; DELBOX
;---------------------------------------------------------------
;! Verb to delete boxes with TV cursor & graphics display.
;# VERB TV IMAGING INTERACTIVE
;-----------------------------------------------------------------------
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;;  Associated Universities, Inc. Washington DC, USA.
;;
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;;
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;;
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;-----------------------------------------------------------------------
DELBOX    LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
DELBOX:  Verb to delete boxes with TV cursor & graphics display
GRCHAN         0.0            7.0  Graphics channel to use
GR2CHAN        0.0            7.0  2nd Graphics channel to use
         $    Input and Output adverbs:
NBOXES   $     0.0           50.0  Number of boxes to set 0 => 1
CLBOX    $    -1.0         8192.0  Pixel locations (X,Y) in
         $                         image of lower left corner
         $                         and upper right corner of
         $                         NBOXES windows.

          Uses TV cursor to select the image with which the
          BOXes are associated (if needed).  Other input is from
          TV cursor.  See HELP REBOX or the terminal (during
          execution) for instructions.
----------------------------------------------------------------
REBOX
Type:  verb
Use:   To delete values in the adverb CLBOX using the TV cursor with a
       TV graphics display of the CLBOXes as they are being deleted.
       The terminal will issue instructions.  If there is more than
       one image on the TV, the routine asks the user to point out the
       image with which to convert the input values in CLBOX to TV
       pixels for the initial display of the boxes.  The routine
       begins in a "search" mode.  In this mode, move the cursor to
       any lower left or upper right corner of any rectangular box or
       the center or any point on the circumference of any circular
       box.  Then press button A or B to select that box.  Or push
       button C or D to exit.  The selected box will change color.  If
       that is the box you wish to delete, hit button A and it will
       disappear from the screen and the list and the verb will
       re-enter search mode.  If you do not want to delete the box,
       hit buttons B or C to restore the box to the original color and
       return to search mode.  Hit button D to restore the box and
       exit.  NOTE: all initial boxes do not need to be visible on the
       TV screen (if it is at its full expansion).  Only those that
       are partly or fully visible may be deleted however.
Input/output adverbs:
  GRCHAN......Graphics channel to use for the main display of boxes.
              0 -> 3.
  GR2CHAN.....Graphics channel to use for boxes that are about to be
              deleted.  0 -> GRCHAN+4.
  NBOXES......Number of boxes set before hand and the number set
              afterwards.
  CLBOX.......Input and Output adverb: CLBOX(a,1:NBOXES) where a=1 is
              lower left x pixel, a=2 is lower left y pixel, a=3 is
              upper right x pixel, and a=4 is upper y pixel.  For
              circular boxes, a=1 is -1, a=2 is the radius in pixels,
              a=3 is the center x pixel and a=4 is the center y pixel.
              On input, all must have legitimate values for pixels
              in the image although not necessarily currently displayed
              on the (full screen) TV.
----------------------------------------------------------------
