FIG Format 3.2

This is a description of the Fig Format 3.2, the native file format of XFig.

The new components in protocol 3.2 are the paper size, magnification, single/multiple page indicator and transparent color for GIF export in the header.

The other modification between version 3.1 and version 3.2 of the protocol is the mathematical model used for splines. The new version uses X-splines which allows the user to mix interpolation and approximation points in a same curve. More precisely, it means that an X-spline curve is neither an interpolated spline nor an approximated one, it is BOTH (the behavior of each point is controlled by one single parameter called "shape factor").

For additional information about X-splines, see:

"X-Splines: A Spline Model Designed for the End User"
C. Blanc and C. Schlick,
Proceedings of SIGGRAPH'95

Caveat: Because spline models of previous versions (quadratic B-splines and Bezier with hidden points) are no longer supported, curves that are present in version 3.1 and older files are automatically converted to X-splines. This translation is only an approximation process. It means that the converted curves are not exactly the same as the original ones. Though the translation usually provides almost identical curves, some hand-fitting may be needed in some pathological cases.

Description of the Fig Format

(1) The very first line is a comment line containing the name and version:

#FIG 3.2

The comment line(s) must immediately precede the object to which they are associated. In the case of the "whole figure comments" mentioned below, they immediately precede the (resolution,coord_system) line.

(2) The first non-comment line consists of the following:

Type	Name	Values
string	orientation	"Landscape" or "Portrait"
string	justification	"Center" or "Flush Left"
string	units	"Metric" or "Inches"
string	papersize	"Letter", "Legal", "Ledger", "Tabloid", "A", "B", "C", "D", "E", "A4", "A3", "A2", "A1", "A0" and "B5"
float	magnification	(export and print magnification, %)
string	multiple-page	"Single" or "Multiple" pages
int	transparent color	color number for transparent color for GIF export. -3=background, -2=None, -1=Default, 0-31 for standard colors or 32- for user colors
string	optional comment	An optional set of comment lines, each beginning with a "#", may be here. These are associated with the whole figure
int + int	Fig_resolution + coord_system	Fig units per inch, and and indicator of the coordinate system, with 1 being the origin at lower left corner (NOT USED), and 2 being the origin at upper left

Fig_resolution is the resolution of the figure in the file. Xfig will always write the file with a resolution of 1200ppi, so it will scale the figure upon reading it in if its resolution is different from 1200ppi. Pixels are assumed to be square.

Xfig will read the orientation string and change the canvas to match either the Landscape or Portrait mode of the figure file.

The coordinate_system variable is ignored - the origin is ALWAYS the upper-left corner.

Notes:

• Coordinates are given in "fig_resolution" units.
• Line thicknesses are given in 1/80 inch (0.3175mm) or 1 screen pixel. When exporting to EPS, PostScript or a bitmap format, such as GIF, the line thickness is reduced to 1/160 inch (0.159mm) to "lighten" the look.
• dash-lengths and dot-gaps are given in 80-ths of an inch.

The rest of the file contains various objects. An object can be one of six classes (or types).

• 0, Color pseudo-object.
• 1, Arc.
• 2, Ellipse which is a generalization of circle.
• 3, Polyline which includes polygon and box.
• 4, Spline which includes closed/open approximated/interpolated/x-spline spline.
• 5, Text.
• 6, Compound object which is composed of one or more objects.

In the following elaboration on object formats, every value of fig output are separated by blank characters or new line ('\n'). The value of the unused parameters will be -1.

Some fields are described as "enumeration type" or "bit vector"; the values which these fields can take are defined in the header file object.h. The pen_style field is unused. These values may be defined in some future version of Fig.

The two color fields (pen and fill; pen only, for texts) are defined as follows:

Value	Color
-1	Default
0	Black
1	Blue
2	Green
3	Cyan
4	Red
5	Magenta
6	Yellow
7	White
8	Very dark blue
9	Dark blue
10	Light blue
11	Very light blue
12	Dark green
13	Green
14	Light green
15	Dark cyan
16	Cyan
17	Light cyan
18	Dark red
19	Red
20	Light red
21	Dark magenta
22	Magenta
23	Light magenta
24	Dark brown
25	Brown
26	Light brown
27	Very dark pink
28	Dark pink
29	Light pink
30	Very light pink
31	Gold
32-543	user definable colors

A particular X server may limit the number of colors a user can define.

For WHITE color, the area fill field is defined as follows:

Value	Pattern
-1	not filled
0	black
1 to 19	shades of gray, from darker to lighter
20	white
21-40	not used
41-56	see patterns for colors, below

For BLACK or DEFAULT color, the area fill field is defined as follows:

Value	Pattern
-1	not filled
0	white
1 to 19	shades of gray, from lighter to darker
20	black
21-40	not used
41-56	see patterns for colors, below

For all other colors, the area fill field is defined as follows:

