__________
CHAPTER
3
PROGRAMMING
PROGRAMMING
BIT
IMAGE
GRAPHICS
You
can
also
write
a program that prints a graphics image directly,
without
transferring it from the display screen. This section explains
how
to
do
this using BASIC statements.
Your printer prints graphics images in successive columns
of
eight
dots. The LPRINT statement that tells the printer to do this
has
three
components:
• The control code sequence that puts the printer into graphics
mode,
• The number
of
columns to be printed, and
• The coded data that tells the printer
which
dots to
print
in each
column.
First,
we
discuss each part separately, then put them together.
There are
four
modes
of
bit
image graphics available
with
the
IBM-compatible
MICROLINE. They
differ
in horizontal resolution,
or
density. This indicates
how
close together
the
dots are;
it
is
measured by the
number
of
dots
per
inch. All modes have a
vertical resolution
of
72
DPI. For reference,
the
diameter
of
a
dot
is
1/72 inch. The modes are discussed in
more
detail in
the
next
section
on
control codes.
The maximum
width
of
a graphics image
is
8 inches for the
ML
182.
1 . Control Codes
A graphics LPRINT statement begins with a control code that tells
the printer to print a graphics image.
Each
graphics mode
has
a dif-
ferent control code.
61
To Next Page
Loading...
