"A Fat Bits Approach to Cursor Editing"

By Dave Kelly, Hybrids Engineer, MacTutor Editorial Board

Let's take a look at one of the Macintosh ROM routines which can be called from MSBASIC (version 2.0). By using the method described here, you can customize your own cursors for use within your programs.

Pages 298 and 299 of the MS BASIC manual explain the Mouse Cursor Handling Routines. The program 'Cursor Editor' in this article demonstrates how to build your own cursor using the CALL SETCURSOR (VARPTR( cursor %(0))) function. It would be helpful to enter the program and run it as you read the explanation here.

Fig. 1 Cursor Edit Program Menu

When you run the program, the main BASIC menus are replaced by a new File and Cursor menu. The Cursor menu allows you to edit the current custom cursor. The Arrow is the default cursor and cannot be edited unless you duplicate it as a custom cursor of your own. Choosing 'Hand' sets the cursor to a hand. An examination of the 'Hand' routine at the end of the program may help you to understand how the cursor%(0) array is setup.

By selecting 'Arrow' in the cursor menu you may clear the cursor to be edited to a blank. The editor is set to a blank (i. e. no cursor) when the program starts. Select 'Edit Cursor' from the menu. The bit parameters for the screen grid are set up and a blank grid is printed on the screen.

Fig. 2

Now just point and click the mouse to select what the cursor will look like. The program will appear to run a bit slow here while the correct bit is being selected. This takes longer in Basic than in most other languages, so be patient. When the cursor is finished click the OK button.

Now a new grid comes up to create a mask for our new cursor. The cursor mask selects which bits behind the cursor will be allowed to be seen through the cursor (the entire 16X16 grid). The program allows you to exper-iment with different masks until you get it just right. To test it out you can move the cursor over a black area of the screen and then over a white area and see what part of the background is allowed to be seen through the cursor. It is purely subjective so you can keep on trying till you are happy with it. For our example, I have filled in the inside of the cursor to make the mask. Any pixels of the screen which are behind the mask will not be allowed to be displayed. Click the OK button to continue.

Fig. 3 Creating the Mask

Next we set the hot spot of the cursor. The hot spot is the active area of the cursor that determines where it is pointing to. It is the intersection of the corners of the pixels. For our example, we want the hot spot to be at the tip of the pencil so we click there. A small square appears to mark the spot. You may want to try other locations for the hot spot if you don't quite understand the significance of the hot spot. Click OK to continue.

Fig. 4 Setting the Hot Spot

Now the new cursor will appear. WARNING: If the cursor which was defined had no pixels selected (i. e. a blank cursor), then it will be very difficult to select anything from this point on because you will not be able to see the cursor. If this happens you may have to abort (use command-period to halt a basic program). Basic will reinitialize the arrow cursor when you exit the program.

Your new cursor can now be stored in a file on the disk by using the file menu and loaded at a later time. The load routine may be copied for use in your own program to read in a custom cursor for your own programs. After the cursor data is stored to disk, the program will change the file type to "CURS" to enable the load routine to recognize only those files which contain cursor data. Any filename type may be changed so that the routine which reads the data may only select files of the same type.

Hopefully this program provides an easy way to customize your own cursors. A good way to create a library of cursors is to do a screen dump to disk of the MacPaint screen. Then load the dumped sceen and look at the cursors used by MacPaint using Fat Bits and dump each of them to the printer from the Fat Bit screen. Then the cursor can be copied bit by bit into the cursor editor program and saved. The program is available on disk if you don't want to have to type. Have fun!!!

' Cursor Editor
' By Dave Kelly
' ©MACTUTOR 1985

DEFINT i,j,k
DIM Cursor%(34), Bstatus%(512),    Bound0%(256), Bound1%(256), 
 Bound2%(256), Bound3%(256)
editor%=0:NewYork=2:Bold=1
Plain=0:Geneva=3
WINDOW 1,"Cursor Editor", (2,40)-(510,340),1
' Erase BASIC menus
FOR i=3 TO 5:MENU i,0,0,"":NEXT
MENU 1,0,1,"File"
MENU 1,1,1,"Load Cursor"
MENU 1,2,1,"Save Cursor"
MENU 1,3,1,"Quit"
MENU 2,0,1,"Cursor"
MENU 2,1,1,"Edit Cursor"
MENU 2,2,1,"Arrow (Clear Cursor)"
MENU 2,3,1,"Hand"

ON MENU GOSUB Checkmenu: MENU ON
IF editor%=0 THEN MENU STOP:GOSUB  InitEditor:MENU ON
loop:GOTO loop

