GWBASIC User's Manual

GW-BASIC User's Guide
LINE Statement
Purpose:
To draw lines and boxes on the screen.
Syntax:
LINE [(x1,y1)]-(x2,y2) [,[attribute][,B[F]][,style]]
Comments:
x1,y1 and x2,y2 specify the end points of a line.
Resolution mode is determined by the SCREEN statement.
attribute specifies color or intensity of the displayed pixel (see the COLOR and PALETTE
statements).
B (box) draws a box with the points (x1,y1) and (x2,y2) at opposite corners.
BF (filled box) draws a box (as ,B) and fills in the interior with points.
Note
If attribute is not specified, two commas must be used before B or BF.
LINE supports the additional argument style. style is a 16-bit integer mask used when putting
down pixels on the screen. This is called line-styling.
Each time LINE stores a point on the screen, it uses the current circulating bit in style. If that bit
is 0, no store will be done. If the bit is a 1, then a normal store is done. After each point, the next
bit position in style is selected.
Since a 0 bit in style does not clear out the old contents, you may wish to draw a background
line before a styled line, in order to force a known background.
style is used for normal lines and boxes, but is illegal for filled boxes.
If the BF parameter is used with the style parameter, a "Syntax" error will occur.
When out-of-range values are given in the LINE statement, the coordinates that are out of range
are not visible on the screen. This is called line-clipping.
In the syntax shown here, the coordinate form STEP (x offset, y offset) is not shown.
However, this form can be used wherever a coordinate is used.
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