Light thru Windows
|Column Tag:||Basic school
Light thru the Windows
By Dave Kelly
Lets put some light on the subject of windows. Almost everything you write in Microsoft BASIC 2.0 requires some window programming. This is especially 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, youll 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.
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 printwindowinfo: 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 MacTutors readers? Send your questions or contributions to BASIC SCHOOL care of MacTutor, P.O. Box 846, Placentia, CA. 92670.
by Dave Kelly
MACTUTOR March 1985
SET UP MENUS
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)
WINDOW 2,Window 2",
WINDOW 3,Window 3",
WINDOW 4,Window 4",
ENABLE EVENT TRAP
ON DIALOG GOSUB Event
d=DIALOG(0) EVENT OCCURED
d=3 USER CLICKED INACTIVE WINDOW
IF d=3 THEN window.picked=
d=4 USER CLICKED GO-AWAY BOX
IF d=4 THEN window.closed=
d=5 WINDOW NEEDS TO BE REFRESHED
IF d=5 THEN WINDOW OUTPUT
THIS HANDLES MENUS
IF menunumber<>4 THEN menu5
MENU 4 QUITS
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
IF menunumber<>6 THEN RETURN MENU 6 SELECTS ACTIVE WINDOW
IF menuitem=1 THEN WINDOW 1
IF menuitem=3 THEN WINDOW 2
IF menuitem=5 THEN WINDOW 3
IF menuitem=7 THEN WINDOW 4
PRINTCurrent active window is ;
PRINTCurrent output window is ;
PRINTWindow width is ;WINDOW(2)
PRINTWindow height is ;WINDOW(3)