Checkmenu:
    menunumber=MENU(0)
    menuitem=MENU(1):MENU
    IF menunumber=1 THEN filemenu
    ON menuitem GOSUB     Editor,Arrow,Hand
    RETURN

filemenu:
    ON menuitem GOSUB load.cursor, save.cursor,quit
    RETURN
    

InitEditor:
x=20:y=20:offsetx=0:offsety=0:editor%=1
TEXTFONT(NewYork)
TEXTSIZE(14):TEXTFACE(Bold)
LOCATE 5,1
PRINT"Please wait.... Initializing Editor."
MENU 1,0,0:MENU 2,0,0
FOR i=0 TO 33: cursor%(i)=0:NEXT i
PICTURE ON
FOR j= 0 TO 15
    FOR k=15 TO 0 STEP -1
        rectangle%(0)=y+offsety
        bound0%((j*16)+k)=rectangle%(0)
        rectangle%(1)=x+offsetx
        bound1%((j*16)+k)=rectangle%(1)
        rectangle%(2)=y+offsety+12
        bound2%((j*16)+k)=rectangle%(2)
        rectangle%(3)=x+offsetx+12
        bound3%((j*16)+k)=rectangle%(3)
        bstatus%((j*16)+k)=0
        offsetx=11+offsetx
FRAMERECT(VARPTR(rectangle%(0)))
    NEXT k
    offsety=11+offsety:offsetx=0
NEXT j
PICTURE OFF
grid$=PICTURE$
MENU 1,0,1:MENU 2,0,1:CLS
RETURN

Editor:
    MENU 1,0,0:MENU 2,0,0
   TEXTFONT(NewYork)
   TEXTSIZE(14):TEXTFACE(Bold)
    LOCATE 5,1:PRINT"Please wait for Setup of Editor."
    GOSUB Bitstatus
    
' set up new cursor
    GOSUB print.pic
    LOCATE 2,26:PRINT"Define New   Cursor"
    GOSUB Print.message
    GOSUB Draw.Datapixels
    GOSUB Define
    
' set up new mask
    GOSUB print.pic
    LOCATE 2,26:PRINT"Define New Mask"
    GOSUB Print.message
    GOSUB Draw.Maskpixels
    GOSUB Define
   
 ' set hot spot
    GOSUB print.pic
    LOCATE 2,26:PRINT"Set Hot Spot"
    GOSUB Print.message
    GOSUB define.hotspot
    CLS:BUTTON CLOSE 1
   TEXTFONT(NewYork):TEXTSIZE(14)
    TEXTFACE(Bold)
    LOCATE 5,1:PRINT"Please wait."
    GOSUB Cursor.done
    SETCURSOR (VARPTR(cursor%(0)))
    CLS:MENU 1,0,1:MENU 2,0,1
    RETURN

Print.pic:
    CLS:PICTURE,grid$
    TEXTFONT(NewYork)
    TEXTSIZE(14)
    TEXTFACE(Bold)
    RETURN
    
Print.message:
    TEXTFACE(Plain)
    TEXTSIZE(12)
    LOCATE 4,35:PRINT"Click              to continue"  'Note: Space must 
be ^^^^^ here
    BUTTON 1,1,"OK", (310,40)-(350,80),1
    RETURN

define.hotspot:
    GOSUB Draw.Datapixels
    CALL PENSIZE(4,4):CALL PENMODE(10)
    CALL MOVETO((cursor%(33)*11)+x,  (cursor%(32)*11)+y)
    CALL LINE(0,0)
    WHILE DIALOG(0)<>1
    IF MOUSE(0)>0 THEN GOSUB hotspot
    WEND
    CALL PENNORMAL
    BEEP
    RETURN

hotspot:
    xpos=MOUSE(1):ypos=MOUSE(2)
    IF xpos<x THEN xpos=x
    IF ypos<y THEN ypos=y
    IF xpos>x+16*11 THEN xpos=x+16*11
    IF ypos>y+16*11 THEN ypos=y+16*11

    CALL LINE(0,0)
    cursor%(33)=INT((xpos-x)/11)
    cursor%(32)=INT((ypos-y)/11)
    CALL MOVETO((cursor%(33)*11)+x,  (cursor%(32)*11)+y)
    CALL LINE(0,0)
    RETURN

Draw.Maskpixels:
    maskpixel=1
    FOR i= 256 TO 511
        IF bstatus%(i)=1 THEN rectangle%(0)=bound0%(i-256):    
 rectangle%(1)=bound1%(i-256):     rectangle%(2)=bound2%(i-256): 
 rectangle%(3)=bound3%(i-256):     PAINTRECT(VARPTR            
 (rectangle%(0))): FRAMERECT(VARPTR  (rectangle%(0)))
    NEXT i
    RETURN

