Re: Why do all these methods of measuring string metrics with font attribute fail?
Re: Why do all these methods of measuring string metrics with font attribute fail?
- Subject: Re: Why do all these methods of measuring string metrics with font attribute fail?
- From: Graham Cox <email@hidden>
- Date: Fri, 5 Sep 2008 00:05:57 +1000
On 4 Sep 2008, at 11:27 pm, an0 wrote:
If they give no useful information for
application programmers,
Yes they do, but perhaps just not for your application. If you want to
use glyphs as a graphic element for example, it's sometimes useful to
query these sizes without having to try laying them out as text.
Remember, there is a big difference, conceptually, between a string (a
collection of characters) and a font (a collection of glyphs). Glyphs
are graphical entities, and most of the stuff in NSFont and
NSFontManager is there to support these concepts at that level.
Your problem (and confusion) appears to stem from the fact that you
seem to think that a font is something like a string, and so can be
treated as a collection of characters. The layout of glyphs to form an
image of a string of text on the screen is a complex process, and
applications that do this need to know all sorts of metrics beyond
"how much space does this string occupy". In fact to calculate that
they need to add up the space occupied by each glyph, and some of the
methods you mentioned are there to support that sort of processing.
cheers, Graham
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