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Q44206: Explanation of the _fontinfo Structure

Article: Q44206
Product(s): See article
Version(s): 2.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 18-MAY-1989

Question:

Which entries in the _fontinfo structure pertain to which fonts?
Specifically, do 'ascent' and 'pixheight' pertain to vector fonts?
Those two fields do not seem to change after the size of a vector font
is changed.

Response:

All entries in the _fontinfo pertain to both font types. The two known
values that are specific to each type are as follows:

   *.type      =>  If bit is set = vector font, clear = bitmap font
   *.pixwidth  =>  0 = proportional, others = character width in pixels

For bitmapped fonts, the sizes are known; therefore, each font size is
stored separately.

For vector-mapped fonts, there is only one known size; therefore, only
one size is stored in the font file. When you select a vector font
with a specific size, the font routine will rescale the desired size
proportionally to the known size. This is why all entries in _fontinfo
structure are UNCHANGED (including the 'ascent' and 'pixheight'
fields) every time the size of a vector-mapped font is changed.

For example, setting the vector-mapped font size to either of the
following will not have any effect on the _fontinfo values:

      'h100w200'
or
      'h10w20'

This means that the size of a vector-mapped font will be changed
correctly, but you will not be able to tell to what size it was
changed to by looking at the _fontinfo structure fields.

This is currently a limitation of QuickC 2.00.

Note: For an explanation of differences between 'ascent' and
'pixheight,' please refer to Pages 654-655 in the book "Programming
Windows" by Charles Petzold.

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