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products/sources/formale Sprachen/Java/Openjdk/src/java.desktop/share/classes/java/awt/ (Sun/Oracle ^©) Datei vom 13.11.2022 mit Größe 23 kB

Quelle Polygon.java Sprache: JAVA

/*
* Copyright (c) 1995, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* 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 java.awt;

import java.awt.geom.AffineTransform;
import java.awt.geom.PathIterator;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.io.Serial;
import java.util.Arrays;

import sun.awt.geom.Crossings;

/**
* The {@code Polygon} class encapsulates a description of a
* closed, two-dimensional region within a coordinate space. This
* region is bounded by an arbitrary number of line segments, each of
* which is one side of the polygon. Internally, a polygon
* comprises of a list of {@code (x,y)}
* coordinate pairs, where each pair defines a vertex of the
* polygon, and two successive pairs are the endpoints of a
* line that is a side of the polygon. The first and final
* pairs of {@code (x,y)} points are joined by a line segment
* that closes the polygon. This {@code Polygon} is defined with
* an even-odd winding rule. See
* {@link java.awt.geom.PathIterator#WIND_EVEN_ODD WIND_EVEN_ODD}
* for a definition of the even-odd winding rule.
* This class's hit-testing methods, which include the
* {@code contains}, {@code intersects} and {@code inside}
* methods, use the insideness definition described in the
* {@link Shape} class comments.
*
* @author Sami Shaio
* @see Shape
* @author Herb Jellinek
* @since 1.0
*/
public class Polygon implements Shape, java.io.Serializable {

 /**
 * The total number of points. The value of {@code npoints}
 * represents the number of valid points in this {@code Polygon}
 * and might be less than the number of elements in
 * {@link #xpoints xpoints} or {@link #ypoints ypoints}.
 * This value can be 0.
 *
 * @serial
 * @see #addPoint(int, int)
 * @since 1.0
 */
 public int npoints;

 /**
 * The array of X coordinates. The number of elements in
 * this array might be more than the number of X coordinates
 * in this {@code Polygon}. The extra elements allow new points
 * to be added to this {@code Polygon} without re-creating this
 * array. The value of {@link #npoints npoints} is equal to the
 * number of valid points in this {@code Polygon}.
 *
 * @serial
 * @see #addPoint(int, int)
 * @since 1.0
 */
 public int[] xpoints;

 /**
 * The array of Y coordinates. The number of elements in
 * this array might be more than the number of Y coordinates
 * in this {@code Polygon}. The extra elements allow new points
 * to be added to this {@code Polygon} without re-creating this
 * array. The value of {@code npoints} is equal to the
 * number of valid points in this {@code Polygon}.
 *
 * @serial
 * @see #addPoint(int, int)
 * @since 1.0
 */
 public int[] ypoints;

 /**
 * The bounds of this {@code Polygon}.
 * This value can be null.
 *
 * @serial
 * @see #getBoundingBox()
 * @see #getBounds()
 * @since 1.0
 */
 protected Rectangle bounds;

 /**
 * Use serialVersionUID from JDK 1.1 for interoperability.
 */
 @Serial
 private static final long serialVersionUID = -6460061437900069969L;

 /*
 * Default length for xpoints and ypoints.
 */
 private static final int MIN_LENGTH = 4;

 /**
 * Creates an empty polygon.
 * @since 1.0
 */
 public Polygon() {
 xpoints = new int[MIN_LENGTH];
 ypoints = new int[MIN_LENGTH];
 }

