HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part II

17-24 An Introduction to HP-GL/2 Vector Graphics EN
Scaling
When you scale a drawing, you define your own units of measure-
ment instead of using plotter units; the printer converts your units
(user-units) to dot positions for placing the image on the page.
Scaling allows control of the printer using units that are easy for
you to work with.
For example, you can scale your drawing to divide the drawing area
into 100 squares. As you plan the drawing, you can think in terms
of 100 squares rather than plotter units. Here is another example of
scaling: since 400 plotter units equals 1 centimeter, you can establish
this scale to print in user-units equal to 1 centimeter each.
Scaling begins with the scaling points, P1 and P2. P1 and P2 act as
two points marking opposite corners of a rectangle. You can make
this rectangle any size and place it anywhere in relation to the origin,
depending on the plotter unit coordinates you specify for P1 and P2.
(P1 and P2 default to the lower left and upper right corners of the
picture frame, respectively, but you can change their locations using
the Input P1 and P2 (IP) or Input Relative P1 and P2 (IR) commands.)
After you have defined the positions for P1 and P2, or have accepted
the default, use this imaginary rectangle to set up scaling for your
drawing. With the Scale (SC) command you specify how many
sections the rectangle divides into horizontally (the X-axis) and how
many sections the rectangle divides into vertically (the Y-axis). With
this process you have created your user-units.
Scaling also allows you to enlarge or reduce your image by changing
the locations of P1 and P2. P1 and P2 represent physical locations
in relation to the PCL Picture Frame. When the imaginary rectangle
formed by P1 and P2 is enlarged or reduced with the IP or IR
commands, the HP-GL/2 image is also enlarged or reduced to fit the
new P1/P2 rectangle. (For a more detailed explanation of scaling
and the Scale (SC) command, see Chapter 19.)
For importing existing HP-GL/2 images, another method of enlarging
or reducing drawings exists. It involves varying the size of the PCL
Picture Frame and is described next. This method allows you to scale
an image while maintaining the aspect ratio of all elements (including
fonts). The Scale command does not affect the size of fonts.