo and found the method
void GraphicsContext::concatCTM(const AffineTransform& transform)
In this method "transform" is changed back to a cairo_matrix_t with
reinterpret_cast. 

I asked in IRC and it COULD be that this transformation interchange b and c in
the background while transforming "transform" to cairo_matrix_t.
Perhaps, thats why cairo_matrix_init(&m_transform, a, c, b, d, tx, ty); doesn't
work correctly.

So you should use a other possibility to change the type to cairo_matrix_t or
you use cairo_matrix_init(&m_transform, a, b, c, d, tx, ty);


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