java.awt.geom
Interface PathIterator

All Known Implementing Classes:
FlatteningPathIterator

public interface PathIterator

This interface provides a directed path over the boundary of a shape. The path can contain 1st through 3rd order Bezier curves (lines, and quadratic and cubic splines). A shape can have multiple disjoint paths via the MOVETO directive, and can close a circular path back to the previos MOVETO via the CLOSE directive.

Since:
1.2
See Also:
Shape, Stroke, FlatteningPathIterator

Field Summary
static int SEG_CLOSE
          The current segment closes a loop by an implicit line to the previous SEG_MOVETO coordinate.
static int SEG_CUBICTO
          The current segment is a cubic parametric curve (more commonly known as a Bezier curve).
static int SEG_LINETO
          The current segment is a line.
static int SEG_MOVETO
          Starts a new subpath.
static int SEG_QUADTO
          The current segment is a quadratic parametric curve.
static int WIND_EVEN_ODD
          The even-odd winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses an odd number of segments.
static int WIND_NON_ZERO
          The non-zero winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses a different number of segments headed clockwise than those headed counterclockwise.
 
Method Summary
 int currentSegment(double[] coords)
          Returns the coordinates of the next point(s), as well as the type of line segment.
 int currentSegment(float[] coords)
          Returns the coordinates of the next point(s), as well as the type of line segment.
 int getWindingRule()
          Returns the winding rule to determine which points are inside this path.
 boolean isDone()
          Tests if the iterator is exhausted.
 void next()
          Advance to the next segment in the iteration.
 

Field Detail

WIND_EVEN_ODD

static final int WIND_EVEN_ODD
The even-odd winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses an odd number of segments.

See Also:
Constant Field Values

WIND_NON_ZERO

static final int WIND_NON_ZERO
The non-zero winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses a different number of segments headed clockwise than those headed counterclockwise.

See Also:
Constant Field Values

SEG_MOVETO

static final int SEG_MOVETO
Starts a new subpath. There is no segment from the previous vertex.

See Also:
Constant Field Values

SEG_LINETO

static final int SEG_LINETO
The current segment is a line.

See Also:
Constant Field Values

SEG_QUADTO

static final int SEG_QUADTO
The current segment is a quadratic parametric curve. It is interpolated as t varies from 0 to 1 over the current point (CP), first control point (P1), and final interpolated control point (P2):
  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)!)
 

See Also:
Constant Field Values

SEG_CUBICTO

static final int SEG_CUBICTO
The current segment is a cubic parametric curve (more commonly known as a Bezier curve). It is interpolated as t varies from 0 to 1 over the current point (CP), first control point (P1), the second control point (P2), and final interpolated control point (P3):
  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)!)
 

See Also:
Constant Field Values

SEG_CLOSE

static final int SEG_CLOSE
The current segment closes a loop by an implicit line to the previous SEG_MOVETO coordinate.

See Also:
Constant Field Values
Method Detail

getWindingRule

int getWindingRule()
Returns the winding rule to determine which points are inside this path.

Returns:
the winding rule
See Also:
WIND_EVEN_ODD, WIND_NON_ZERO

isDone

boolean isDone()
Tests if the iterator is exhausted. If this returns true, currentSegment and next may throw a NoSuchElementException (although this is not required).

Returns:
true if the iteration is complete

next

void next()
Advance to the next segment in the iteration. It is not specified what this does if called when isDone() returns true.

Throws:
NoSuchElementException - optional when isDone() is true

currentSegment

int currentSegment(float[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment. The input array must be at least a float[6], to accomodate up to three (x,y) point pairs (although if you know the iterator is flat, you can probably get by with a float[2]). If the returned type is SEG_MOVETO or SEG_LINETO, the first point in the array is modified; if the returned type is SEG_QUADTO, the first two points are modified; if the returned type is SEG_CUBICTO, all three points are modified; and if the returned type is SEG_CLOSE, the array is untouched.

Parameters:
coords - the array to place the point coordinates in
Returns:
the segment type
Throws:
NullPointerException - if coords is null
ArrayIndexOutOfBoundsException - if coords is too small
NoSuchElementException - optional when isDone() is true
See Also:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, SEG_CLOSE

currentSegment

int currentSegment(double[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment. The input array must be at least a double[6], to accomodate up to three (x,y) point pairs (although if you know the iterator is flat, you can probably get by with a double[2]). If the returned type is SEG_MOVETO or SEG_LINETO, the first point in the array is modified; if the returned type is SEG_QUADTO, the first two points are modified; if the returned type is SEG_CUBICTO, all three points are modified; and if the returned type is SEG_CLOSE, the array is untouched.

Parameters:
coords - the array to place the point coordinates in
Returns:
the segment type
Throws:
NullPointerException - if coords is null
ArrayIndexOutOfBoundsException - if coords is too small
NoSuchElementException - optional when isDone() is true
See Also:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, SEG_CLOSE