[cairo] change orientation landscape portrait

[Lawrence D'Oliveiro]

On Mon, 13 Jul 2015 13:33:34 +0200, Alex Vazquez wrote:

> I want to know if it is posible change orientation landscape to
> portrait in Cairo.

See also the get_image_from_png routine here
<https://github.com/ldo/render-useful/blob/master/render-batch>.