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JavaTM 2 Platform Std. Ed. v1.3.1 |
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java.awt.geom
Interface PathIterator
- All Known Implementing Classes:
- FlatteningPathIterator
- public interface PathIterator
The PathIterator interface provides the mechanism
for objects that implement the Shape
interface to return the geometry of their boundary by allowing
a caller to retrieve the path of that boundary a segment at a
time. This interface allows these objects to retrieve the path of
their boundary a segment at a time by using 1st through 3rd order
Bézier curves, which are lines and quadratic or cubic
Bézier splines.
Multiple subpaths can be expressed by using a "MOVETO" segment to create a discontinuity in the geometry to move from the end of one subpath to the beginning of the next.
Each subpath can be closed manually by ending the last segment in
the subpath on the same coordinate as the beginning "MOVETO" segment
for that subpath or by using a "CLOSE" segment to append a line
segment from the last point back to the first.
Be aware that manually closing an outline as opposed to using a
"CLOSE" segment to close the path might result in different line
style decorations being used at the end points of the subpath.
For example, the BasicStroke object
uses a line "JOIN" decoration to connect the first and last points
if a "CLOSE" segment is encountered, whereas simply ending the path
on the same coordinate as the beginning coordinate results in line
"CAP" decorations being used at the ends.
- See Also:
Shape,BasicStroke
| Field Summary | |
static int |
SEG_CLOSE
The segment type constant that specifies that the preceding subpath should be closed by appending a line segment back to the point corresponding to the most recent SEG_MOVETO. |
static int |
SEG_CUBICTO
The segment type constant for the set of 3 points that specify a cubic parametric curve to be drawn from the most recently specified point. |
static int |
SEG_LINETO
The segment type constant for a point that specifies the end point of a line to be drawn from the most recently specified point. |
static int |
SEG_MOVETO
The segment type constant for a point that specifies the starting location for a new subpath. |
static int |
SEG_QUADTO
The segment type constant for the pair of points that specify a quadratic parametric curve to be drawn from the most recently specified point. |
static int |
WIND_EVEN_ODD
The winding rule constant for specifying an even-odd rule for determining the interior of a path. |
static int |
WIND_NON_ZERO
The winding rule constant for specifying a non-zero rule for determining the interior of a path. |
| Method Summary | |
int |
currentSegment(double[] coords)
Returns the coordinates and type of the current path segment in the iteration. |
int |
currentSegment(float[] coords)
Returns the coordinates and type of the current path segment in the iteration. |
int |
getWindingRule()
Returns the winding rule for determining the interior of the path. |
boolean |
isDone()
Tests if the iteration is complete. |
void |
next()
Moves the iterator to the next segment of the path forwards along the primary direction of traversal as long as there are more points in that direction. |
| Field Detail |
WIND_EVEN_ODD
public static final int WIND_EVEN_ODD
- The winding rule constant for specifying an even-odd rule for determining the interior of a path. The even-odd rule specifies that a point lies inside the path if a ray drawn in any direction from that point to infinity is crossed by path segments an odd number of times.
WIND_NON_ZERO
public static final int WIND_NON_ZERO
- The winding rule constant for specifying a non-zero rule for determining the interior of a path. The non-zero rule specifies that a point lies inside the path if a ray drawn in any direction from that point to infinity is crossed by path segments a different number of times in the counter-clockwise direction than the clockwise direction.
SEG_MOVETO
public static final int SEG_MOVETO
- The segment type constant for a point that specifies the starting location for a new subpath.
SEG_LINETO
public static final int SEG_LINETO
- The segment type constant for a point that specifies the end point of a line to be drawn from the most recently specified point.
SEG_QUADTO
public static final int SEG_QUADTO
- The segment type constant for the pair of points that specify
a quadratic parametric curve to be drawn from the most recently
specified point.
The curve is interpolated by solving the parametric control
equation in the range
(t=[0..1])using the most recently specified (current) point (CP), the first control point (P1), and the final interpolated control point (P2). The parametric control equation for this curve is:P(t) = B(2,0)*CP + B(2,1)*P1 + B(2,2)*P2 0 <= t <= 1 B(n,m) = mth coefficient of nth degree Bernstein polynomial = C(n,m) * t^(m) * (1 - t)^(n-m) C(n,m) = Combinations of n things, taken m at a time = n! / (m! * (n-m)!)
SEG_CUBICTO
public static final int SEG_CUBICTO
- The segment type constant for the set of 3 points that specify
a cubic parametric curve to be drawn from the most recently
specified point.
The curve is interpolated by solving the parametric control
equation in the range
(t=[0..1])using the most recently specified (current) point (CP), the first control point (P1), the second control point (P2), and the final interpolated control point (P3). The parametric control equation for this curve is:P(t) = B(3,0)*CP + B(3,1)*P1 + B(3,2)*P2 + B(3,3)*P3 0 <= t <= 1 B(n,m) = mth coefficient of nth degree Bernstein polynomial = C(n,m) * t^(m) * (1 - t)^(n-m) C(n,m) = Combinations of n things, taken m at a time = n! / (m! * (n-m)!)This form of curve is commonly known as a Bézier curve.
SEG_CLOSE
public static final int SEG_CLOSE
- The segment type constant that specifies that the preceding subpath should be closed by appending a line segment back to the point corresponding to the most recent SEG_MOVETO.
| Method Detail |
getWindingRule
public int getWindingRule()
- Returns the winding rule for determining the interior of the
path.
- Returns:
- the winding rule.
- See Also:
WIND_EVEN_ODD,WIND_NON_ZERO
isDone
public boolean isDone()
- Tests if the iteration is complete.
- Returns:
trueif all the segments have been read;falseotherwise.
next
public void next()
- Moves the iterator to the next segment of the path forwards along the primary direction of traversal as long as there are more points in that direction.
currentSegment
public int currentSegment(float[] coords)
- Returns the coordinates and type of the current path segment in
the iteration.
The return value is the path segment type:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
A float array of length 6 must be passed in and can be used to
store the coordinates of the point(s).
Each point is stored as a pair of float x,y coordinates.
SEG_MOVETO and SEG_LINETO types returns one point,
SEG_QUADTO returns two points,
SEG_CUBICTO returns 3 points
and SEG_CLOSE does not return any points.
- Parameters:
coords- an array that holds the data returned from this method- Returns:
- the path segment type of the current path segment.
- See Also:
SEG_MOVETO,SEG_LINETO,SEG_QUADTO,SEG_CUBICTO,SEG_CLOSE
currentSegment
public int currentSegment(double[] coords)
- Returns the coordinates and type of the current path segment in
the iteration.
The return value is the path segment type:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
A double array of length 6 must be passed in and can be used to
store the coordinates of the point(s).
Each point is stored as a pair of double x,y coordinates.
SEG_MOVETO and SEG_LINETO types returns one point,
SEG_QUADTO returns two points,
SEG_CUBICTO returns 3 points
and SEG_CLOSE does not return any points.
- Parameters:
coords- an array that holds the data returned from this method- See Also:
SEG_MOVETO,SEG_LINETO,SEG_QUADTO,SEG_CUBICTO,SEG_CLOSE
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JavaTM 2 Platform Std. Ed. v1.3.1 |
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