Loadstar 231/231.d81/t.dbasic intro

Text File | 2003-01-01 | 7.3 KB | 313 lines

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           D O T B A S I C
           by Dave Moorman


    Creating applications with all the
pazzazz and sparkle of mouse control
just got easier -- with DOTBASIC. This
is an extension to BASIC 2.0 that
includes Mr.Mouse 2.1, Visual Design,
Object Oriented Programming, and an
Event Driven environment.

    These are concepts being used in
PC programming languages such as
Visual Basic.

  VISUAL. The programmer "draws" the
screen (rather than writing a bunch of
PRINT statements), using

  OBJECTS. A button has length, width,
color, caption, and more. These are
attributes to the Button Object. The
programmer sets the attributes
(visually) and doesn't have to worry
about it again. OBJECTS also have one
or more

  EVENT attributes. When the user
clicks the button, the Event Handling
subroutine (written by the programmer)
is called, making the button do
whatever the button does.

    DOTBASIC brings these to our
modest world, making coding quick and
painless. (OK -- we're going hyper-
bolic here!) But imagine you have a
utility in mind, one with several
functions to be presented on the main
screen. Here are the three steps to
making a DOTBASIC program.


           DRAW IT VISUALLY

    LOAD and RUN "B.VDOT", the visual
design program. Here you can type,
draw blocks of text, edit the font,
and paint colors. (Check the [Control]
menu for the various options.) Design
your screen the way you want it to
appear.

    Now create Event Regions on your
screen. Press <F1> (to make the menu
bar appear) and click [Edit] > [Box].
Move the square pointer to the upper
left corner of the area you want the
user to click for some particular
function. For example, you probably
have a "QUIT" button. Once the square
in is place, click, then move the
mouse down and right to open up the
brackets to enclose the area you want
for an Event Region. Click again.

    The Edit menu will reopen. Click
[Add Region]. You are presented with a
suggested Line Number. Press <Return>.
For Right Click Enable, press <N>. For
Hotkey, choose an appropriate letter
key and input it.

    Now input the Unhighlighted color
(probably the color you are using for
the button), and press <Y> if you want
it reversed. Do the likewise (with
different colors or reversal) for the
Highlighted color. Finally, Press
<Y> if everything is the way you want
it.

    Repeat the process for each Event
Region you want. (Or later you can run
VDOT, load your file, and add Regions
at will.) When done, click [File] >
[Save] and choose the [MED] file
option.

    Type in the filename you want for
this program. All working files will
use the same name (with different
prefixes and extensions). Click OK.
Then click [File] > [Exit].


             BUILD A BOOT

    Step two is to create your program
template. This is extremely easy.
LOAD"B.DOT",dv and list line 60008.
Change the line to include your
program name (the one you used for
your MED file -- without the .MED).

    60008 N$="MYPROG"

Then type

    GOTO60000<RETURN>

to save your new boot file. Once it is
saved, RUN it.

    The boot program will look for
"MYPROG.DOT" -- and if it is not
present, will create it for you. (You
will see some text flash on the screen
as this happens, but don't worry! It
only happens once.) The title screen
will appear.

    The DOT program will then attempt
to attach the Event Regions you
designed and assigned to the
subroutine line number(s). Since they
are not present yet, the line numbers
and default commands are displayed on
the screen, followed by an UNDEF'D
LINE NUMBER  ERROR.

    Move the cursor up to the
displayed line numbers and press
<RETURN> on each. Type

          GOTO60000<RETURN>

 Then RUN the program again.

    Your designed screen will appear,
along with the mouse arrow. Use the
mouse, cursor keys, or joystick to
move the arrow. When it is over an
Event Region, the color will change to
the Highlighted color you selected.
You can cycle through hightlighted
Event Regions by pressing the <UP
ARROW>.

    However, at this point, clicking
on the Event Region will not do
anything -- because you have not
written the Event Handling
Subroutines.


           WRITING THE CODE

    Press <BACK ARROW> to Escape the
program, and LIST it. You will see:

 90 SYS5120
 100 .DO:.EE:.WA:.UN E%:.OF
 101 END

    Welcome to DOTBASIC! You have up
to 72 new commands at your disposal,
several of which are right here.

 .DO starts the DO-loop.

 .EE Enables the Event Sensor.

 .WA Watches for a <BACK ARROW>
     keypress.

 .UN E% loops back to the .DO until E%
     is not 0.

 .OF turns off DOTBASIC and puts BASIC
     2.0 back where it was when
     SYS5120 was called.

    Now you may be wondering how the
program gets to the subroutines! It
all happens behind the scenes, making
this an Event Driven program
environment.

    Let's do the EXIT routine,
assuming the Event Region is attached
to line 1000.

 1000 REM"       EXIT
 1005 .RU, 218, 215
 1010 E% = I%
 1015 .ER
 1020 RETURN

    Enter these lines and RUN the
program. You should see an "Are You
Sure?" box with an active Yes/No
control.


           [IMPORTANT NOTE]

    If you have an ERROR, type

             .OF<RETURN>

 before trying to edit the code. This
turns off everything so no problems
will occur.

    Here are the meanings of the
commands:

 .RU,u,h turns on the Are You Sure box
   and waits for the Yes or No to be
   clicked. Yes: I% = -1. No: I% = 0.
   U is the unhighlighted color. H is
   the Highlighted color. Add 208 to
   the color code of both the get the
   selected item unreversed.

 E% = I% puts the result of .RU
   (in I%) into E%. Remember, when E%
   is not 0, the .UN command in the
   main loop falls through.

 .ER Event screen Restore. When an
   Event occurs, the screen is stashed
   at page 232. This command brings it
   back.

 RETURN takes DOTBASIC back to the
   main loop. The Event Sensor is
   turned off during Event Handling,
   which is why .EE (Event Enable) is
   in the main loop.


    After you have writen the code for
each attached Event, your program is
finished! And remember, you have 77
commands to do marvelous things with
your program!

    When copying your program to a
separate disk, copy the following
files (MYPROG = Your Program Name):

    B.MYPROG
    MYPROG.MED
    MYPROG.DOT
    MOUSE2.1 7K 2400
    DF.ML

    You can use Lee Novak's LINKER and
PACKER to put everything together in a
single program file. For the BASIC
file, choose MYPROG.DOT. Add Modules
-- MYPROG.MED, MOUSE2.1 7K 2400, and
DF.ML. You will have to change the
load address of MYPROG.MED to 57344
(Page 224). You will no longer need
B.MYPROG to boot your program.


SOME TECHNICAL INFORMATION

    DOTBASIC uses several variable
names to pass information from the ML
routines to BASIC:

    I% - The all-purpose Integer.

    E% - The Enable flag, used in the
      main loop, which will continue
      as long as E% = 0.

    FP - The Floating Point variable
      for returning values too large
      for I%.

    DOTBASIC uses only one area above
page 64:

 Pages 224-242 is where your MED file
is loaded and the main screen is
stashed during Event Handling
routines.

    And don't forget to type

             .OF<RETURN>

 after every BASIC ERROR.


    Be sure to read the DOTBASIC
Command List for descriptions of each
command. Next month, we will include
Lee Novak's masterful Mr.Mouse2.1
documentation -- updated with DOTBASIC
commands.

 DMM