[reportlab-users] sizes of fonts and images

Tim Roberts timr at probo.com
Tue Oct 24 13:01:46 EDT 2006

Luc Saffre wrote:

>On 23.10.2006 23:40, Andy Robinson wrote:
>>If you are using Courier 10 point, the characters are actually 6 points
>>wide.  All courier glyphs are 600 ems wide.  10 is the 'height',
>>including whatever whitespace the designer wanted at the top.
>This was indeed the missing piece in my jigsaw. The size of a font is
>the height of its bounding box! And the font metric values in a TTFont
>instance (bbox, ascent, descent, defaultWidth...) are expressed in
>1/1000 of this size.

Not always, unfortunately.  Those units are referred to as the
"em-square", and the unit of measure for the em-square is up to the font
designer.  Postscript fonts usually use 1000x1000.  Some TrueType fonts
use 1000x1000.  Some use 2048x2048.  I've seen references to fonts with
em-squares of 15000x15000, although I've never encountered one.

Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.

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