Category : Assembly Language Source Code
Archive   : DOCFILES.ZIP
Filename : DRAW.DOC

 
Output of file : DRAW.DOC contained in archive : DOCFILES.ZIP
DRAW Michael J. Mefford
Command 1987/No. 9

______________________________________________________

Purpose: Provides low-resolution (320 x 200) color or
high-resolution (640 x 200) monochrome
drawing capabilities on a color, enhanced
color, or (with some MGA boards) a monochrome
display, without the need to work in BASIC.

Format: [d:][path]DRAW[/K] (Option I)
[d:][path]DRAW string[/K] (Option I)
[d:][path]DRAW filespec/F[/K] (Option II)

Remarks: Entered at the DOS prompt with no arguments
on the command line (Option I), DRAW looks in
the current directory for a file named
DRAW.DAT and executes the commands in that
file. A sample DRAW.DAT file is included on
this disk. The file can be examined, and
similar files created, with a regular ASCII
word processor.

Alternatively, DRAW can be entered with a
string of commands (Option II, for a simple
graphic) or with the name of a file
consisting of commands (Option III). Any
legal DOS filename may be used, and full path
support is provided, but a /F terminator must
be appended to the filename. An optional /K
may be added to prevent a keystroke from
halting execution.

Example: You can get a feel for how DRAW operates by
entering, at the DOS prompt:

DRAW X0 C2 BU50 M+40,70 L80 M+40,-70 BD5 P2,2

This will create a red triangle in the middle
of your screen. You can trace the specific
steps in this command sequence by referring
to The DRAW Command Set table, presented on
succeeding pages in this manual.

The DRAW Command Set

Xn Change to low resolution 320X200 color graphics.

If X is not found, the default is 640X200 high
resolution black and white graphics. X must be
the first character of the command line or the
first character in a file.

The palette will be changed to n, where n can be
either zero or one. See C color command below for
the color of each palette.

K Do not poll the keyboard while drawing. If K is
not found, any keystroke terminates the program.

Sn Flood the screen color to pattern n. n must be a
decimal number in the range 0-255, and represents
an eight bit pattern. Normally this command is
issued immediately after the X command (if
present), to clear the screen with a background
color other than black. For example, to clear to
color red (2) in low resolution, the command is
S170 (binary 10101010).

color 320X200 640X200
0 0 0
1 85 255
2 170 NA
3 255 NA

Pattern colors may also be used. For example, a
pattern of half green and half black would be S58
(binary 01000100). In high resolution, each bit
represents a dot, eight dots per byte. This is
why only two colors (black or white) are
available. In low resolution, there are two bits
per dot, so four combinations can be represented.
In the example here the sequence is 01 (green), 00
(black), 01 (green), 00 (black). See C (color)
command below for complete coding of the colors.

U,D,L,R,E,F,G,H
These commands, followed by a number, will move in
one of the following compass directions:

U
H | E
\ | /
\ | /
\ | /
L -- -- -- + -- -- -- R
/ | \
/ | \
/ | \
G | F
D

Mx,y Move x,y units either relative to the current
position or to the absolute coordinates, x,y. If
the x coordinate is prefaced with either a plus
sign or minus sign, the move is relative.
Otherwise, the move is absolute. Note, you do not
need to include a plus sign in front of the y
coordinate in a positive y move.

Pp,b Paint the color p until the border color b is
found. The paint originates from the current
position.

B Blank move. The move following a B will move the
desired units without plotting points. The next
command will then continue drawing.

N No update. The draw command following an N
command will plot points, but the position will
not be updated. The next draw command will start
at the same position as the last.

Cn Change the color to n. All draws after a C
command will be in color n. n can be 0 (black) or
1 (white) in high resolution and 0 to 3 in low
resolution. In low resolution, the color is
dependent on the palette.

320X200 640X200
color palette 0 palette 1
0 black black black
1 green cyan white
2 red magenta NA
3 yellow white NA

RELATED COMMANDS

Four commands, BSAVE.COM, BLOAD.COM,
LOWRES.COM, and HIGHRES.COM, are included on
this disk to speed the display of pictures
created by DRAW. (BSAVE and BLOAD may also
be used with text screens for instant
presentation.) The command

BSAVE filespec

saves a byte image of the screen buffer to a
file (with optional drive and path
specifications), and

BLOAD filespec

writes the saved image back to the screen
buffer.

LOWRES and HIGHRES are used in batch files
with BLOAD to set the appropriate display
resolution.

Example: Create the following batch file, SAVE.BAT,
using an ASCII word processor, EDLIN, or COPY
CON:

ECHO OFF
DRAW DRAW.DAT/F
BSAVE PICTURE

Now, similarly create a second batch file,
INSTANT.BAT:

ECHO OFF
LOWRES
BLOAD PICTURE
PLAY STING.DAT/F
PAUSE > NUL
MODE CO80

If you now enter INSTANT at the DOS prompt
the picture of two con men will appear, with
appropriate musical background. Pressing any
keystroke will clear the display.

Note:

1. The PAUSE > NUL line in INSTANT.BAT
prevents the DOS prompt from intruding
on the picture, but will not work on DOS
versions prior to DOS 3.


  3 Responses to “Category : Assembly Language Source Code
Archive   : DOCFILES.ZIP
Filename : DRAW.DOC

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