/*
* Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package java.awt.geom;
import java.util.*;
/**
* A utility class to iterate over the path segments of an ellipse
* through the PathIterator interface.
*
* @author Jim Graham
*/
class
EllipseIterator implements
PathIterator {
double
x,
y,
w,
h;
AffineTransform affine;
int
index;
EllipseIterator(
Ellipse2D e,
AffineTransform at) {
this.
x =
e.
getX();
this.
y =
e.
getY();
this.
w =
e.
getWidth();
this.
h =
e.
getHeight();
this.
affine =
at;
if (
w < 0 ||
h < 0) {
index = 6;
}
}
/**
* Return the winding rule for determining the insideness of the
* path.
* @see #WIND_EVEN_ODD
* @see #WIND_NON_ZERO
*/
public int
getWindingRule() {
return
WIND_NON_ZERO;
}
/**
* Tests if there are more points to read.
* @return true if there are more points to read
*/
public boolean
isDone() {
return
index > 5;
}
/**
* 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.
*/
public void
next() {
index++;
}
// ArcIterator.btan(Math.PI/2)
public static final double
CtrlVal = 0.5522847498307933;
/*
* ctrlpts contains the control points for a set of 4 cubic
* bezier curves that approximate a circle of radius 0.5
* centered at 0.5, 0.5
*/
private static final double
pcv = 0.5 +
CtrlVal * 0.5;
private static final double
ncv = 0.5 -
CtrlVal * 0.5;
private static double
ctrlpts[][] = {
{ 1.0,
pcv,
pcv, 1.0, 0.5, 1.0 },
{
ncv, 1.0, 0.0,
pcv, 0.0, 0.5 },
{ 0.0,
ncv,
ncv, 0.0, 0.5, 0.0 },
{
pcv, 0.0, 1.0,
ncv, 1.0, 0.5 }
};
/**
* 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 may 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 will return one point,
* SEG_QUADTO will return two points,
* SEG_CUBICTO will return 3 points
* and SEG_CLOSE will not return any points.
* @see #SEG_MOVETO
* @see #SEG_LINETO
* @see #SEG_QUADTO
* @see #SEG_CUBICTO
* @see #SEG_CLOSE
*/
public int
currentSegment(float[]
coords) {
if (
isDone()) {
throw new
NoSuchElementException("ellipse iterator out of bounds");
}
if (
index == 5) {
return
SEG_CLOSE;
}
if (
index == 0) {
double
ctrls[] =
ctrlpts[3];
coords[0] = (float) (
x +
ctrls[4] *
w);
coords[1] = (float) (
y +
ctrls[5] *
h);
if (
affine != null) {
affine.
transform(
coords, 0,
coords, 0, 1);
}
return
SEG_MOVETO;
}
double
ctrls[] =
ctrlpts[
index - 1];
coords[0] = (float) (
x +
ctrls[0] *
w);
coords[1] = (float) (
y +
ctrls[1] *
h);
coords[2] = (float) (
x +
ctrls[2] *
w);
coords[3] = (float) (
y +
ctrls[3] *
h);
coords[4] = (float) (
x +
ctrls[4] *
w);
coords[5] = (float) (
y +
ctrls[5] *
h);
if (
affine != null) {
affine.
transform(
coords, 0,
coords, 0, 3);
}
return
SEG_CUBICTO;
}
/**
* 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 may 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 will return one point,
* SEG_QUADTO will return two points,
* SEG_CUBICTO will return 3 points
* and SEG_CLOSE will not return any points.
* @see #SEG_MOVETO
* @see #SEG_LINETO
* @see #SEG_QUADTO
* @see #SEG_CUBICTO
* @see #SEG_CLOSE
*/
public int
currentSegment(double[]
coords) {
if (
isDone()) {
throw new
NoSuchElementException("ellipse iterator out of bounds");
}
if (
index == 5) {
return
SEG_CLOSE;
}
if (
index == 0) {
double
ctrls[] =
ctrlpts[3];
coords[0] =
x +
ctrls[4] *
w;
coords[1] =
y +
ctrls[5] *
h;
if (
affine != null) {
affine.
transform(
coords, 0,
coords, 0, 1);
}
return
SEG_MOVETO;
}
double
ctrls[] =
ctrlpts[
index - 1];
coords[0] =
x +
ctrls[0] *
w;
coords[1] =
y +
ctrls[1] *
h;
coords[2] =
x +
ctrls[2] *
w;
coords[3] =
y +
ctrls[3] *
h;
coords[4] =
x +
ctrls[4] *
w;
coords[5] =
y +
ctrls[5] *
h;
if (
affine != null) {
affine.
transform(
coords, 0,
coords, 0, 3);
}
return
SEG_CUBICTO;
}
}