 /**
 * Constructs and initializes a {@code Polygon} from the specified
 * parameters.
 * @param xpoints an array of X coordinates
 * @param ypoints an array of Y coordinates
 * @param npoints the total number of points in the
 * {@code Polygon}
 * @throws NegativeArraySizeException if the value of
 * {@code npoints} is negative.
 * @throws IndexOutOfBoundsException if {@code npoints} is
 * greater than the length of {@code xpoints}
 * or the length of {@code ypoints}.
 * @throws NullPointerException if {@code xpoints} or
 * {@code ypoints} is {@code null}.
 * @since 1.0
 */
 public Polygon(int[] xpoints, int[] ypoints, int npoints) {
 // Fix 4489009: should throw IndexOutOfBoundsException instead
 // of OutOfMemoryError if npoints is huge and > {x,y}points.length
 if (npoints > xpoints.length || npoints > ypoints.length) {
 throw new IndexOutOfBoundsException("npoints > xpoints.length || "+
 "npoints > ypoints.length");
 }
 // Fix 6191114: should throw NegativeArraySizeException with
 // negative npoints
 if (npoints < 0) {
 throw new NegativeArraySizeException("npoints < 0");
 }
 // Fix 6343431: Applet compatibility problems if arrays are not
 // exactly npoints in length
 this.npoints = npoints;
 this.xpoints = Arrays.copyOf(xpoints, npoints);
 this.ypoints = Arrays.copyOf(ypoints, npoints);
 }

 /**
 * Resets this {@code Polygon} object to an empty polygon.
 * The coordinate arrays and the data in them are left untouched
 * but the number of points is reset to zero to mark the old
 * vertex data as invalid and to start accumulating new vertex
 * data at the beginning.
 * All internally-cached data relating to the old vertices
 * are discarded.
 * Note that since the coordinate arrays from before the reset
 * are reused, creating a new empty {@code Polygon} might
 * be more memory efficient than resetting the current one if
 * the number of vertices in the new polygon data is significantly
 * smaller than the number of vertices in the data from before the
 * reset.
 * @see java.awt.Polygon#invalidate
 * @since 1.4
 */
 public void reset() {
 npoints = 0;
 bounds = null;
 }

 /**
 * Invalidates or flushes any internally-cached data that depends
 * on the vertex coordinates of this {@code Polygon}.
 * This method should be called after any direct manipulation
 * of the coordinates in the {@code xpoints} or
 * {@code ypoints} arrays to avoid inconsistent results
 * from methods such as {@code getBounds} or {@code contains}
 * that might cache data from earlier computations relating to
 * the vertex coordinates.
 * @see java.awt.Polygon#getBounds
 * @since 1.4
 */
 public void invalidate() {
 bounds = null;
 }

 /**
 * Translates the vertices of the {@code Polygon} by
 * {@code deltaX} along the x axis and by
 * {@code deltaY} along the y axis.
 * @param deltaX the amount to translate along the X axis
 * @param deltaY the amount to translate along the Y axis
 * @since 1.1
 */
 public void translate(int deltaX, int deltaY) {
 for (int i = 0; i < npoints; i++) {
 xpoints[i] += deltaX;
 ypoints[i] += deltaY;
 }
 if (bounds != null) {
 bounds.translate(deltaX, deltaY);
 }
 }

 /*
 * Calculates the bounding box of the points passed to the constructor.
 * Sets {@code bounds} to the result.
 * @param xpoints[] array of x coordinates
 * @param ypoints[] array of y coordinates
 * @param npoints the total number of points
 */
 void calculateBounds(int[] xpoints, int[] ypoints, int npoints) {
 int boundsMinX = Integer.MAX_VALUE;
 int boundsMinY = Integer.MAX_VALUE;
 int boundsMaxX = Integer.MIN_VALUE;
 int boundsMaxY = Integer.MIN_VALUE;

 for (int i = 0; i < npoints; i++) {
 int x = xpoints[i];
 boundsMinX = Math.min(boundsMinX, x);
 boundsMaxX = Math.max(boundsMaxX, x);
 int y = ypoints[i];
 boundsMinY = Math.min(boundsMinY, y);
 boundsMaxY = Math.max(boundsMaxY, y);
 }
 bounds = new Rectangle(boundsMinX, boundsMinY,
 boundsMaxX - boundsMinX,
 boundsMaxY - boundsMinY);
 }