Draw.Datapixels:
    maskpixel=0
    FOR i= 0 TO 255
        IF bstatus%(i)=1 THEN rectangle%(0)=bound0%(i):        rectangle%(1)=bound1%(i): 
 rectangle%(2)=bound2%(i):  rectangle%(3)=bound3%(i):          PAINTRECT(VARPTR 
 (rectangle%(0))): FRAMERECT(VARPTR  (rectangle%(0)))
    NEXT i
    RETURN
    
mousepress:
    GOSUB getpixel   'see which pixel is selected
    IF pixel%=256 THEN  RETURN
    IF Bstatus%(Pixel%+maskpixel*256)=0            THEN Bstatus%(Pixel%+ 
 maskpixel*256)=1 ELSE    Bstatus%(Pixel%+         maskpixel*256)=0
    rectangle%(0)=bound0%(Pixel%)
    rectangle%(1)=bound1%(Pixel%)
    rectangle%(2)=bound2%(Pixel%)
    rectangle%(3)=bound3%(Pixel%)
    INVERTRECT(VARPTR(rectangle%(0)))
    FRAMERECT(VARPTR(rectangle%(0)))
    RETURN
    


getpixel:
    Pixel%=256
    FOR i = 0 TO 255
        IF bound0%(i)<MOUSE(2) AND bound2%(i)>MOUSE(2) AND     
 bound1%(i)<MOUSE(1) AND  bound3%(i)>MOUSE(1) THEN             Pixel%=i:i=256
    NEXT i
    RETURN
    
Cursor.done:
    FOR j=0 TO 31
        cursor%(j)=0
        FOR k=14 TO 0 STEP -1
 cursor%(j)=(Bstatus%((j*16)+k)*(2^k))+cursor%(j)
        NEXT k
        IF Bstatus%((j*16)+15)=1 THEN  cursor%(j)=cursor%(j)+&H8000
    NEXT j
    RETURN
    
Define:
    WHILE DIALOG(0)<>1
    IF MOUSE(0)>0 THEN GOSUB  mousepress
    WEND
    BEEP
    RETURN
Bitstatus:
    FOR j=0 TO 31
        t%=cursor%(j)
        FOR k=15  TO 0 STEP -1
            IF t%<0 THEN  Bstatus%((j*16)+k)=1:t%=             t%-&H8000:GOTO 
endloop
            IF t%<2^k THEN  Bstatus%((j*16)+k)=0
            IF t%>=2^k THEN Bstatus%((j*16)+k)=1:t%=           t%-2^k
        endloop:NEXT k
    NEXT j
RETURN
load.cursor:
    filename$=FILES$(1,"CURS")
    IF filename$="" THEN exitload
    OPEN filename$ FOR INPUT AS #1
    FOR i= 0 TO 33
        INPUT #1,cursor%(i)
    NEXT i
    CLOSE #1
exitload:CALL SETCURSOR(VARPTR(cursor%(0)))
    RETURN
save.cursor:
    filename$=FILES$(0)
    IF filename$="" THEN exitsave
    OPEN filename$ FOR OUTPUT AS #1
    FOR i=0 TO 33
        PRINT #1,cursor%(i)
    NEXT i
    CLOSE #1
    NAME filename$ AS filename$,"CURS"
    exitsave:CALL SETCURSOR (VARPTR  (cursor%(0)))
    RETURN
quit:
    BUTTON CLOSE 1:MENU RESET
TEXTFONT(Geneva):TEXTFACE(Plain)
TEXTSIZE(12)
END
Arrow:
    INITCURSOR
    FOR i=0 TO 33: cursor%(i)=0:NEXT i
    RETURN
Hand:
'   Cursor Data
    Cursor%(0)=&H0:Cursor%(1)=&H0
    Cursor%(2)=&H700:Cursor%(3)=&H1900
    Cursor%(4)=&H2200:Cursor%(5)=&H4700
    Cursor%(6)=&HC7FE:Cursor%(7)=&H8C01
    Cursor%(8)=&H97FE:Cursor%(9)=&HE410
Cursor%(10)=&H87E0:Cursor%(11)=&H8420
Cursor%(12)=&HC7C0:Cursor%(13)=&H7F80
    Cursor%(14)=&H0:Cursor%(15)=&H0
'   Cursor Mask
    Cursor%(16)=&H0:Cursor%(17)=&H0
  Cursor%(18)=&H700:Cursor%(19)=&H1F00
Cursor%(20)=&H3E00:Cursor%(21)=&H7F00
Cursor%(22)=&HFFFE:Cursor%(23)=&HFFFF
Cursor%(24)=&HFFFE:Cursor%(25)=&HFFF0
Cursor%(26)=&HFFE0:Cursor%(27)=&HFFE0
Cursor%(28)=&HFFC0:Cursor%(29)=&H7F80
    Cursor%(30)=&H0: Cursor%(31)=&H0
    Cursor%(32)=7      'Vertical hot spot
    Cursor%(33)=16    'Horizontal hot spot
    SETCURSOR(VARPTR(cursor%(0)))
    RETURN