HP PCL 5 - Page 98

2-50 Printer-Specific Differences ENWW
In the MS-Mincho and MS-Gothic fonts provided in the
HP LaserJet 4PJ, font metric calculation is somewhat easier than for
the Latin-based fonts. Width calculations are easier because all
characters of these fonts conform to one of two different character
widths at a particular point size. The characters are either considered
full-width or half- width. One-byte characters are always half-width
and two-byte characters are always full-width.
Full-width characters occupy the entire EM width at a particular point
size. Half-width characters occupy half of an EM width. The following
equations show how to calculate the EM width and character widths
for a full-width and a half-width character.
ppem = round (DeviceResolution * PointSize/72)
FullWidthDeltaX = round (ppem * PCLUnits/ DeviceResolution)
HalfWidthDeltaX=round ((ppem/2) * PCLUnits/DeviceResolution)
where:
ppem = EM width in pixels
DeviceResolution = current device resolution in dots per inch
(600 or 300dpi)
PointSize = point size requested
FullWidthDeltaX = character width of full-width character in PCL Units
HalfWidthDeltaX = character width of half-width character in PCL Units
PCLUnits = PCL Units
The PCL Unit of measure is explained in more detail in the PCL 5
Technical Reference Manual. The default PCL Unit size is 1/300th of
an inch, but the Unit of Measure command can be used to set the
PCL Unit size to other values.
Note that HalfWidthDeltaX may not be exactly half of FullWidthDeltaX
because of rounding. For example, if FullWidthDeltaX = round(99.0) =
99, then the corresponding HalfWidthDeltaX = round(99.0/2) =
round(49.5) = 50.