 /*
 * Resizes the bounding box to accommodate the specified coordinates.
 * @param x, y the specified coordinates
 */
 void updateBounds(int x, int y) {
 if (x < bounds.x) {
 bounds.width = bounds.width + (bounds.x - x);
 bounds.x = x;
 }
 else {
 bounds.width = Math.max(bounds.width, x - bounds.x);
 // bounds.x = bounds.x;
 }

 if (y < bounds.y) {
 bounds.height = bounds.height + (bounds.y - y);
 bounds.y = y;
 }
 else {
 bounds.height = Math.max(bounds.height, y - bounds.y);
 // bounds.y = bounds.y;
 }
 }

 /**
 * Appends the specified coordinates to this {@code Polygon}.
 * 
 * If an operation that calculates the bounding box of this
 * {@code Polygon} has already been performed, such as
 * {@code getBounds} or {@code contains}, then this
 * method updates the bounding box.
 * @param x the specified X coordinate
 * @param y the specified Y coordinate
 * @see java.awt.Polygon#getBounds
 * @see java.awt.Polygon#contains
 * @since 1.0
 */
 public void addPoint(int x, int y) {
 if (npoints >= xpoints.length || npoints >= ypoints.length) {
 int newLength = npoints * 2;
 // Make sure that newLength will be greater than MIN_LENGTH and
 // aligned to the power of 2
 if (newLength < MIN_LENGTH) {
 newLength = MIN_LENGTH;
 } else if ((newLength & (newLength - 1)) != 0) {
 newLength = Integer.highestOneBit(newLength);
 }

 xpoints = Arrays.copyOf(xpoints, newLength);
 ypoints = Arrays.copyOf(ypoints, newLength);
 }
 xpoints[npoints] = x;
 ypoints[npoints] = y;
 npoints++;
 if (bounds != null) {
 updateBounds(x, y);
 }
 }

 /**
 * Gets the bounding box of this {@code Polygon}.
 * The bounding box is the smallest {@link Rectangle} whose
 * sides are parallel to the x and y axes of the
 * coordinate space, and can completely contain the {@code Polygon}.
 * @return a {@code Rectangle} that defines the bounds of this
 * {@code Polygon}.
 * @since 1.1
 */
 public Rectangle getBounds() {
 return getBoundingBox();
 }

 /**
 * Returns the bounds of this {@code Polygon}.
 * @return the bounds of this {@code Polygon}.
 * @deprecated As of JDK version 1.1,
 * replaced by {@code getBounds()}.
 * @since 1.0
 */
 @Deprecated
 public Rectangle getBoundingBox() {
 if (npoints == 0) {
 return new Rectangle();
 }
 if (bounds == null) {
 calculateBounds(xpoints, ypoints, npoints);
 }
 return bounds.getBounds();
 }

 /**
 * Determines whether the specified {@link Point} is inside this
 * {@code Polygon}.
 * @param p the specified {@code Point} to be tested
 * @return {@code true} if the {@code Polygon} contains the
 * {@code Point}; {@code false} otherwise.
 * @see #contains(double, double)
 * @since 1.0
 */
 public boolean contains(Point p) {
 return contains(p.x, p.y);
 }

 /**
 * Determines whether the specified coordinates are inside this
 * {@code Polygon}.
 *
 * @param x the specified X coordinate to be tested
 * @param y the specified Y coordinate to be tested
 * @return {@code true} if this {@code Polygon} contains
 * the specified coordinates {@code (x,y)};
 * {@code false} otherwise.
 * @see #contains(double, double)
 * @since 1.1
 */
 public boolean contains(int x, int y) {
 return contains((double) x, (double) y);
 }

