[cairo] Screen orientation

[Jean-Claude Repetto]

Hello,

I am using Cairo in a handheld device with a LCD screen. The device has 
a frame buffer, so I am using Cairo image surfaces to draw directly into 
the frame buffer.
Unfortunately, some of the devices have been manufactured with a LCD 
screen rotated of 90 degrees. I have tried to use a Cairo transformation 
matrix. It works, but it is much slower.
Is there a possibility of avoiding the cost of a matrix multiplication ? 
Changing the orientation requires only a swap between X and Y, and/or a 
substraction.

Naturally, I could write two versions of the application, but I'd prefer 
avoid this solution. A solution with two versions of the Cairo library 
is acceptable.

Thanks for your suggestions,
Jean-Claude