Problems with linearHoriAdvance

[Thomas Hudson]

I am trying to calculate escapements for each glyph
as a floating point value that when multiplied by
the point size will return the width in pixels.

It seems that linearHoriAdvance is not correct:

(gdb) p *mFace->glyph
$2 = {library = 0x8601e10, face = 0x86aa4e8, next = 0x0, flags = 0,
generic = {data = 0x0, finalizer = 0}, metrics = {width = 0, height = 0, 
horiBearingX = 0, horiBearingY = 0, horiAdvance = 180, vertBearingX = 0, 
vertBearingY = 0, vertAdvance = 2379}, linearHoriAdvance = 481,
linearVertAdvance = 2379, advance = {x = 180, y = 0}, 

The docs say that this value should be in 16.16 format, but the 
value of 481 above doesn't seem meaningful in this context.

I did notice the line in ahhint.c:
ahhint.c:      /* XXX: TO DO - slot->linearHoriAdvance */

Is there something missing here or am I doing something wrong?

Thanks,
Thomas