www.delorie.com/gnu/docs/hp2xx/hp2xxinf_6.html

search

	Buy GNU books!

HP2XX, A HP-GL Converter

2.2 Sizing your output

NOTE: The basic unit length within hp2xx is mm (millimeter). This unit is always assumed except where noted otherwise.

In contrast to a real HP-GL plotter, hp2xx lets you decide freely about the size of the picture. While preserving the picture's aspect ratio, hp2xx will fit the picture into a window of width w and height h. By default, w = h = 200 (mm). Set these basic sizes using options `-w w' and `-h h'.

Sometimes you'll want to change the aspect factor of a picture, e.g., to spread out a square picture into landscape. Option `-a af' is used for this. af > 1 increases x/y ratio, 0 < af < 1 decreases x/y.

Example: Let's assume your picture covers a native coordinate range of 100...900 plotter units in x direction and 200...600 in y direction. Thus, its width is double its height. Using defaults, hp2xx will create a picture of size 200 x 100 mm, while options `-w 100 -h 40' will lead to a picture of size 80 x 40 mm, and `-w 100 -h 40 -a 0.5' results in a 40 x 40 mm picture.

Alternatively, ignore explicit size control and rely on the true HP-GL coordinates (and therefore: sizes) of the given input file(s). Flag `-t' inhibits `-a -h -w' and lets hp2xx use true HP-GL sizes, based on the assumption that 1 HP unit = 1/40 mm.

Some modes of hp2xx support page offsets, i.e., left and upper margins added to the picture, probably in addition to some hard margins which cannot be avoided. Currently, these modes are eps, pcl, and pre. The left margin (offset) is modified with option `-o off_left', while the upper margin can be controlled via `-O off_upper'. off_left and off_upper are specified in mm.

Option `-C' (center the picture) works in combination with options `-o -O' by modifying the offsets in such a way that the resulting picture is centered within the frame defined by options `-w -h'. Example: Assume that the picture is a square, and `-w 100 -h 40' are specified. A 40 mm square with an additional left margin of (100-40)/2 = 30 mm will be produced if option `-C' is given. If the actual width/height ration of the picture exactly matches the ratio defined by `-w -h', option `-C' has no effect.