com.sun.javafx.geom.EllipseIterator Maven / Gradle / Ivy
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/*
* Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package com.sun.javafx.geom;
import java.util.NoSuchElementException;
import com.sun.javafx.geom.transform.BaseTransform;
/**
* A utility class to iterate over the path segments of an ellipse
* through the PathIterator interface.
*
* @version 10 Feb 1997
*/
class EllipseIterator implements PathIterator {
double x, y, w, h;
BaseTransform transform;
int index;
EllipseIterator(Ellipse2D e, BaseTransform tx) {
this.x = e.x;
this.y = e.y;
this.w = e.width;
this.h = e.height;
this.transform = tx;
if (w < 0f || h < 0f) {
index = 6;
}
}
/**
* Return the winding rule for determining the insideness of the
* path.
* @see #WIND_EVEN_ODD
* @see #WIND_NON_ZERO
*/
@Override
public int getWindingRule() {
return WIND_NON_ZERO;
}
/**
* Tests if there are more points to read.
* @return true if there are more points to read
*/
@Override
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.
*/
@Override
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 final 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
*/
@Override
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 (transform != null) {
transform.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 (transform != null) {
transform.transform(coords, 0, coords, 0, 3);
}
return SEG_CUBICTO;
}
}