com.codename1.ui.geom

Interface PathIterator

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 SEG_MOVETO directive, and can close a circular path back to the previous SEG_MOVETO via the SEG_CLOSE directive.

Author:

shannah

See Also:

GeneralPath, Shape, Graphics.drawShape(com.codename1.ui.geom.Shape, com.codename1.ui.Stroke), Graphics.fillShape(com.codename1.ui.geom.Shape)

Field Summary

Fields

Modifier and Type	Field and Description
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

Modifier and Type	Method and Description
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. (WIND_EVEN_ODD or WIND_NON_ZERO).

isDone

boolean isDone()

Tests if the iterator is exhausted. If this returns true, currentSegment and next may throw a RuntimeException (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.

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 accommodate 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. One of (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 accommodate 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. One of (SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, SEG_CLOSE).