Re: Pango crossplatform layout size query

On 9/04/2010, at 4:49 AM, Behdad Esfahbod wrote:

On 04/06/2010 08:09 PM, Richard Procter wrote:
However, the cairo documentation states "hinting font metrics means
quantizing them so that they are integer values in devicbehdad behdad orge space". This
suggests I'm wrong and that layout remains device dependent.

??  If you *disable* hinting font metrics, you are supposed to get
device-independent layout.

Right, that's what I thought.

"quantizing ... so that they are integer values in device space" though
suggests otherwise to me; I will go bug the cairo guys.

I have tested this using the attached C program on OS X 10.4,
Debian Linux (lenny), and Win32, using the same MS arial.ttf font file.
OS X and Linux get identical logical extents, but win32 differs (see
below for details - in fact it doesn't appear to honour the option).

IIRC neither win32 nor quartz cairo font backends respect the hinting flags
(yet).  That's a bug.

It looks like quartz has been fixed - it matches linux with metrics
hinting off and differs with it on.

I will raise a bug for the win32 backend if there isn't one already.

If I understand metrics hinting, this last is a bug, and I can rely
on the others to remain equal, plus or minus a pixel? If so, can
I expect this to hold for other scripts?

Yes.  The script is not relevant.

Great. I take it that I am basically on the right track then and that
when you said cross-platform results without metrics hinting were
'fairly robust' you were thinking of that single device pixel.

many thanks,

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