NAME
    VideoControl -- Modify the operation of a ViewPort's colormap (v36)

SYNOPSIS
    error = VideoControl( cm , tags )
    d0                    a0   a1

    ULONG VideoControl( struct colormap *, struct tagitem * );

FUNCTION
   process the commands in the videocontrol command tagitem buffer
   using cm as the target, with respect to its "attached" viewport.

   viewport commands:

   VTAG_ATTACH_CM     [_SET        | _GET] -- setget attached viewport
   VTAG_VIEWPORTEXTRA [_SET        | _GET] -- setget attached vp_extra
   VTAG_NORMAL_DISP   [_SET        | _GET] -- setget DisplayInfoHandle
                                                      (natural mode)
   VTAG_COERCE_DISP   [_SET        | _GET] -- setget DisplayInfoHandle
                                                      (coerced mode)

   genlock commands:

   VTAG_BORDERBLANK   [_SET | _CLR | _GET] -- onoffinquire blanking
   VTAG_BORDERNOTRANS [_SET | _CLR | _GET] -- onoffinquire notransparency
   VTAG_CHROMAKEY     [_SET | _CLR | _GET] -- onoffinquire chroma mode
   VTAG_BITPLANEKEY   [_SET | _CLR | _GET] -- onoffinquire bitplane mode
   VTAG_CHROMA_PEN    [_SET | _CLR | _GET] -- setclrget chromakey pen #
   VTAG_CHROMA_PLANE  [_SET |      | _GET] -- setget bitplanekey plane #

   copper commands

   VTAG_USERCLIP      [_SET | _CLR | _GET] -- onoffinquire clipping of
                                              UserCopperList at bottom
                                              edge of ColorMap->cm_vp
                                              (defaults to off)

   buffer commands:

   VTAG_NEXTBUF_CM                         -- link to more VTAG commands
   VTAG_END_CM                             -- terminate command buffer

   batch mode commands:

   (if you want your videocontol taglist to be processed in "batch"
    mode, that is, at the next makevport() for the colormap->cm_vp;
    you may intall a static list of videocontrol TagItems into the
    colormap with the batch_items_set command; and then enable/disable
    batch mode processing of those items via the BATCH_CM control
    command)

   VTAG_BATCH_CM      [_SET | _CLR | _GET] -- onoffinquire batch mode
   VTAG_BATCH_ITEMS   [_SET | _ADD | _GET] -- setaddget batched TagLists

   private commands (used internally by intuition -- do not call):

   VTAG_VPMODEID      [_SET | _CLR | _GET] -- force getvpmodeid() return


INPUTS
    cm   = pointer to struct colormap obtained via getcolormap().
    tags = pointer to a table of videocontrol tagitems.

RESULT
    error = NULL if no error occured in the control operation.
   (non-NULL if bad colormap pointer, no tagitems or bad tag)

    The operating characteristics of the colormap and its attached
    viewport are modified. the result will be incorporated into the
    viewport when its copper lists are reassembled via makevport().

BUGS

SEE ALSO
    graphics/videocontrol.h, getcolormap(), freecolormap()