Basic computer language commands

Basic computer programming language

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.

In a LINE statement, if the relative form is used on the second coordinate, it is relative to the first coordinate.

After a LINE statement, the last referenced point is x2, y2.

The simplest form of LINE is the following:

LINE -(xz,yz)

This draws a line from the last point referenced to the point (x2,y2) in the foreground color.

Examples:

LINE (0,100)-(639,100)

Draws a horizontal line which divides the screen in half from top to bottom in SCREEN 2.

LINE (160,0)-(160,199)

Draws a vertical line which divides the screen in half from left to right in SCREEN 1; makes a one-quarter/three-quarter division in SCREEN 2.

LINE (0,0)-(319,199)

Draws a diagonal line from the top left to lower right corner of the screen in SCREEN 1, and from the upper left corner to the center bottom of the screen in SCREEN 2.

LINE (10,10)-(20,20),2

Draws a line in color 2 if SCREEN 1 is previously specified (see the COLOR statement).

10 CLS
20 LINE -(RND*319,RND*199),RND*4
30 GOTO 20

Draw lines forever using random attributes.

10 FOR X=0 TO 319
20 LINE (X,0)-(X,199),X AND 1
30 NEXT

Draws an alternating pattern: line on, line off.

10 CLS
20 LINE -(RND*639,RND*199),RND*2,BF
30 GOTO 20

Draws lines all over the screen.

LINE (0,0)-(100,175),,B

Draws a square box in the upper left corner of the screen.

LINE (0,0)-(100,175),,BF

Draws the same box and fills it in.

LINE (0,0)-(100,175),2,BF

Draws the same filled box in magenta in SCREEN 1.

LINE (0,0)-(100,350),,B

Draws the same box if SCREEN 2 is specified.

400 SCREEN 1
410 LINE(160,100)-(160,199),,,&HCCCC

Draws a vertical dotted line down the center of the screen in SCREEN 1.

220 SCREEN 2
230 LINE(300,100)-(400,50),,B,&HAAAA

Draws a rectangle with a dotted line in SCREEN 2.

LINE (0,0)-(160,100),3,,&HFF00

Draws a dotted line from the upper left corner to the screen center.

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