Light thru Windows
Volume Number: 1
Issue Number: 4
Column Tag: Basic school
Light thru the Windows
By Dave Kelly
Let’s put some light on the subject of windows. Almost everything you write in
Microsoft BASIC 2.0 requires some window programming. This is e specially true if
you want your program to conform to the Macintosh user interface. First, a rundown
on the commands we have available to program our windows:
WINDOW window-id [title ]
[,[rectangle ][, type ]]]
WINDOW CLOSE window-id
WINDOW OUTPUT window-id
WINDOW OUTPUT #file-number
The window-id identifies the output window. Window-id is a number from 1 to
4. This means that you may only have up to 4 windows open at any one time. BASIC
opens up Window 1 when BASIC starts. If this window gets closed you can select the
output window from the Windows menu in BASIC or type WINDOW 1 from the command
window. A window must be open and specified as the output window before anything can
be printed in the window.
The title is the name displayed in the title bar of a document window if the
window has a title bar.
The rectangle specifies the location of the window on the Macintosh screen. It is
given in the form (x1,y1)-(x2,y2) where (x1,y1) is the upper left corner of the
window and (x2,y2) is the lower right corner of the window. This sounds easy but
someone out there will probably be confused. The entire Macintosh screen has a
resolution of 512 X 342. To open a window which fills the entire screen you could use
(0,0)-(512,342). However, you’ll find that the desktop border (for pull down
menus will cover the title bar of your document window. The desktop border on the top
of the screen is about 40 pixels down from the top. By using (2,40) as the top corner
and (510,340) as the bottom corner your window will fill the screen except for the
desktop border. A couple of pixels are allowed at the edge of the screen to make it look a
little better. So much for filling the entire screen with a window. It can require some
trial and error to get your window positioned where you want when you try to center a
smaller window on the screen. Other BASIC commands use the rectangle format to
specify the location relative to the upper-left corner of the window. The rectangle
format in the WINDOW command specifies the location of the window relative to the
upper-left corner of the screen.
There are 4 types of windows that are available with type. They are (for type
=1-4) :
1. Document window
2. Dialog box with two line border
3. Window with simple one-line border
4. Window with a shadow
Only type 1, the document window, has a size box and a title bar. Also, only type
1 can be moved with the mouse. The other types will not change position on the screen
without redefining the window with the WINDOW command. A negative type number is
called a modal dialog box. In this case any attempt to select outside of the window
results in a beep.
The WINDOW CLOSE statement closes the indicated window. WINDOW OUTPUT
indicates which window will be the window used for output when there are multiple
windows. This allows you to send output to another window without changing the active
window. If a file-number is indicated instead of a window-id, the output will be sent
to the indicated file. Currently, only files opened to LPT1: are valid with this
statement. As other devices which support graphics are made available, this will
change.
Info About Windows
The window function WINDOW(n) returns information about the windows. If n =
0, the function returns the window-id of the active output window. n = 1 returns the
window-id of the current output window. This is the window where output will be
sent. n = 2 gives the width of the current output window and n = 3 returns the height
of the current output window. n = 4 and n = 5 returns the x and y coordinate
(respectively) in the current output window where the next character will be drawn.
This function may be used to determine where the next character or section of a
drawing should continue.
Our sample window shows how these commands are used to control windows. The
program sets up all four windows as type 1 (document with size box and title).
Information about each window is printed in the window. The information about the
width and height might be used when trying to get just the right sized window for your
program.
An important thing to note when working with windows is that everything does
not happen automatically as you may be used to when moving, opening, or closing
windows in application programs you may have run. You have to do everything which
you took for granted before. For some people this may be hard to figure out, but just
try to imitate the way the commercial applications are supposed to use the Macintosh
user interface. Try this with my sample program: move one of the windows on top of
another and then back again. The printed information which may have been destroyed
by overlaying a window over another needs to be refreshed. Changing the size box has
the same effect.
REFRESHING WINDOWS
The DIALOG(5) function returns the window-id of the window which needs to be
refreshed. Updating a window is not automatically performed but must be done by the
program. In the Event: subroutine when DIALOG(0) sets d=5, the output window is set
to the window indicated by DIALOG(5) and the window is printed again. It would be
desirable to setup a subroutine to refresh windows if this feature is desired. Just for
fun, delete the line that starts with IF d=5 THEN WINDOW OUTPUT DIALOG(5) and
then run the program. You can see that the window will not be automatically refreshed
without this event trapping. In some programs you may not want to refresh all (or
even any) of the windows.
The print windowinfo: subroutine prints the information on the current output
window. You can change this and print your own message if you like. Try changing the
window type just to see what it will do.
