PathIterator JDK 1.6)

Description

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

Methods

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public int currentSegment (double[] coords)

Returns the coordinates and type of the current path segment in the iteration.

public int currentSegment (float[] coords)

Returns the coordinates and type of the current path segment in the iteration.

public int getWindingRule ()

Returns the winding rule for determining the interior of the path.

public boolean isDone ()

Tests if the iteration is complete.

Tests if the iteration is complete.
Returns: true if all the segments have been read; false otherwise.

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.

Fields

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publicfinalstatic int SEG_CLOSE = "4"

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.

publicfinalstatic int SEG_CUBICTO = "3"

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 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.

publicfinalstatic int SEG_LINETO = "1"

The segment type constant for a point that specifies the end point of a line to be drawn from the most recently specified point.

publicfinalstatic int SEG_MOVETO = "0"

The segment type constant for a point that specifies the starting location for a new subpath.

publicfinalstatic int SEG_QUADTO = "2"

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 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)!)

publicfinalstatic int WIND_EVEN_ODD = "0"

The winding rule constant for specifying an even-odd rule for determining the interior of a path.

publicfinalstatic int WIND_NON_ZERO = "1"

The winding rule constant for specifying a non-zero rule for determining the interior of a path.