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.
java.awt.Shape
, java.awt.BasicStroke
Modifier and Type | Field and Description |
---|---|
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. |
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. |
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. |
public static final int | SEG_MOVETO
The segment type constant for a point that specifies the starting location for a new subpath. |
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. |
public static final int | WIND_EVEN_ODD
The winding rule constant for specifying an even-odd rule for determining the interior of a path. |
public static final int | WIND_NON_ZERO
The winding rule constant for specifying a non-zero rule for determining the interior of a path. |
Modifier and Type | Method and Description |
---|---|
public int | Returns: the path-segment type of the current path segment.an array that holds the data returned from
this method coords)Returns the coordinates and type of the current path segment in the iteration. |
public int | Returns: the winding rule.Returns the winding rule for determining the interior of the path. |
public boolean | Returns: true if all the segments have
been read; false otherwise.Tests if the iteration is complete. |
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. |
SEG_CLOSE | back to summary |
---|---|
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. |
SEG_CUBICTO | back to summary |
---|---|
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 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_LINETO | back to summary |
---|---|
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_MOVETO | back to summary |
---|---|
public static final int SEG_MOVETO The segment type constant for a point that specifies the starting location for a new subpath. |
SEG_QUADTO | back to summary |
---|---|
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 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)!) |
WIND_EVEN_ODD | back to summary |
---|---|
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 | back to summary |
---|---|
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. |
currentSegment | back to summary |
---|---|
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.
|
getWindingRule | back to summary |
---|---|
public int getWindingRule() Returns the winding rule for determining the interior of the path.
|
isDone | back to summary |
---|---|
public boolean isDone() Tests if the iteration is complete.
|
next | back to summary |
---|---|
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. |