Value	Pattern
-1	not filled
0	black
1 to 19	"shades" of the color, from darker to lighter. A shade is defined as the color mixed with black
20	full saturation of the color
21 to 39	"tints" of the color from the color to white. A tint is defined as the color mixed with white
40	white
41	30 degree left diagonal pattern
42	30 degree right diagonal pattern
43	30 degree crosshatch
44	45 degree left diagonal pattern
45	45 degree right diagonal pattern
46	45 degree crosshatch
47	horizontal bricks
48	vertical bricks
49	horizontal lines
50	vertical lines
51	crosshatch
52	horizontal "shingles" skewed to the right
53	horizontal "shingles" skewed to the left
54	vertical "shingles" skewed one way
55	vertical "shingles"skewed the other way
56	fish scales
57	small fish scales
58	circles
59	hexagons
60	octagons
61	horizontal "tire treads"
62	vertical "tire treads"

The depth field is defined as follows:

Value	Meaning
0 ... 999	a larger value means the object is deeper than (under) objects with smaller depth

The line_style field is defined as follows:

Value	Pattern
-1	Default
0	Solid
1	Dashed
2	Dotted
3	Dash-dotted
4	Dash-double-dotted
5	Dash-triple-dotted

The style_val field is defined as the length, in 1/80 inches, of the on/off dashes for dashed lines, and the distance between the dots, in 1/80 inches, for dotted lines.

The join_style field is defined FOR LINES only as follows:

Value	Meaning
0	Miter
1	Round
2	Bevel

The cap_style field is defined FOR LINES, OPEN SPLINES and ARCS only as follows:

Value	Meaning
0	Butt
1	Round
2	Projecting

The arrow_type field is defined for LINES, ARCS and OPEN SPLINES only as follows:

Value	Meaning
0	Stick type
1	Closed Triangle
2	Closed Triangle with indented butt
3	Closed Triangle with exdented butt

Stick-type arrow:

                  \
                   \
      ______________\
                    /
                   /
                  /
      

Closed triangle arrow:

              |\
              | \
      ________|  \
              |  /
              | /
              |/
      

Closed arrow with "indented" butt:

             |\
             \ \
              \ \
      _________\ \
               / /
              / /
             / /
             |/
      

Closed with "pointed" butt:

                 /\
                /  \
               /    \
      ________/      \
              \      /
               \    /
                \  /
                 \/
      

The arrow_style field is defined for LINES, ARCS and OPEN SPLINES only as follows:

Value	Meaning
0	Hollow (filled with white)
1	Filled with pen color

COLOR PSEUDO OBJECTS:

Color Pseudo-objects define arbitrary colors beyond the 32 standard colors. The color objects must be defined before any other Fig objects.

Type	Name	Description
int	object_code	0
int	color_number	from 32 to 543 (512 total indices available)
hex string	rgb_value	the RGB values, as in #330099

ARC OBJECTS:

Type	Name	Description
int	object_code	(always 5)
int	sub_type	(1=open arc, 2 = closed wedge )
int	line_style	(enumeration type)
int	line_thickness	(1/80 inch)
int	pen_color	(enumeration type, pen color)
int	fill_color	(enumeration type, fill color)
int	depth	(enumeration type)
int	pen_style	(pen style, not used)
int	area_fill	(enumeration type, -1 = no fill)
float	style_val	(1/80 inch)
int	cap_style	(enumeration type)
int	direction	(0: clockwise, 1: counterclockwise)
int	forward_arrow	(0: no forward arrow, 1: on)
int	backward_arrow	(0: no forward arrow, 1: on)
float	center_x, center_y	(center of the arc)
int	x1, y1	(Fig units, the 1st point the user entered)
int	x2, y2	(Fig units, the 2nd point)
int	x3, y3	(Fig units, the last point)

Forward arrow line (Optional; absent if forward_arrow is 0):

Type	Name	Description
int	arrow_type	enumeration type
int	arrow_style	enumeration type
float	arrow_thickness	1/80 inch
float	arrow_width	in Fig units
float	arrow_height	in Fig units

Backward arrow line (Optional; absent if backward_arrow is 0):

Type	Name	Description
int	arrow_type	enumeration type
int	arrow_style	enumeration type
float	arrow_thickness	1/80 inch
float	arrow_width	in Fig units
float	arrow_height	in Fig units

COMPOUND OBJECTS:

A line with object code 6 signifies the start of a compound. There are four more numbers on this line which indicate the upper left corner and the lower right corner of the bounding box of this compound. A line with object code -6 signifies the end of the compound. Compound objects may be nested.

Type	Name	Description
int	object_code	6
int	upperleft_corner_x	in Fig units
int	upperleft_corner_y	in Fig units
int	lowerright_corner_x	in Fig units
int	lowerright_corner_y	in Fig units

Immediately succeeding lines define objects that make up the compound object. The compound object is terminated with a line containing the single value "-6".

