PRB: Average & Maximum Char Widths Different for TT Fixed Font (92410)
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) 3.1
- Microsoft Win32 Application Programming Interface (API)
This article was previously published under Q92410
3.10 4.00 | 3.50 3.51
WINDOWS | WINDOWS NT
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SYMPTOMS
The tmAveCharWidth and tmMaxCharWidth fields of the TEXTMETRIC structure are not equal for a fixed-pitch TrueType (TT) font such as Courier New.
RESOLUTION
This is by TrueType design. The tmMaxCharWidth denotes the maximum
possible ink width of the font rather than maximum cell width of
the font.
STATUS
This behavior is by design.
MORE INFORMATION
TrueType fonts use ABC character spacing. The "A" width is the
distance that is added to the current position before placing the
TrueType glyph. The "B" width is the width of the black part (ink
width) of the TT glyph. The "C" width is the distance from the end of
the "B" width to the beginning of the next character. Advanced width
(cell width) is equal to A+B+C.
The physical TT fonts that are passed to drivers have just the "B"
part of the characters, so all fonts at the level of the driver appear
to be proportional width fonts. The tmMaxCharWidth is the least width in which the "B" part of all characters will fit. The tmAveCharWidth is the average advance width (A+B+C). For a fixed-pitch TT font such as Courier New, the A+B+C width is the same for all characters; however, the maximum width as defined above can be different.
tmMaxCharWidth is greater than tmAveCharWidth only if A+C is negative. This is possible for a fixed-pitch font.
Please see section 18.2.4.1 of the Windows 3.1 SDK "Guide to
Programming" for more information about ABC character spacing.
| Modification Type: | Minor | Last Reviewed: | 2/11/2005 |
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| Keywords: | kbprb KB92410 |
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