GPR_$COLOR_ZOOM                   GPR Calls                    GPR_$COLOR_ZOOM


NAME
     gpr_$color_zoom - sets the magnification scale factor for a color
     display.

FORMAT
     gpr_$color_zoom (xfactor, yfactor, status)

DESCRIPTION
     This routine sets the magnification scale factor for a color display.
     The gpr_$color_zoom routine sets the magnification factor for all images
     drawn or BLTed into display memory on certain color nodes.  By default,
     the magnification factor is 1 in the x direction and 1 in the y direc-
     tion, meaning that the system will display graphics in the exact sizes
     you specify.  For example, if you specify a 60 pixel by 60 pixel rectan-
     gle, then the system will display the rectangle as 60 pixels by 60 pix-
     els.  However, if you use gpr_$color_zoom to set the magnification factor
     to 3 in the x direction and 2 in the y direction, then the rectangle will
     be displayed as 180 pixels by 120 pixels.  All future images will also be
     magnified unless you call gpr_$color_zoom a second time to set the mag-
     nification factors back to 1 and 1.

     gpr_$color_zoom uses the integer zoom feature of the color hardware.
     gpr_$color_zoom always zooms from the upper-left corner of the display.
     Even if magnification causes all or part of the image to fall outside the
     bitmap dimensions, no error is returned.

     The gpr_$inq_disp_characteristics routine returns the maximum magnifica-
     tion factors for the target node in the x and y dimensions.

   Input Parameters
     xfactor
          A 2-byte integer that denotes the magnification factor for the x-
          coordinate, in the range 1 through 16.

     yfactor
          A 2-byte integer that denotes the magnification factor for the y-
          coordinate, in the range 1 through 16.

   Output Parameters
     status
          Completion status, in status_$t format.

SEE ALSO
     gpr_$inq_disp_characteristics.

NOTES
     The call only works for programs running on a DN550/560/600/660 color
     node.  If you call gpr_$color_zoom on a monochrome target, the system
     will return the error "Wrong display hardware".

     The DN580/580T nodes also permit limited use of the gpr_$color_zoom call.

     All other nodes do not contain color zoom hardware.  Therefore, if you
     specify values other than 1 for xfactor and yfactor, the system will
     return the error "Wrong display hardware."

     The call only works for programs running in borrow mode.  If you call
     gpr_$color_zoom in a different display mode, the system will return the
     error "Must borrow display for this operation".

     If you specify an xfactor other than 1, then you cannot specify a yfactor
     of 1.  However, if you specify a xfactor of 1, you can specify a yfactor
     other than 1.

     You cannot specify a xfactor or yfactor greater than 2.