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LIBXDOT(3)		   Library Functions Manual		    LIBXDOT(3)

NAME
       libxdot - parsing and deparsing of xdot operations

SYNOPSIS
       #include	<graphviz/xdot.h>

       typedef enum {
	   xd_none,
	   xd_linear,
	   xd_radial
       } xdot_grad_type;

       typedef struct {
	   float frac;
	   char* color;
       } xdot_color_stop;

       typedef struct {
	   double x0, y0;
	   double x1, y1;
	   int n_stops;
	   xdot_color_stop* stops;
       } xdot_linear_grad;

       typedef struct {
	   double x0, y0, r0;
	   double x1, y1, r1;
	   int n_stops;
	   xdot_color_stop* stops;
       } xdot_radial_grad;

       typedef struct {
	   xdot_grad_type type;
	   union {
	      char* clr;
	      xdot_linear_grad ling;
	      xdot_radial_grad ring;
	   } u;
       } xdot_color;

       typedef enum {
	   xd_left, xd_center, xd_right
       } xdot_align;

       typedef struct {
	   double x, y,	z;
       } xdot_point;

       typedef struct {
	   double x, y,	w, h;
       } xdot_rect;

       typedef struct {
	   int cnt;
	   xdot_point* pts;
       } xdot_polyline;

       typedef struct {
	 double	x, y;
	 xdot_align align;
	 double	width;
	 char* text;
       } xdot_text;

       typedef struct {
	   xdot_rect pos;
	   char* name;
       } xdot_image;

       typedef struct {
	   double size;
	   char* name;
       } xdot_font;

       typedef enum {
	   xd_filled_ellipse, xd_unfilled_ellipse,
	   xd_filled_polygon, xd_unfilled_polygon,
	   xd_filled_bezier,  xd_unfilled_bezier,
	   xd_polyline,	      xd_text,
	   xd_fill_color,     xd_pen_color, xd_font, xd_style, xd_image,
	   xd_grad_fill_color,	   xd_grad_pen_color,
	   xd_fontchar
       } xdot_kind;

       typedef enum {
	   xop_ellipse,
	   xop_polygon,
	   xop_bezier,
	   xop_polyline,       xop_text,
	   xop_fill_color,     xop_pen_color, xop_font,	xop_style, xop_image,
	   xop_grad_fill_color,	    xop_grad_pen_color,
	   xop_fontchar
       } xop_kind;

       typedef struct _xdot_op xdot_op;
       typedef void (*drawfunc_t)(xdot_op*, int);
       typedef void (*freefunc_t)(xdot_op*);

       struct _xdot_op {
	   xdot_kind kind;
	   union {
	     xdot_rect ellipse;	      /* xd_filled_ellipse, xd_unfilled_ellipse	*/
	     xdot_polyline polygon;   /* xd_filled_polygon, xd_unfilled_polygon	*/
	     xdot_polyline polyline;  /* xd_polyline */
	     xdot_polyline bezier;    /* xd_filled_bezier,  xd_unfilled_bezier */
	     xdot_text text;	      /* xd_text */
	     xdot_image	image;	      /* xd_image */
	     char* color;	      /* xd_fill_color,	xd_pen_color */
	     xdot_color	grad_color;   /* xd_grad_fill_color, xd_grad_pen_color */
	     xdot_font font;	      /* xd_font */
	     char* style;	      /* xd_style */
	     unsigned int fontchar;   /* xd_fontchar */
	   } u;
	   drawfunc_t drawfunc;
       };

       #define XDOT_PARSE_ERROR	1

       typedef struct {
	   int cnt;
	   int sz;
	   xdot_op* ops;
	   freefunc_t freefunc;
	   int flags;
       } xdot;

       xdot* parseXDotF	(char*,	drawfunc_t opfns[], int	sz);
       xdot* parseXDot (char*);
       char* sprintXDot	(xdot*);
       void fprintXDot (FILE*, xdot*);
       void freeXDot (xdot*);

       xdot_grad_type colorType	(char*);
       xdot_color* parseXDotColor (char*);
       void freeXDotColor (xdot_color*);

DESCRIPTION
       libxdot provides	support	for parsing and	deparsing graphical operations
       specificed by the xdot language.