ELLIPSE OBJECTS:

Type	Name	Description
int	object_code	1
int	sub_type	1: ellipse defined by radii 2: ellipse defined by diameters 3: circle defined by radius 4: circle defined by diameter)
int	line_style	enumeration type
int	thickness	1/80 inch
int	pen_color	enumeration type
int	fill_color	enumeration type
int	depth	enumeration type
int	pen_style	(not used!)
int	area_fill	enumeration type, -1=no fill
float	style_val	1/80 inch
int	direction	always set this to 1
float	angle	radians, the angle of the x-axis of the ellipse
int	center_x, center_y	Fig units
int	radius_x, radius_y	Fig units
int	start_x, start_y	Fig units, first point entered
int	end_x, end_y	Fig units, last point entered

POLYLINE OBJECTS:

Type	Name	Description
int	object_code	2
int	sub_type	1: polyline, 2: box, 3: polygon, 4: arc-box, 5: imported picture bounding box
int	line_style	(enumeration type)
int	thickness	(1/80 inch)
int	pen_color	(enumeration type, pen color)
int	fill_color	(enumeration type, fill color)
int	depth	(enumeration type)
int	pen_style	(pen style, not used)
int	area_fill	(enumeration type, -1 = no fill)
float	style_val	(1/80 inch)
int	join_style	(enumeration type)
int	cap_style	(enumeration type, only used for POLYLINE)
int	radius	(1/80 inch, radius of arc-boxes)
int	forward_arrow	(0: off, 1: on)
int	backward_arrow	(0: off, 1: on)
int	npoints	(number of points in line)

Forward arrow line: same as for an ARC object

Backward arrow line: same as for an ARC object

Points line:

Type	Name	Description
int	x1,y1	(Fig units)
int	x2,y2	(Fig units)
...	...	...
int	xn,yn	(Fig units)

For polygons and boxes, the last point should be the same as the first one, so that the polyline closes.

PIC line:

Type	Name	Description
boolean	flipped	orientation, normal = 0, flipped = 1
char	file[]	name of picture file to import

SPLINE OBJECTS:

The first line:

Type	Name	Description
int	object_code	3
int	sub_type	0: open approximated spline, 1: closed approximated spline, 2: open interpolated spline, 3: closed interpolated spline, 4: open x-spline, 5: closed x-spline
int	line_style	see end of this section
int	thickness	1/80 inch
int	pen_color	enumeration type
int	fill_color	enumeration type
int	depth	enumeration type
int	pen_style	(not used!)
int	area_fill	enumeration type, -1=no fill
float	style_val	1/80 inch
int	cap_style	enumeration type, only used for open splines
int	foward_arrow	0=off, 1=on
int	backward_arrow	0=off, 1=on
int	npoints	the number of control or data points

Forward arrow line: same as for an ARC object

Backward arrow line: same as for an ARC object

Points line: same as for a POLYLINE object

Control points line : There is one shape factor for each point. The value of this factor must be between -1 (which means that the spline is interpolated at this point) and 1 (which means that the spline is approximated at this point). The spline is always smooth in the neighborhood of a control point, except when the value of the factor is 0 for which there is a first-order discontinuity (i.e. angular point).

TEXT OBJECTS:

Type	Name	Description
int	object_code	4
int	justification	0: Left, 1: Center, 2: Right
int	color	enumeration type
int	depth	enumeration type
int	pen_style	(not used!)
int	font	enumeration type
float	font_size	measured in points
float	angle	measured in radians
int	font_flags	bit vector, see next paragraph
float	height	Fig units
float	length	Fig units
int	x, y	Fig units, origin of the string
char	string[]	ASCII string terminated with '\001'.

If justification = 0, then the (x,y) origin of the string is the lower left corner of the string. If sub_type = 1, it is the lower center. Otherwise it is the lower right corner of the string.

The sequence '\001' is not part of the string. Characters above octal 177 are represented by \xxx where xxx is the octal value. This permits Fig files to be edited with 7-bit editors and sent by e-mail without data loss. Note that the string may contain '\n'.

The font_flags field is defined as follows:

Bit	Description
0	Rigid text (text doesn't scale when scaling compound objects)
1	Special text (for LaTeX)
2	PostScript font (otherwise LaTeX font is used)
3	Hidden text

For font_flags bit 2 = 0 (LaTeX fonts), the font field is defined as:

Value	Meaning
0	Default font
1	Roman
2	Bold
3	Italic
4	Sans Serif
5	Typewriter

For font_flags bit 2 = 1 (PostScript fonts), the font field is defined as:

Value	Font
-1	Default font
0	Times Roman
1	Times Italic
2	Times Bold
3	Times Bold Italic
4	AvantGarde Book
5	AvantGarde Book Oblique
6	AvantGarde Demi
7	AvantGarde Demi Oblique
8	Bookman Light
9	Bookman Light Italic
10	Bookman Demi
11	Bookman Demi Italic
12	Courier
13	Courier Oblique
14	Courier Bold
15	Courier Bold Oblique
16	Helvetica
17	Helvetica Oblique
18	Helvetica Bold
19	Helvetica Bold Oblique
20	Helvetica Narrow
21	Helvetica Narrow Oblique
22	Helvetica Narrow Bold
23	Helvetica Narrow Bold Oblique
24	New Century Schoolbook Roman
25	New Century Schoolbook Italic
26	New Century Schoolbook Bold
27	New Century Schoolbook Bold Italic
28	Palatino Roman
29	Palatino Italic
30	Palatino Bold
31	Palatino Bold Italic
32	Symbol
33	Zapf Chancery Medium Italic
34	Zapf Dingbats

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