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HP2XX, A HP-GL Converter

2.3 Pen sizes and colors

Imagine a plotter with a pen carousel, e.g., like the model HP7550A. The carousel carries a (small) number of pens. Their colors and tip thicknesses (sizes) are selected by a human operator, while the plotter only receives commands like "Now use pen number 5". If you don't provide a pen, the plotter will move and "draw" without this pen if its number is selected.

hp2xx emulates a carousel of up to 8 pens of various colors and sizes. By default, all pens are present, have foreground color (typically black), and their tip thicknesses are one unit (1/10 mm). (NOTE: in versions before 3.4.2, pen widths in raster modes were counted in pixels, so the default in those versions was 1/10 mm for vector modes, 1 pixel for raster modes).

HPGL/2 commands NP,PC,PW may override this for up to 255 freely configurable pens.

Pen colors and sizes are represented by digits to allow for a compact option list. There are 8 colors including background (usually white). See section B. Option summary, the Option Summary, for a list of all colors. E.g., color 3 is green, and color 7 means yellow. Permitted pen sizes are 0 ... 9 units in versions before 3.4.3, or up to 3.5mm (using characters A to Z to denote the range from 1.0 to 3.5) in later versions. NOTE: In versions of hp2xx before 3.4.3, all raster mode pen sizes were approximated by double, triple, etc. width, and lines wider than 4 would normally not give useful results. In 3.4.3, the line drawing algorithm has been substantially improved and should render accurately scaled pen widths.

Options `-c c-string' and `-s s-string' tell hp2xx about the pens to be placed in the carousel. c-string and s-string are strings of 1 to 8 digits, corresponding to special choices of pen 1 to 8. Defaults are c-string = s-string = `11111111' unless the hpgl file contains corresponding PC and/or PW commands. Specifying `-c' or `-s' overrides the equivalent HPGL/2 command. If you specify less than 8 pens, the remaining pens keep their defaults.

Examples:

hp2xx -p13 foo.hp

Show a preview of `foo.hp', drawing all lines with pen #2 three pixels wide instead of default 1 pixel, which applies to all other pens.

hp2xx -c12740 -p12230412 foo.hp

Here, pen #5 is "removed". Pens #1 and #7 keep their default sizes, all others are set to various sizes. Pen #2 is red, #3 is yellow, and #4 is blue, while all other pens keep `foreground' color, e.g., black.

If your HP-GL file contains the PC and/or PW commands introduced with HP-GL/2, these are interpreted to allow up to 255 pens. The special case where a pen is redefined to take on different colors is currently only supported in PostScript or PDF output mode. In all other modes, the last PC command encountered determines that pens' color for the entire plot.