 /**
 * Determines whether the specified coordinates are contained in this
 * {@code Polygon}.
 * @param x the specified X coordinate to be tested
 * @param y the specified Y coordinate to be tested
 * @return {@code true} if this {@code Polygon} contains
 * the specified coordinates {@code (x,y)};
 * {@code false} otherwise.
 * @see #contains(double, double)
 * @deprecated As of JDK version 1.1,
 * replaced by {@code contains(int, int)}.
 * @since 1.0
 */
 @Deprecated
 public boolean inside(int x, int y) {
 return contains((double) x, (double) y);
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public Rectangle2D getBounds2D() {
 return getBounds();
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean contains(double x, double y) {
 if (npoints <= 2 || !getBoundingBox().contains(x, y)) {
 return false;
 }
 int hits = 0;

 int lastx = xpoints[npoints - 1];
 int lasty = ypoints[npoints - 1];
 int curx, cury;

 // Walk the edges of the polygon
 for (int i = 0; i < npoints; lastx = curx, lasty = cury, i++) {
 curx = xpoints[i];
 cury = ypoints[i];

 if (cury == lasty) {
 continue;
 }

 int leftx;
 if (curx < lastx) {
 if (x >= lastx) {
 continue;
 }
 leftx = curx;
 } else {
 if (x >= curx) {
 continue;
 }
 leftx = lastx;
 }

 double test1, test2;
 if (cury < lasty) {
 if (y < cury || y >= lasty) {
 continue;
 }
 if (x < leftx) {
 hits++;
 continue;
 }
 test1 = x - curx;
 test2 = y - cury;
 } else {
 if (y < lasty || y >= cury) {
 continue;
 }
 if (x < leftx) {
 hits++;
 continue;
 }
 test1 = x - lastx;
 test2 = y - lasty;
 }

 if (test1 < (test2 / (lasty - cury) * (lastx - curx))) {
 hits++;
 }
 }

 return ((hits & 1) != 0);
 }

 private Crossings getCrossings(double xlo, double ylo,
 double xhi, double yhi)
 {
 Crossings cross = new Crossings.EvenOdd(xlo, ylo, xhi, yhi);
 int lastx = xpoints[npoints - 1];
 int lasty = ypoints[npoints - 1];
 int curx, cury;

 // Walk the edges of the polygon
 for (int i = 0; i < npoints; i++) {
 curx = xpoints[i];
 cury = ypoints[i];
 if (cross.accumulateLine(lastx, lasty, curx, cury)) {
 return null;
 }
 lastx = curx;
 lasty = cury;
 }

 return cross;
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean contains(Point2D p) {
 return contains(p.getX(), p.getY());
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean intersects(double x, double y, double w, double h) {
 if (npoints <= 0 || !getBoundingBox().intersects(x, y, w, h)) {
 return false;
 }

 Crossings cross = getCrossings(x, y, x+w, y+h);
 return (cross == null || !cross.isEmpty());
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean intersects(Rectangle2D r) {
 return intersects(r.getX(), r.getY(), r.getWidth(), r.getHeight());
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean contains(double x, double y, double w, double h) {
 if (npoints <= 0 || !getBoundingBox().intersects(x, y, w, h)) {
 return false;
 }

 Crossings cross = getCrossings(x, y, x+w, y+h);
 return (cross != null && cross.covers(y, y+h));
 }

 /**
 * {@inheritDoc}
 * @since 1.2
 */
 public boolean contains(Rectangle2D r) {
 return contains(r.getX(), r.getY(), r.getWidth(), r.getHeight());
 }

 /**
 * Returns an iterator object that iterates along the boundary of this
 * {@code Polygon} and provides access to the geometry
 * of the outline of this {@code Polygon}. An optional
 * {@link AffineTransform} can be specified so that the coordinates
 * returned in the iteration are transformed accordingly.
 * @param at an optional {@code AffineTransform} to be applied to the
 * coordinates as they are returned in the iteration, or
 * {@code null} if untransformed coordinates are desired
 * @return a {@link PathIterator} object that provides access to the
 * geometry of this {@code Polygon}.
 * @since 1.2
 */
 public PathIterator getPathIterator(AffineTransform at) {
 return new PolygonPathIterator(this, at);
 }

