ITherm® 280 Unicode and Fonts iTherm
®
280 Programmer’s Guide
Page 258 Rev C 28-07764
Stroke-based characters
With stroke based characters, the points stored are along the center line. Less
than half the points are needed to render stroke based characters. This
improves character-generation performance and uses less space.
This type of character generation is fast and efficient, and is ideally suited for
Asian fonts.
Character Definition
True Type and Stroke fonts are designed as a complete font with character cell size and
character position in the cell based on the overall font design. Typical the characters are
defined as vectors and stored as coordinates on a character cell grid. The grid is in an arbitrary
design unit and may be up to 4096 units on a side.
In most systems character sizes is specified as a point size where the point size refers to the
character height. The character width is typically variable and designed to produce the optimal
appearance. The font rendering system must take the requested point size and generate a
character based on the original design units and produce a character that is the correct size and
position for the printer.
In most font designs, the vertical point size includes white space between lines. The font
designer defines the height of the character cell in design units for all characters then defines a
character origin that will be used for all the characters in the font. The designer then defines
individual character sizes based on how the font is supposed to look and all the characters that
are to be included. Characters are then positioned in the cell based on this origin. All
characters in the font are then based on the same rules. The white space between lines in
defined to be above the character.
The information available at print time is listed above. The complete cell is not provided, only
the escapement, black width and depth and the x and y offsets to the origin are available. The
printer cannot arbitrarily shorten the cell height that was defined by the font designer even
though the provided character may fit in a smaller space. Using these rules, may result in
characters that at first appear too small with excessive white space between lines, however this
is how the font was designed. The printer must allow the minimum line spacing based on the
