% @(#)draw_arro.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:43:32 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      draw_arro.hlq
%.AUTHOR     KB, IPG/ESO
%.KEYWORDS   MIDAS, help files, DRAW/ARROW
%.PURPOSE    On-line help file for the command: DRAW/ARROW
%.VERSION    1.0  06-AUG-1984 : Creation, KB
%.VERSION    1.1  22-JUL-1991 : Update, KB
%----------------------------------------------------------------
\se
SECTION./ARRO
\es\co
DRAW/ARROW						22-JUL-1991  KB
\oc\su
DRAW/ARROW [in_spec] [coord_ref] [draw_opt] [intens] [nocurs] [key_flag]
	draw arrows in the overlay channel
\us\pu
Purpose: 
           Draw arrows in the overlay channel.
\up\sy
Syntax:  
           DRAW/ARROW [in_spec] [coord_ref] [draw_opt] [intens] [nocurs]
                      [key_flag]
\ys\pa
           in_spec = input specification for drawing position;
\\
                (a) CURSOR if coordinates are chosen via the cursor rectangle;
\\
                (b) name of table containing coordinates in columns labeled
                    :XSTART, :YSTART, :XEND and :YEND;
\\
                (c) x1,y1,x2,y2 defining the coords. of start and end of arrow
\\
                (d) name of integer keyword holding the coords, max. 40 values,
                    i.e. 10 arrows, see parameter 'key_flag'
\\
                defaulted to CURSOR
\ap\pa
           coord_ref = F or S, to indicate that coordinates should be
                interpreted as screen pixels or frame coordinates in the usual
                MIDAS syntax, only applicable for option (b) and (c);
                for option (a) and (d) always screen pixels are used;
\\
                defaulted to S, also any "strange" input is interpreted as "S" !
\ap\pa
           draw_opt = direction of arrow, only used, if cursor rectangle input:
\\
                RU for left_down to right_up, RD for left_up to right_down,
                LU for right_down to left_up, LD for right_up to left_down in
                cursor rectangle;
\\
                defaulted to RU, also any "strange" input is interpreted as
                "RU" !
\ap\pa
           intens = color,rotation angle (in degrees) of drawing,
\\
                the arrow-graph is first built up from the specs and in the
                very end rotated counter-clockwise with the rotation angle
\\
                defaulted to WHITE,0.
\ap\pa
           nocurs = no. of cursors to use, if you specify 1, only one cursor is
                used and you have to press ENTER for the start- and endpoint of
                each arrow - overrides the direction given in 'draw_opt';
\\
                defaulted to 2
\ap\pa
           key_flag = K(ey) or N(okey) to indicate that 'in_spec' holds the
                name of an integer keyword which contains the positions for
                up to 10 arrows, the last coord. must be followed by a -1;
\\
               defaulted to N
\ap\see
See also:  
           DRAW/LINE, DRAW/CIRCLE, DRAW/ELLIPS, DRAW/RECTANGLE, DRAW/SLIT
\\
           DRAW/CROSS, DRAW/ANY
\ees\no
Note: 
           The parameters may also be cross referenced via
\\
           INSPEC=, COOREF=, DROPT=, INTENS=, NOCURS= and KEY=
\\
           The following colors are supported (via name or number) in X11:
\\
           Red(3), Green(4), Blue(5), White(2), Black(1), Yellow (6),
           Magenta(7), Cyan(8). All values in [9,255] are interpreted as White.
\\
           If coord_ref = F, a frame must be loaded in the displayed channel.
\\
           The cursor rectangle is moved with the mouse and adjusted in size
           with the arrow keys. Use the ENTER and EXIT buttons on the mouse to
           draw or to exit.
\\
           Due to the redrawing of the cursor rectangle the endpoints of the
           arrow will not have immediately the desired color, but that
           will be corrected, once you exit from the command.
\on\exs
Examples:
\ex
           DRAW/ARROW
             Use cursor rectangle to define endpoints and draw a white arrow
             pointing to the upper right corner.
\xe\ex
           DRAW/ARROW coords F ? red,45.
             Use values from columns :xstart, :ystart, :xend, :yend of table
             `coords.tbl', interpret them as real world coordinates of the
             currently displayed frame and draw arrows in red color;
             finally rotate the arrows around their center by 45.0 degrees
\xe\ex
           DRAW/ARROW 200,200,300,300
             Draw an arrow from the screen pixels (200,200) to (300,300).
\xe \sxe