 /**
 * Returns an iterator object that iterates along the boundary of
 * the {@code Shape} and provides access to the geometry of the
 * outline of the {@code Shape}. Only SEG_MOVETO, SEG_LINETO, and
 * SEG_CLOSE point types are returned by the iterator.
 * Since polygons are already flat, the {@code flatness} parameter
 * is ignored. An optional {@code AffineTransform} can be specified
 * in which case the coordinates returned in the iteration are transformed
 * accordingly.
 * @param at an optional {@code AffineTransform} to be applied to the
 * coordinates as they are returned in the iteration, or
 * {@code null} if untransformed coordinates are desired
 * @param flatness the maximum amount that the control points
 * for a given curve can vary from collinear before a subdivided
 * curve is replaced by a straight line connecting the
 * endpoints. Since polygons are already flat the
 * {@code flatness} parameter is ignored.
 * @return a {@code PathIterator} object that provides access to the
 * {@code Shape} object's geometry.
 * @since 1.2
 */
 public PathIterator getPathIterator(AffineTransform at, double flatness) {
 return getPathIterator(at);
 }

 static class PolygonPathIterator implements PathIterator {
 Polygon poly;
 AffineTransform transform;
 int index;

 public PolygonPathIterator(Polygon pg, AffineTransform at) {
 poly = pg;
 transform = at;
 if (pg.npoints == 0) {
 // Prevent a spurious SEG_CLOSE segment
 index = 1;
 }
 }

 /**
 * Returns the winding rule for determining the interior of the
 * path.
 * @return an integer representing the current winding rule.
 * @see PathIterator#WIND_NON_ZERO
 */
 public int getWindingRule() {
 return WIND_EVEN_ODD;
 }

 /**
 * Tests if there are more points to read.
 * @return {@code true} if there are more points to read;
 * {@code false} otherwise.
 */
 public boolean isDone() {
 return index > poly.npoints;
 }

 /**
 * Moves the iterator forwards, along the primary direction of
 * traversal, to the next segment of the path when there are
 * more points in that direction.
 */
 public void next() {
 index++;
 }

 /**
 * 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, or SEG_CLOSE.
 * A {@code float} array of length 2 must be passed in and
 * can be used to store the coordinates of the point(s).
 * Each point is stored as a pair of {@code float} x, y
 * coordinates. SEG_MOVETO and SEG_LINETO types return one
 * point, and SEG_CLOSE does not return any points.
 * @param coords a {@code float} array that specifies the
 * coordinates of the point(s)
 * @return an integer representing the type and coordinates of the
 * current path segment.
 * @see PathIterator#SEG_MOVETO
 * @see PathIterator#SEG_LINETO
 * @see PathIterator#SEG_CLOSE
 */
 public int currentSegment(float[] coords) {
 if (index >= poly.npoints) {
 return SEG_CLOSE;
 }
 coords[0] = poly.xpoints[index];
 coords[1] = poly.ypoints[index];
 if (transform != null) {
 transform.transform(coords, 0, coords, 0, 1);
 }
 return (index == 0 ? SEG_MOVETO : SEG_LINETO);
 }

 /**
 * 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, or SEG_CLOSE.
 * A {@code double} array of length 2 must be passed in and
 * can be used to store the coordinates of the point(s).
 * Each point is stored as a pair of {@code double} x, y
 * coordinates.
 * SEG_MOVETO and SEG_LINETO types return one point,
 * and SEG_CLOSE does not return any points.
 * @param coords a {@code double} array that specifies the
 * coordinates of the point(s)
 * @return an integer representing the type and coordinates of the
 * current path segment.
 * @see PathIterator#SEG_MOVETO
 * @see PathIterator#SEG_LINETO
 * @see PathIterator#SEG_CLOSE
 */
 public int currentSegment(double[] coords) {
 if (index >= poly.npoints) {
 return SEG_CLOSE;
 }
 coords[0] = poly.xpoints[index];
 coords[1] = poly.ypoints[index];
 if (transform != null) {
 transform.transform(coords, 0, coords, 0, 1);
 }
 return (index == 0 ? SEG_MOVETO : SEG_LINETO);
 }
 }
}

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