   Types
     xdot
       This encapsulates a series of cnt xdot operations, stored in the	 array
       pointed	to  by	ops.  The sz indicates the size	of each	item stored in
       ops. If the user	sets the freefunc field, this function will be	called
       on  each	 item  in  ops during freeXDot before the library does its own
       clean up	of the item. This allows the user to free any resources	stored
       in the item by using an expansion of the	xdot_op	structure.

     xdot_op
       A  value	 of  this type represents one xdot operation. The operation is
       specified by the	kind field. The	corresponding data is  stored  in  the
       union  u,  with	the subfield associated	with a given kind indicated by
       the comments.

       The drawfunc field allows the user to attach a  drawing-specific	 func-
       tion to the operation, providing	an object-based	interface. These func-
       tions can be automatically attached during parsing by providing a  non-
       NULL second argument to parseXDotF.

     xop_kind
       This type provides an enumeration of the	allowed	xdot operations.  See
	   http://www.graphviz.org/doc/info/output.html#d:xdot
       for the specific	semantics associated with each operation.

     xdot_rect
       This represents a rectangle. For	ellipses, the x	and x fields represent
       the center of the rectangle, and	w and h	give the half-width and	 half-
       height, respectively.  For images, (x,y)	gives the lower	left corner of
       the rectangle, and w and	h give the width and height, respectively.

     xdot_polyline
       This type encapsulates a	series of cnt points.

     xdot_text
       A value of this type corresponds	to printing the	string text using  the
       baseline	 point	(x,y).	 The width field gives an approximation	of how
       wide the	printed	string will be using the current font and  font	 size.
       The  align  field indicates how the text	should be horizontally aligned
       with the	point (x,y).

     xdot_image
       This denotes the	insertion of an	image. The image source	 is  given  by
       name. The images	is to be placed	into the rectangle pos.

     xdot_font
       The fields give the name	and size, in points, of	a font.

     xdot_align
       This  enumeration  type	corresponds to the xdot	alignment values -1, 0
       and 1 used with the text	operator, or '\l', '\n'	and '\r' used  in  dot
       text.

   Functions
     xdot* parseXDotF (char *str, drawfunc_t* opfns, int sz)
       Parses  the  string  str	as a sequence of xdot operations and returns a
       pointer to the resulting	xdot structure.	 The function parses  as  many
       xdot  operations	 as it can. If some unknown or incorrect input was en-
       countered in str, the ops and cnt fields	will  reflect  the  operations
       parsed  before  the  error, and the XDOT_PARSE_ERROR bit	will be	set in
       the flags field.	 The function returns NULL if  it  cannot  parse  any-
       thing.

       If  sz is non-zero, it is assumed to be the size	of some	structure type
       containing xdot_op as a prefix. In this case, the elements in the array
       pointed to by ops will each have	size sz.

       If  opfns is non-zero, it is taken to be	any array of functions indexed
       by xop_kind. During parsing, the	drawfunc member	of xop_op will be  set
       to the corresponding function in	opfns.

     xdot* parseXDot (char *str)
       This is equivalent to parseXDotF(str, 0,	0) .

     void freeXDot (xdot* xp)
       This  frees the resources associated with the argument.	If xp is NULL,
       nothing happens.

     extern char* sprintXDot (xdot* xp)
     extern void fprintXDot (FILE* fp, xdot* xp)
       These two functions deparse the argument	xdot  structure,  producing  a
       string  representation.	fprintXDot  writes  the	 output	 onto the open
       stream fp; sprintXDot returns a heap-allocated string.

       The color string	with fill and draw operations can  encode  linear  and
       radial  gradients.  These values	are parsed automatically by parseXDotF
       or  parseXDot,  with   xdot_op	having	 kind	xd_grad_pen_color   or
       xd_grad_fill_color and the value	is stored in grad_color.

       For  an	application  that handles its own parsing of xdot, the library
       provides	three helper functions.

     xdot_grad_type colorTypeXDot (char	*str)
       returns the color type described	by the input string.

     char* parseXDotColor (char	*str, xdot_color* clr)
       attempts	to parse the string str	as a color value, storing  the	result
       in clr. It returns NULL on failure.

     void freeXDotColor	(xdot_color* cp)
       This frees the resources	associated with	a value	of type	xdot_color.

BUGS
       Although	 some small checking is	done on	the sz argument	to parseXDotF,
       it is assumed it	is a valid value from sizeof applied to	some structure
       type  containing	xdot_op	as its first field. There can be no validation
       of the opfns argument.

AUTHORS
       Emden R.	Gansner	(erg@research.att.com).

				 31 JULY 2009			    LIBXDOT(3)

NAME | SYNOPSIS | DESCRIPTION | BUGS | AUTHORS

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