FORMS LAYOUT CONSIDERATIONS
Rounding measurements
Laser printing systems use only dot units in the actual
performance of forms compilation. Therefore, as long as all
positioning commands within FDL are defined in terms of dots or
an integral number of dots, there are no rounding problems.
Converting other unit values to dots
You may define positions in decimal-valued inches, in
centimeters, in lines per inch, and in characters per inch. The LPS
converts all of these commands to dots while the form is being
compiled.
Many of the possible values defined (lines per inch, centimeters,
and so forth) cannot be reduced to an integral number of dots.
For example, if a coordinate system uses 13.6 characters per inch
(cpi), that number may be translated to approximately 22.058823
dots per character unit. The compiler rounds the converted
number to the nearest whole dot before starting to compile the
form.
Example
The example statements below illustrate the problems
encountered using the 13.6 cpi coordinate system.
AT 4 DRAW 1 HOR LINE FROM –1 TO 132 USING SOLID 1;
AT 5 DRAW 1 HOR LINE FROM –1 TO 132 USING SOLID
HAIRLINE;
AT 8 DRAW 15 VER LINES FROM 4 TO 5 USING HAIRLINE AND
REPEAT HOR EVERY 8;
In theory, this form description technique creates 14 boxes that
can be found simply by addressing the appropriate coordinates.
In fact, the coordinates of the boxes are not exactly those
expected. The boxes can be found by using the IN NEXT BOX
parameter of the TEXT IN BOX command.
The IN NEXT BOX parameter works properly because it specifies
the next adjacent box but does not specify the coordinates of
that box. The problem in addressing coordinates is that the FDL
statement requires vertical lines every 176.47058 dots, which is
rounded down by the system to 176.00000 dots.
This difference makes it impossible for the LPS to find box 14 at
the coordinates 4, 112. There are two ways to draw the form to
overcome this problem. One way is to draw 13 lines with the
REPEAT parameter and then specify lines at 112 and 120.
Another way is to change the final statement in this manner:
AT 8 DRAW VER LINE FROM 4 TO 5 USING HAIRLINE AND AT
16, 24, 32, 42, 48, 56, 72, 80, 88, 96, 104, 112, 120;
Unless a form is described with a coordinate system of only dots
or an integral number of dots, the REPEAT parameter cannot be
used to draw boxes that must be referenced by their
coordinates.
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XEROX 4850/4890 HIGHLIGHT COLOR LPS FORMS CREATION REFERENCE
