Re: Problem: how to get glyph descent and ascent
Re: Problem: how to get glyph descent and ascent
- Subject: Re: Problem: how to get glyph descent and ascent
- From: Graham Cox <email@hidden>
- Date: Wed, 24 Jun 2009 11:08:30 +1000
On 24/06/2009, at 4:02 AM, Anders Lassen wrote:
The font descent is the maximum descent for all characters in that
font, so it will not help me to position the character correct.
In general, I don't think it's meaningful to ask for the metrics
ascender, descender, and so on for an individual glyph. Those metrics
apply to a font as a whole. A glyph is just a path that sits inside a
bounding box, and certain positions on that path (such as the height
of the top of the curved part for the letter 'd' for example) are not
recorded. What is noted is the positions of some layout guidelines
such as the xHeight, baseline and overall ascender and descender.
However, most rational fonts do stick to the guidelines, so these
metrics are useful for positioning glyphs. If you do need finer
metrics for the mathematical formula layout task, you may need to
choose a couple of fonts and build some supplementary tables yourself
for handling the positioning.
This page (and the guide it is part of) are must-reads: http://developer.apple.com/documentation/Cocoa/Conceptual/FontHandling/Tasks/GettingFontMetrics.html
--Graham
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