


IMVFBQPTR(3IM)         SDSC IMAGE LIBRARY          IMVFBQPTR(3IM)



NAME
     ImVfbQPtr - Query the pointer to a pixel location in a  vir-
     tual frame buffer
     ImVfbQFirst - Query the pointer to the first pixel  location
     in a virtual frame buffer
     ImVfbQLast - Query the pointer to the last pixel location in
     a virtual frame buffer
     ImVfbQLeft - Query the pointer to the next pixel to the left
     in a virtual frame buffer
     ImVfbQRight - Query the pointer to the  next  pixel  to  the
     right in a virtual frame buffer
     ImVfbQUp - Query the pointer to the next pixel up in a  vir-
     tual frame buffer
     ImVfbQDown - Query the pointer to the next pixel down  in  a
     virtual frame buffer
     ImVfbQNext - Query the pointer to the next pixel in  a  vir-
     tual frame buffer
     ImVfbQPrev - Query the pointer to the previous  pixel  in  a
     virtual frame buffer
     ImVfbSInc - Increment the pointer to point to the next pixel
     in a virtual frame buffer
     ImVfbSDec - Decrement the pointer to point to  the  previous
     pixel in a virtual frame buffer

SYNOPSIS
     #include "im.h"

     ImVfbPtr ImVfbQPtr( srcVfb, x, y )
          ImVfb *srcVfb ;
          int x, y ;

     ImVfbPtr ImVfbQFirst( srcVfb )
          ImVfb *srcVfb ;

     ImVfbPtr ImVfbQLast( srcVfb )
          ImVfb *srcVfb ;

     ImVfbPtr ImVfbQLeft( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     ImVfbPtr ImVfbQRight( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     ImVfbPtr ImVfbQUp( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     ImVfbPtr ImVfbQDown( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;



SDSC              Last change: August 25, 1992                  1






IMVFBQPTR(3IM)         SDSC IMAGE LIBRARY          IMVFBQPTR(3IM)



     ImVfbPtr ImVfbQNext( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     ImVfbPtr ImVfbQPrev( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     void ImVfbSInc( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;

     void ImVfbSDec( srcVfb, p )
          ImVfb *srcVfb ;
          ImVfbPtr p ;


DESCRIPTION
     ImVfbQPtr returns the pointer to the _s_r_c_V_f_b pixel at coordi-
     nate (_x,_y).  (0,0) is the upper left corner of the image.

     ImVfbQFirst returns the pointer to the first  pixel  in  the
     _s_r_c_V_f_b and is equivalent to ImVfbQPtr( srcVfb, 0, 0 ).

     ImVfbQLast returns the pointer to  the  last  pixel  in  the
     _s_r_c_V_f_b  and is equivalent to ImVfbQPtr( srcVfb, ImVfbQWidth(
     srcVfb ), ImVfbQHeight( srcVfb ) ).

     ImVfbQLeft returns the pointer to the pixel in  the  _s_r_c_V_f_b,
     just  to the left of the pixel pointed to by _p.  If _p points
     to the left-most  pixel  of  a  scanline,  ImVfbQLeft  wraps
     around to the end of the previous scanline.

     ImVfbQRight returns the pointer to the pixel in the  _s_r_c_V_f_b,
     just to the right of the pixel pointed to by _p.  If _p points
     to the right-most pixel of  a  scanline,  ImVfbQRight  wraps
     around to the start of the next scanline.

     ImVfbQUp returns the pointer to the  pixel  in  the  _s_r_c_V_f_b,
     which is just above the pixel pointed to by _p.

     ImVfbQDown returns the pointer to the pixel in  the  _s_r_c_V_f_b,
     which is just below the pixel pointed to by _p.

     ImVfbQNext returns the pointer to the pixel  in  the  _s_r_c_V_f_b
     just to the right of the pixel pointed to by _p (identical to
     ImVfbQRight).

     ImVfbQPrev returns the pointer to the pixel  in  the  _s_r_c_V_f_b
     just  to the left of the pixel pointed to by _p (identical to
     ImVfbQLeft).




2                 Last change: August 25, 1992               SDSC






IMVFBQPTR(3IM)         SDSC IMAGE LIBRARY          IMVFBQPTR(3IM)



     ImVfbSInc increments pointer _p by one and is equivalent to p
     = ImVfbQNext( srcVfb, p ).

     ImVfbSDec decrements pointer _p by one and is equivalent to p
     = ImVfbQPrev( srcVfb, p ).

NOTES
     The pixel just to the ImVfbQRight of the right-most pixel in
     a scanline is the left-most pixel in the next scanline down.
     The pixel just to the ImVfbQLeft of the left-most pixel in a
     scanline is the last pixel in the previous scanline.

     No automatic wraparound occurs between the  last  pixel  and
     the first pixel in the frame buffer.

     All are C macros.

SEE ALSO
     ImIntro (3IM), ImErrNo (3IM), ImCltQFirst (3IM),  ImCltQLast
     (3IM),  ImCltQNext (3IM), ImCltQPrev (3IM), ImCltQPtr (3IM),
     ImCltSDec (3IM), ImCltSInc (3IM)

AUTHOR
     Mike Bailey
     San Diego Supercomputer Center

CONTACT
     SDSC consultants, (619)534-5100, consult@y1.sdsc.edu



























SDSC              Last change: August 25, 1992                  3



