[cairo] Screen orientation

[Koen Kooi]

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Carl Worth schreef:
> On Mon, 10 Dec 2007 22:38:28 +0100, Jean-Claude Repetto wrote:
>> I am using :
>> 	cairo_rotate (cr, M_PI/2);
>> 	cairo_translate (cr, 0, -screen_width);
> 
> So that looks just fine.
> 
> And the question, like Behdad said, becomes "what exactly is slow in
> this case?".

I don't know how cairo rotates things, but when we experienced slowness
running X in the correct user rotation, Richard Purdie patched kdrive,
illustrated with the following comment:

- - * Copy the bits, always write across the physical frame buffer
- - * to take advantage of write combining.
+ * Copy in blocks of size BLOCKSIZE_WIDTH x BLOCKSIZE_HEIGHT
+ * to reduce the number of cache misses when rotating 90 or
+ * 270 degrees.

So the slowness could be due to cache-misses, but as I said, I don't
know how cairo rotates things.

regards,

Koen

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