GnomeCanvasLine
represents one or more line segments joined at their
endpoints. You can use it to represent an unfilled
polygon as well.
GnomeCanvasPolygon is used for filled polygons.
A line is specified using a
GnomeCanvasPoints structure, which looks like
this:
typedef struct {
int num_points;
double *coords;
int ref_count;
} GnomeCanvasPoints;
|
The coords field contains
an array of points, alternating X and Y coordinates. You
fill the coords array
directly, after creating a
GnomeCanvasPoints with
gnome_canvas_points_new(); the structure should be
destroyed with
gnome_canvas_points_unref().
Lines can have arrowheads on either end; the arrowhead
shape is specified via three parameters, arbitrarily
named A, B, and C. Parameter A (specified with the arrow_shape_a argument)
specifies the distance from the base of the arrowhead to
the tip. B specifies the distance from the tip of the
arrowhead to one of the trailing points; C specifies the
distance of a trailing point from the outer edge of the
line.
Table 2.
GnomeCanvasLine Arguments
|
Name
|
Type
|
Read/Write
|
Description
|
|
points
|
GnomeCanvasPoints*
|
Both
|
Points in the line
|
|
fill_color
|
gchar*
|
Write-only
|
Fill color; string for
gdk_color_parse()
|
|
fill_color_gdk
|
GdkColor*
|
Both
|
Fill color; specified as already-allocated GdkColor
|
|
fill_color_rgba
|
guint32
|
Both
|
Fill color; specified as 32-bit value packing red,
green, blue, and alpha into bytes 1, 2, 3, and 4;
alpha of 255 is opaque, 0 is invisible
|
|
fill_stipple
|
GdkBitmap*
|
Both
|
Stipple to use when drawing line; GDK mode only
|
|
width_pixels
|
guint
|
Write-only
|
Width of the line, in pixels (independent of zoom)
|
|
width_units
|
double
|
Write-only
|
Width of the line, in canvas units; pixel width
changes with zoom factor (pixels per unit)
|
|
cap_style
|
GdkCapStyle
|
Both
|
Cap style (GDK mode only)
|
|
join_style
|
GdkJoinStyle
|
Both
|
Join style (GDK mode only)
|
|
line_style
|
GdkLineStyle
|
Both
|
Line style (GDK mode only)
|
|
first_arrowhead
|
gboolean
|
Both
|
Whether to put an arrowhead at the start of the
line
|
|
last_arrowhead
|
gboolean
|
Both
|
Whether to put an arrowhead at the end of the line
|
|
smooth
|
gboolean
|
Both
|
Whether to smooth the line using parabolic splines
|
|
spline_steps
|
guint
|
Both
|
Number of steps to use when rendering curves
|
|
arrow_shape_a
|
double
|
Both
|
Length of arrowhead
|
|
arrow_shape_b
|
double
|
Both
|
Length of arrowhead edges (tip to trailing points)
|
|
arrow_shape_c
|
double
|
Both
|
Width of arrowhead
|
