LIBXDOT(3)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
} 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_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 */
} 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
encountered 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)
