;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_hide_mouse proc
     push  bp
     mov   bp,sp

     cmp   [_MouseInstalled],FALSE   ; Make sure our handler is installed
     je    @@Done
     cmp   [_MouseHidden],FALSE      ; If cursor is already hidden exit
     jne   @@Done
     push  si
     push  di

@@WaitEndOfHandler:            ; Make sure handler not currently active
     mov   cl,[inhandler]
     or    cl,cl
     jnz   @@WaitEndOfHandler

     mov   [_MouseHidden],TRUE       ; Delete mouse cursor
     mov   di,[OldScrnOffs]
     mov   ax,[OldY]
     mov   bx,[OldX]
     call  restorebg
     pop   di
     pop   si
@@Done:
     pop   bp
     ret
_x_hide_mouse endp


;----------------------------------------------------------------------
; x_remove_mouse - removes mouse handler
;
; C Prototype
;
;  void x_remove_mouse()
;
; NOTE: This function MUST be called before quitting the program if
;       a mouse handler has been installed
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_mouse_remove proc
    push  bp
    mov   bp,sp
    cmp   [_MouseInstalled],FALSE  ; Check whether we have installed
    je    @@Done                   ;  our mouse handler
    call  _x_hide_mouse
    mov   ax,12                    ; FUNC 12: Install event handler
    xor   cx,cx                    ; Disable all events
    int   33h
    mov   [_MouseInstalled],FALSE
@@Done:
    pop   bp
    ret
_x_mouse_remove endp


;----------------------------------------------------------------------
; x_position_mouse - Positions the mouse cursor at the specified location
;
; C Prototype
;
;  void x_position_mouse(int x, int y)
;
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_position_mouse proc
ARG  X:word,Y:word
     push  bp
     mov   bp,sp

@@WaitEndOfHandler:               ; Make sure handler not currently active
     mov   bl,[inhandler]

     or    bl,bl
     jnz   @@WaitEndOfHandler

     mov   ax,4
     mov   cx,X
     mov   dx,Y
     mov   [_MouseX],cx
     mov   [_MouseY],dx
     shl   cx,1

     mov   [inhandler],1
     int   33h

     ; The handler doesnt get called so need
     ; to update manually;

     cmp   [_MouseHidden],FALSE
     jne   @@NotVisible
     push  di si
     call  update_cursor
     pop   si di

@@NotVisible:
     mov   [inhandler],0
     pop   bp
     ret
_x_position_mouse endp

;----------------------------------------------------------------------
; x_update_mouse - Forces the mouse position to be updated and cursor
;                  to be redrawn.
;
; C Prototype
;
;  void x_update_mouse()
;
; Note this function is useful when you have set "MouseFrozen" to true.
; Allows the cursor position to be updated manually rather than
; automatically by the installed handler.
;
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_update_mouse proc
     push  bp
     mov   bp,sp
     cmp   [_MouseInstalled],FALSE   ; Make sure our handler is installed
     je    @@Done
     cmp   [_MouseHidden],FALSE      ; If cursor is already hidden exit
     jne   @@Done
     push  si
     push  di
     mov   ax,03h                 ; FUNC 3: get cursor pos / button status
     int   33h                    ; Update position variables first
     shr   cx,1
     mov   [_MouseX],cx
     mov   [_MouseY],dx
     mov   [_MouseButtonStatus],bx    ; Update button status
     call  update_cursor
     pop   di
     pop   si
@@Done:
     pop   bp
     ret
_x_update_mouse endp


;----------------------------------------------------------------------
; x_put_cursor - Draws the mouse cursor
;
; C Prototype
;
; void x_put_cursor(int X, int Y, int TopClip, int BottomClip, WORD ScrnOffs)
;
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
ALIGN 2
_x_put_cursor  proc
ARG X:word,Y:word,TopClip,BottomClip,ScrnOffs
LOCAL Height,TopRow,NextLineIncr:word=LocalStk
	push  bp
	mov   bp,sp
	sub   sp,LocalStk                 ; Create space for local variables
	push  si
	push  di
	push  ds
	mov   ax,@data
	mov   ds,ax
	cld

	mov   ax,14                   ; Get image height and save in AX
	mov   bx,Y
	; cx = top Row

	;;;;; CLIP PROCESSING FOR TOP CLIP BORDER ;;;;;;;;;;;;;;;;;;;;;

	mov   dx,[TopClip]            ; Compare u.l. Y coord with Top
	sub   dx,bx                   ; clipping border
	jle   @@NotTopClip            ; jump if  not clipped from above
	cmp   dx,ax
	jnl   @@NotVisible            ; jump if  is completely obscured
	mov   cx,dx
	sub   ax,dx
	add   bx,dx
	jmp   short @@VertClipDone

	;;;; EXIT FOR COMPLETELY OBSCURED  ;;;;;;;;;;;;;;;;;;;;;;

@@NotVisible:
	pop   ds
	pop   di                          ; restore registers
	pop   si
	mov   sp,bp                       ; dealloc local variables
	pop   bp
	ret

	;;;;; CLIP PROCESSING FOR BOTTOM CLIP BORDER ;;;;;;;;;;;;;;;;;;;

@@NotTopClip:
	mov   dx,[BottomClip]
	sub   dx,bx
	js    @@NotVisible
	mov   cx,0
	cmp   dx,ax
	jg    @@VertClipDone
	inc   dx
	mov   ax,dx

@@VertClipDone:

	mov   [Height],ax
	mov   [TopRow],cx

	mov   ax,SCREEN_SEG               ; Point es to VGA segment
	mov   es,ax

	mov   ax,bx
	mov   cx,[_ScrnLogicalByteWidth]  ; Find required screen address
	mul   cx
	mov   di,ax

	sub   cx,3                        ; Distance to next screen row
	mov   [NextLineIncr],cx


	mov   cx,[X]
	mov   bx,cx
	shr   cx,2
	add   di,cx
	and   bx,3
	add   di,[ScrnOffs]

