[cairo] Help in X-Scaling

Maarten Bosmans mkbosmans at gmail.com
Tue May 25 03:01:13 PDT 2010

2010/5/25 Mj Mendoza IV <mjmendoza at konsolscript.org>:
> My understanding of "x scale" is different to how cairo implemented it in
> cairo_scale.
> Here's how I thought it would work.
> I have a 50x50 (WxH) surface, x scaling it twice should give me 100x50
> (WxH), cairo_scale did so as expected. Upon rotating 90degrees (1.5707963...
> radians), I expected for the image to keep the 100pixel-wide crosswise
> scaling while rotated in 90degrees. But, as it rotated 90degrees, the image
> started to stretched lengthwise instead.
> (Don't know if I'm making any sense here. I think I should make an
> illustration instead)
> Anyway, to others who had the same problem, may I ask how you managed to
> maintain the 100x50 (WxH) as it rotates.

I'm not sure I completely understand what you mean. In any case an
important pointer here can be that it matters in which order you apply
the matrix operations. So first scaling then rotating gives a
different result than vice versa.

> Regards.
> Mj Mendoza IV,
> Developer, KonsolScript
> http://www.konsolscript.org


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