[news.eclipse.platform.swt] How to calculate character widths?

[Stefan Matthias Aust <sma@xxxxxxxxx>]

I'd like to determine the true width of single characters.

I try to find a way to create a packed bitmap with all characters to use 
that as a texture for OpenGL.  However, I've trouble to measure the font.

There's GC#getCharWidth() but on Windows, this method only returns the 
"B" width of a character.  As documented, this is the width without 
leading or trailing whitespace or overhang.  However, some fonts have 
such an overhang.  Let's assume an uppercase A which has some 
tail-thingy as shown below:

     /\
    /__\
   /    \_ uto _
          -__-
 ^ ^            ^
 '-'------------'
  A    B ^------^
            -C

This character has a small "A" leading, a large "B" width that includes 
the "tail" and a negative "C" which tells the renderer where to start 
the next character - "u" in my example.

How do I get the other two values besides B?  ...without directly 
calling the OS.GetCharABCWidths() method?  Is there a platform 
independent way to get the width "A" or "C"?  Can I safely assume that 
GC#getAdvanceWidth() will always return A+B+C?


Interestingly, getAdvanceWidth() uses OS.GetCharWidth().  MSDN however 
says, that this method cannot be used for truetype fonts.  Why does this 
work then?


bye
--
Stefan Matthias Aust   //
www.3plus4software.de // Inter Deum Et Diabolum Semper Musica Est