PEN color
The PEN
command define the color that will be used to draw lines, shapes, or write text
on the screen. In practice, it is like choosing the color of a pen or marker before you
start drawing. Depending on the hardware capabilities of the computer, the range of colors
available could be limited or very large. Some systems used predefined color palettes,
while others allowed you to define your own colors.
In order to be isomorphic, the color
parameter repesents a value in the available
color shades. For this very specific reasons, each color is encoded by a literal constant,
like WHITE
or YELLOW
. Those constants will be replaced by proper color index or
values, depending on the hardware. Obviously, you can directly put the numeric value
for the color, but you have to know the underlying encoding of the colors.
So the graphics capabilities of the PEN
command are closely tied to the capabilities of
the target running the program. The resolution of the screen affected the quality of the colors displayed.
On lower-resolution screens, colors could appear less sharp. Some systems offers a wider color
gamut and more flexibility in defining colors. Others use a limited color palette could result
in some uniformity in the colors available. In some target you can define your own palettes,
so there is no guarantee that the constants and values are the same.
You can use the DEFAULT
constant to use the default pen color for
the considered target, again if no color replacement has been done.
PEN 4 PEN esempio
Pn
If you have encountered a problem using this command, if you think there is a bug or the explanation is unclear, please open an issue for this keyword on GitHub. Thank you!