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Updated July 3 2003

Font Selection using Characteristics


Here is a basic introduction to font selection using the characteristics of the font.

Notes:
    Bitmap font - fixed bit-pattern for each character, size is fixed.   Scalable font - outline of the characters, easily scaled to produce range of sizes. *1
    Internal font - resident on printer ROM or downloaded.   Soft font - resides in RAM

There are two methods used to select fonts.  With the first, soft fonts can be specified using their associated ID numbers – <Esc>(#X for primary fonts, and <Esc>)#X for secondary fonts, where # is the soft font ID.  I will be adding this information as soon as time permits.

The second method is to use the Font Select Table.  There are two independent font select tables: primary font (SI) and secondary font (SO) table.  These tables store the values of the characteristics of their current fonts.  The default settings come from the control panel settings.  We can change the values in these tables by sending PCL commands.  After changes are made the machine performs a “Font Select”.

Font Select
A Font Select searches available fonts and scalable typefaces to select the one that most closely matches the characteristics in the font select table.  It is an elimination process with 9 (10) steps.  Start with all the fonts.  Check the first characteristic and remove all fonts that do not have this characteristic.  Move to the next characteristic with the remaining fonts and only keep the fonts that have this characteristic.  And the beat goes on till these is only one font is left.  This could be while still in the middle of the table or right at the very end.

Resolution is a step, but not really counted.  That is why I have the (10) above.  At 300dpi, 600dpi bitmap fonts are eliminated before the selection begins.  At 600dpi, the priority is 600dpi bitmap, scalable, 300dpi bitmap fonts.


Considerations from highest priority
1. Symbol set
2. Spacing
3. Pitch
4. Height
5. Style
6. Stroke Weight
7. Typeface Family
8. Location
9. Orientation


All command examples are based on the primary font table
.
Symbol set   <ESC>(ID, where ID is the symbol set
Identifies the specific collection of symbols provided by a font.

Spacing
  <ESC>(s#P, where # is 0 for fixed and 1 for proportional  *2
Fixed-spaced and proportionally-spaced.  In fixed-spaced the inter-character spacing is equal whereas in proportional-spaced fonts the inter-character spacing varies with the shape of the character.

Pitch
  <ESC>(s#H, where # is the number of characters per inch
Number of characters per inch (for fixed-spaced fonts only) common ones are 10, 12, 16.67.  Used to calculate height for fixed-spaced scalable fonts.

Height
  <ESC>(s#V, where # is the number of points
Ignored for fixed-spaced scalable fonts.  Measured in points, it is the height for the body of the type or "Em" *3
For bitmap and TrueType fonts there are 72 points in an inch.  For intellifonts there are 72.307 point in an inch.

Style
  <ESC>(s#S, where # is the number corresponding to the style type.(1 is italic)
Posture (upright or italic)
Width (condensed, normal, expanded, …)
Structure (solid, outline, shadow, …)

Stroke weight
  <ESC>(s#B, where # is the number corresponding to the weight. (3 is bold)
Thickness of the stroke.  Light, standard, bold, …     standard is also called medium.

Typeface Family
  <ESC>(s#T, where # is the number corresponding to the typeface. (16602 is Arial)
Comic Sans, Arial, line printer, …   the character design.

Location

For older printers with SIMM Fonts and Cartridge fonts
Soft font have priority over internal fonts

Orientation
 *4
For bitmap fonts – if more than one font still exists at this point, the orientation of the font is considered.
Landscape, reverse landscape, portrait, reverse portrait


The commands and their values for changing all these features can be found in the HP PCL Comparison Guide.

Following the example on a previous page... Lets say we want to used a fixed spaced font at 12 CPI, what would we need to do?
The escape sequence for Fixed-spaced fonts is <ESC>(s0P and we already know the escape sequence for 12 CPI is <ESC>(s12H

<ESC>E<ESC>(s0P<ESC>(s12HHello World<ESC>E

Notice that the parameterized character and the group character are the same(they both deal with font selection).  There is a process in place to write out commands with the same parameterized character and group character in a short form.  Notice the terminating character in the middle of the escape sequence is now lower case, no longer terminating the sequence just its own value.  Anyway the above would become:

<ESC>E<ESC>(s0p12HHello World<ESC>E

You can see that this could save lots of time if you where entering 5 commands for font selection instead to the 2 we just did.  Here is a real world example.


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*1.  Scalable font - grouping of outline characters limited to one specific symbol set.
    Scalable typeface - grouping of outline characters of a specific typeface which can produce multple symbol sets.

*2.  Character size by spacing.  Fixed space bitmap font - both pitch and hieght are used to select the character size.   Fixed space scalable fonts - only pitch is used.  Proportional spaced fonts - only hieght is used

*3.  Em - Body of the type - slightly larger than the distance from the bottom of a descender (section below the base line) to the top of an unaccented capital letter.

*4.  Orientation - Newer printers can automatically rotate fonts to the current orientation making all fonts available in all four orientations.  Eariler printers required the font to be in the orientation of the page.  Therefore, orientation is not as important as it once was.