	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


	mov   ax,42
	mul   bx
	mov   si,offset MouseMask
	add   si,ax

	mov   ax,3                        ; Increment DS:BX and DS:SI to
	mul   [TopRow]                    ;  been clipped by the top border
	add   si,ax                       ; by the L.H.S border

	mov   dx,SC_INDEX                 ; Point SC register to map mask
	mov   al,MAP_MASK                 ; in preperation for masking data
	out   dx,al
	inc   dx                          ; Point dx to SC data register
	mov   ah,byte ptr [Height]        ; AH = Scanline loop counter
	mov   bl,[_MouseColor]
@@RowLoop:
	mov   cx,3                        ; Width in bytes across
@@ColLoop:
	lodsb                             ; load plane mask and set MAP MASK
	out   dx,al
	mov   es:[di],bl                  ; store color to specified planes
	inc   di
	loop  @@ColLoop

	add   di,[NextLineIncr]
	dec   ah
	jnz   @@RowLoop

	pop   ds
	pop   di                          ; restore registers
	pop   si
	mov   sp,bp                       ; dealloc local variables
	pop   bp
	ret
_x_put_cursor  endp


;----------------------------------------------------------------------
; getbg - saves cursor background
;
; C Prototype
;
; local function using register parameters
;
; si = screen offset
; ax  = y
; bx  = x
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
ALIGN 2
getbg  proc near

	push  bp
	mov   bp,sp
	push  ds
	cld

	mov   cx,[_ScrnLogicalByteWidth]  ;  by mult. dest Y coord by Screen
	mul   cx                          ;  width then adding screen offset
	add   si,ax                       ; Add Dest Screen Row to di
	sub   cx,3
	shr   bx,2
	add   si,bx
	mov   bx,cx

	mov   di,BGSaveOffs
	mov   ax,SCREEN_SEG               ; Point es to VGA segment
	mov   es,ax
	mov   ds,ax

	mov   dx,GC_INDEX                 ; Set bit mask for all bits from
	mov   ax,BIT_MASK                 ; VGA latches and none from CPU
	out   dx,ax

	mov   dx,SC_INDEX                 ; Point SC register to map mask
	mov   al,MAP_MASK           ; in preperation for masking data
	out   dx,al
	inc   dx
	mov   al,0fh
	out   dx,al

	mov   cx,14
@@Loop:
	movsb
	movsb
	movsb
	add si,bx
	loop @@Loop

mov     dx,GC_INDEX+1 ;restore the bit mask to its default,
	mov     al,0ffh       ; which selects all bits from the CPU
	out     dx,al         ; and none from the latches (the GC
			      ; Index still points to Bit Mask)

	pop   ds
	mov   sp,bp                       ; dealloc local variables
	pop   bp
	ret
getbg  endp

;----------------------------------------------------------------------
; restorebg - restores cursor background
;
; C Prototype
;
; local function using register parameters
;
; di = screen offset
; ax  = y
; bx  = x
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
ALIGN 2
restorebg  proc near
;di = scrn offs
;ax  = y
;bx  = x
	push  bp
	mov   bp,sp
	push  ds
	cld

	mov   cx,[_ScrnLogicalByteWidth]  ;  by mult. dest Y coord by Screen
	mul   cx                          ;  width then adding screen offset
	add   di,ax                       ; Add Dest Screen Row to di
	sub   cx,3
	shr   bx,2
	add   di,bx
	mov   si,BGSaveOffs
	mov   ax,SCREEN_SEG               ; Point es to VGA segment
	mov   es,ax
	mov   ds,ax

	mov   dx,GC_INDEX                 ; Set bit mask for all bits from
	mov   ax,BIT_MASK                 ; VGA latches and none from CPU
	out   dx,ax

	mov   dx,SC_INDEX                 ; Point SC register to map mask
	mov   al,MAP_MASK                 ; in preperation for masking data
	out   dx,al
	inc   dx
	mov   al,0fh
	out   dx,al

	mov   bx,cx
	mov   cx,14
@@Loop:
	movsb
	movsb
	movsb
	add di,bx
	loop @@Loop
	mov  dx,GC_INDEX+1 ;restore the bit mask to its default,
	mov  al,0ffh       ; which selects all bits from the CPU
	out  dx,al         ; and none from the latches (the GC
			   ; Index still points to Bit Mask)
	pop   ds
	pop   bp
	ret
restorebg  endp



;********************** The Mouse event handler *************************

ALIGN 2
mouse_handler proc far
   push  bp
   mov   bp,sp
   push  ds

   mov   di,@data                   ; Make sure DS points to data segment
   mov   ds,di
   cmp   [inhandler],1
   jne   @@NotActive
   pop   ds
   pop   bp
   ret

@@NotActive:
   mov   [inhandler],1
   mov   [_MouseButtonStatus],bx    ; Update button status
   test  ax,1                       ; Is this a motion event ?
   jz    @@Done                     ; No Jump

   shr  cx,1                        ; convert X coord to pixel coords
   mov  [_MouseX],cx                ; save mouse position
   mov  [_MouseY],dx

   cmp  [_MouseHidden],TRUE         ; If mouse hidden dont bother drawing
   je   @@Done

   cmp  [_MouseFrozen],TRUE         ; If mouse hidden dont bother drawing
   je   @@Done

   call update_cursor
@@Done:
   mov  [inhandler],0
   pop  ds
   pop  bp
   ret
mouse_handler endp


end