\cancel mode verify
! box.jnl - draw a box using the indicated corners
! 8/94
! 1/03 bug fix: with v5.5 Ferret, possible negative numbers in arguments 
!               need to be in parentheses within the IF THEN statements

! Description: Overlay a colored box outline given the corner coordinates

! usage:  GO box xlo xhi ylo yhi [pen_number]

! Notes:
!  1) use  GO line_samples    to view the first 6 pen numbers
!       Higher pen numbers cycle with thicker lines (max 18)

! test pen_number before performing any actions
query/ignore $1%<Usage: GO box xlo xhi ylo yhi [pen_number]%
query/ignore $2%<Usage: GO box xlo xhi ylo yhi [pen_number]%
query/ignore $3%<Usage: GO box xlo xhi ylo yhi [pen_number]%
query/ignore $4%<Usage: GO box xlo xhi ylo yhi [pen_number]%
query/ignore $5%1|red>1|green>1|blue>1|thick>1|0>1|1>1|2>1|3>1|4>1|5>1|6>1|7>1|8>1|9>1|10>1|11>1|12>1|13>1|14>1|15>1|16>1|17>1|18>1|<GO box xlo xhi ylo yhi pen with pen = 0(back), 1(fore), thick, 2-18 or a color%

LET/QUIET XBOX_CORNERS = IF I LE 2 THEN (($1)) ELSE XBOX_CORNER2
LET/QUIET XBOX_CORNER2 = IF I LE 4 THEN (($2)) ELSE ($1)
LET/QUIET YBOX_CORNERS = IF I EQ 1 THEN (($4)) ELSE YBOX_CORNER2
LET/QUIET YBOX_CORNER2 = IF I LE 3 THEN (($3)) ELSE ($4)

! set up PLOT+
PLOT/VS/NOLAB/OVER/line=1/SET_UP/I=1:5 XBOX_CORNERS, YBOX_CORNERS

! select line style
! Note: The "line=" could be used to specify the line style but the command
!       gets too ungainly to read
ppl pen 1,$5"1|red>2|green>3|blue>4|thick>7|0>0|1>1|2>2|3>3|4>4|5>5|6>6|7>7|8>8|9>9|10>10|11>11|12>12|13>13|14>14|15>15|16>16|17>17|18>18|"

! plot it
PPL PLOT/OVERLAY

! clean up
ppl pen 1,1
set mode/last verify