1LIBXDOT(3) Library Functions Manual LIBXDOT(3)
2
6 libxdot - parsing and deparsing of xdot operations
7
9 #include <graphviz/xdot.h>
10 typedef enum {
12 xd_left, xd_center, xd_right
13 } xdot_align;
14 typedef struct {
16 double x, y, z;
17 } xdot_point;
18 typedef struct {
20 double x, y, w, h;
21 } xdot_rect;
22 typedef struct {
24 int cnt;
25 xdot_point* pts;
26 } xdot_polyline;
27 typedef struct {
29 double x, y;
30 xdot_align align;
31 double width;
32 char* text;
33 } xdot_text;
34 typedef struct {
36 xdot_rect pos;
37 char* name;
38 } xdot_image;
39 typedef struct {
41 double size;
42 char* name;
43 } xdot_font;
44 typedef enum {
46 xd_filled_ellipse, xd_unfilled_ellipse,
47 xd_filled_polygon, xd_unfilled_polygon,
48 xd_filled_bezier, xd_unfilled_bezier,
49 xd_polyline, xd_text,
50 xd_fill_color, xd_pen_color, xd_font, xd_style, xd_image
51 } xdot_kind;
52 typedef enum {
54 xop_ellipse,
55 xop_polygon,
56 xop_bezier,
57 xop_polyline, xop_text,
58 xop_fill_color, xop_pen_color, xop_font, xop_style, xop_image
59 } xop_kind;
60 typedef struct _xdot_op xdot_op;
62 typedef void (*drawfunc_t)(xdot_op*, int);
63 typedef void (*freefunc_t)(xdot_op*);
64 struct _xdot_op {
66 xdot_kind kind;
67 union {
68 xdot_rect ellipse; /* xd_filled_ellipse, xd_unfilled_ellipse */
69 xdot_polyline polygon; /* xd_filled_polygon, xd_unfilled_polygon */
70 xdot_polyline polyline; /* xd_polyline */
71 xdot_polyline bezier; /* xd_filled_bezier, xd_unfilled_bezier */
72 xdot_text text; /* xd_text */
73 xdot_image image; /* xd_image */
74 char* color; /* xd_fill_color, xd_pen_color */
75 xdot_font font; /* xd_font */
76 char* style; /* xd_style */
77 } u;
78 drawfunc_t drawfunc;
79 };
80 #define XDOT_PARSE_ERROR 1
82 typedef struct {
84 int cnt;
85 int sz;
86 xdot_op* ops;
87 freefunc_t freefunc;
88 int flags;
89 } xdot;
90 xdot* parseXDotF (char*, drawfunc_t opfns[], int sz);
92 xdot* parseXDot (char*);
93 char* sprintXDot (xdot*);
94 void fprintXDot (FILE*, xdot*);
95 void freeXDot (xdot*);
96
98 libxdot provides support for parsing and deparsing graphical operations
99 specificed by the xdot language.
100 Types
102 xdot
103 This encapsulates a series of cnt xdot operations, stored in the array
104 pointed to by ops. The sz indicates the size of each item stored in
105 ops. If the user sets the freefunc field, this function will be called
106 on each item in ops during freeXDot before the library does its own
107 clean up of the item. This allows the user to free any resources stored
108 in the item by using an expansion of the xdot_op structure.
109 xdot_op
111 A value of this type represents one xdot operation. The operation is
112 specified by the kind field. The corresponding data is stored in the
113 union u, with the subfield associated with a given kind indicated by
114 the comments.
115 The drawfunc field allows the user to attach a drawing-specific func‐
117 tion to the operation, providing an object-based interface. These func‐
118 tions can be automatically attached during parsing by providing a non-
119 NULL second argument to parseXDotF.
120 xop_kind
122 This type provides an enumeration of the allowed xdot operations. See
123 http://www.graphviz.org/doc/info/output.html#d:xdot
124 for the specific semantics associated with each operation.
125 xdot_rect
127 This represents a rectangle. For ellipses, the x and x fields represent
128 the center of the rectangle, and w and h give the half-width and half-
129 height, respectively. For images, (x,y) gives the lower left corner of
130 the rectangle, and w and h give the width and height, respectively.
131 xdot_polyline
133 This type encapsulates a series of cnt points.
134 xdot_text
136 A value of this type corresponds to printing the string text using the
137 baseline point (x,y). The width field gives an approximation of how
138 wide the printed string will be using the current font and font size.
139 The align field indicates how the text should be horizontally aligned
140 with the point (x,y).
141 xdot_image
143 This denotes the insertion of an image. The image source is given by
144 name. The images is to be placed into the rectangle pos.
145 xdot_font
147 The fields give the name and size, in points, of a font.
148 xdot_align
150 This enumeration type corresponds to the xdot alignment values -1, 0
151 and 1 used with the text operator, or '\l', '\n' and '\r' used in dot
152 text.
153 Functions
155 xdot* parseXDotF (char *str, drawfunc_t* opfns, int sz)
156 Parses the string str as a sequence of xdot operations and returns a
157 pointer to the resulting xdot structure. The function parses as many
158 xdot operations as it can. If some unknown or incorrect input was
159 encountered in str, the ops and cnt fields will reflect the operations
160 parsed before the error, and the XDOT_PARSE_ERROR bit will be set in
161 the flags field. The function returns NULL if it cannot parse any‐
162 thing.
163 If sz is non-zero, it is assumed to be the size of some structure type
165 containing xdot_op as a prefix. In this case, the elements in the array
166 pointed to by ops will each have size sz.
167 If opfns is non-zero, it is taken to be any array of functions indexed
169 by xop_kind. During parsing, the drawfunc member of xop_op will be set
170 to the corresponding function in opfns.
171 xdot* parseXDot (char *str)
173 This is equivalent to parseXDotF(str, 0, 0) .
174 void freeXDot (xdot* xp)
176 This frees the resources associated with the argument. If xp is NULL,
177 nothing happens.
178 extern char* sprintXDot (xdot* xp)
180 extern void fprintXDot (FILE* fp, xdot* xp)
181 These two functions deparse the argument xdot structure, producing a
182 string representation. fprintXDot writes the output onto the open
183 stream fp; sprintXDot returns a heap-allocated string.
184
187 Although some small checking is done on the sz argument to parseXDotF,
188 it is assumed it is a valid value from sizeof applied to some structure
189 type containing xdot_op as its first field. There can be no validation
190 of the opfns argument.
191
193 Emden R. Gansner (erg@research.att.com).
194 31 JULY 2009 LIBXDOT(3)