CHAPTER 4
226
Graphics
The path currently under construction is called the
current path.
In PDF (unlike
PostScript), the current path is
not
part of the graphics state and is
not
saved and
restored along with the other graphics state parameters. PDF paths are strictly in-
ternal objects with no explicit representation. Once a path has been painted, it is
no longer defined; there is then no current path until a new one is begun with the
m
or
re
operator.
The trailing endpoint of the segment most recently added to the current path is
referred to as the
current point.
If the current path is empty, the current point is
undefined. Most operators that add a segment to the current path start at the cur-
rent point; if the current point is undefined, an error is generated.
noting coordinates in user space.
TABLE 4.9 Path construction operators
OPERANDS
OPERATOR
DESCRIPTION
x y
m
Begin a new subpath by moving the current point to coordinates
(
x
,
y
), omitting any connecting line segment. If the previous path
construction operator in the current path was also
m
, the new
m
overrides it; no vestige of the previous
m
operation remains in the
path.
Append a straight line segment from the current point to the point
(
x
,
y
). The new current point is (
x
,
y
).
Append a cubic Bézier curve to the current path. The curve extends
from the current point to the point (
x
3
,
y
3
), using (
x
1
,
y
1
) and
(
x
2
,
y
2
) as the Bézier control points (see “Cubic Bézier Curves,” be-
x
3
,
y
3
).
Append a cubic Bézier curve to the current path. The curve extends
from the current point to the point (
x
3
,
y
3
), using the current point
and (
x
2
,
y
2
) as the Bézier control points (see “Cubic Bézier Curves,”
x
3
,
y
3
).
Append a cubic Bézier curve to the current path. The curve extends
from the current point to the point (
x
3
,
y
3
), using (
x
1
,
y
1
) and
(
x
3
,
y
3
) as the Bézier control points (see “Cubic Bézier Curves,” be-
x
3
,
y
3
).
x y
l
(lowercase
L
)
x
1
y
1
x
2
y
2
x
3
y
3
c
x
2
y
2
x
3
y
3
v
x
1
y
1
x
3
y
3
y