The command LOCATE[row][,column] positions the pen at a specified row and
column in the output window. This position is with respect to the upper-left corner of
the current output window. Since most fonts are proportionally spaced, the spacing is
that of the letter “0”, because it is an average width for most fonts. Another way to
control the location of the pen is the use of CALL GETPEN, CALL MOVETO(x,y) or CALL
MOVE(xdelta,ydelta). (Note: MSBASIC 2.0 allows you to optionally leave off the word
CALL and just use the routine name-useful for creating your own basic commands by
calling machine language routines).
Notice that by selecting the active window from the pull down menu causes a
different result than clicking on the window. When the window is clicked it is selected
as both the active and output window. By selecting from the menus, one window can be
active while output is going to another. This is exactly the same procedure used when
refreshing the screen. This is observed by changing the output window from the menu.
To return to BASIC, use the quit menu.
You now have an introduction to windows. The important thing to remember is
that you must control where windows are opened, and which windows are selected or
deselected, and which window is the output window. For simple programs which only
need a place to print, the statement WINDOW creates an output window if none
currently exsists and makes it active. Your program will have to do the work of
deciding what should be done with each window, as it is not automatic. Do you have
some questions or programming tips to share with MacTutor’s reader’s? Send your
questions or contributions to BASIC SCHOOL care of MacTutor, P.O. Box 846,
Placentia, CA. 92670.
‘ Window Demo
‘ by Dave Kelly
‘ MACTUTOR March 1985
‘SET UP MENUS
MENU 4,0,1,”Quit”
MENU 4,1,1,”Return to BASIC”
MENU 5,0,1,”Output Window”
MENU 5,1,1,”Window 1
MENU 5,2,0, “-” ‘MENU DASH LINE
MENU 5,3,1,”Window 2
MENU 5,4,0, “-”
MENU 5,5,1,”Window 3
MENU 5,6,0, “-”
MENU 5,7,1,”Window 4
MENU 6,0,1,”Active Window”
MENU 6,1,1,”Window 1
MENU 6,2,0, “-”
MENU 6,3,1,”Window 2
MENU 6,4,0, “-”
MENU 6,5,1,”Window 3
MENU 6,6,0, “-”
MENU 6,7,1,”Window 4
‘TURN ON MENU SELECT TRAP
ON MENU GOSUB menus:MENU ON
‘SET UP WINDOWS and PRINT INFO
WINDOW 1,”Window 1",(2,40)-(252,190)
GOSUB print windowinfo
WINDOW 2,”Window 2",
(260,40)-(510,190)
GOSUB print windowinfo
WINDOW 3,”Window 3",
(2,195)-(252,345)
GOSUB print windowinfo
WINDOW 4,”Window 4",
(260,195)-(510,345)
GOSUB print windowinfo
DIALOG ON
‘ENABLE EVENT TRAP
ON DIALOG GOSUB Event
pause:GOTO pause
Event:
d=DIALOG(0) ‘EVENT OCCURED
‘d=3 USER CLICKED INACTIVE WINDOW
IF d=3 THEN window.picked=
DIALOG(3):WINDOW window.picked
‘d=4 USER CLICKED GO-AWAY BOX
IF d=4 THEN window.closed=
DIALOG(4):WINDOW CLOSE
window.closed
‘d=5 WINDOW NEEDS TO BE REFRESHED
IF d=5 THEN WINDOW OUTPUT
DIALOG(5):GOSUB print windowinfo
RETURN
menus:
‘THIS HANDLES MENUS
menunumber=MENU(0)
menuitem=MENU(1):MENU
IF menunumber<>4 THEN menu5
‘MENU 4 QUITS
MENU RESET:END
menu5:IF menunumber<>5 THEN menu6 ‘MENU 5 SELECTS OUTPUT WINDOW
IF menuitem=1 THEN WINDOW OUTPUT 1
IF menuitem=3 THEN WINDOW OUTPUT 2
IF menuitem=5 THEN WINDOW OUTPUT 3
IF menuitem=7 THEN WINDOW OUTPUT 4
GOSUB print windowinfo
RETURN
menu6:
IF menunumber<>6 THEN RETURN ‘MENU 6 SELECTS ACTIVE WINDOW
menuitem=MENU(1):MENU
IF menuitem=1 THEN WINDOW 1
IF menuitem=3 THEN WINDOW 2
IF menuitem=5 THEN WINDOW 3
IF menuitem=7 THEN WINDOW 4
GOSUB print windowinfo
RETURN
print windowinfo:
LOCATE 1,1
PRINT”Current active window is “;
WINDOW(0)
PRINT”Current output window is “;
WINDOW(1)
PRINT”Window width is “;WINDOW(2)
PRINT”Window height is “;WINDOW(3)
RETURN