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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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package com.sun.javafx.geom;

import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.Vector;
import com.sun.javafx.geom.transform.BaseTransform;


/**
 * An Area object stores and manipulates a
 * resolution-independent description of an enclosed area of
 * 2-dimensional space.
 * Area objects can be transformed and can perform
 * various Constructive Area Geometry (CAG) operations when combined
 * with other Area objects.
 * The CAG operations include area
 * {@link #add addition}, {@link #subtract subtraction},
 * {@link #intersect intersection}, and {@link #exclusiveOr exclusive or}.
 * See the linked method documentation for examples of the various
 * operations.
 * 

* The Area class implements the Shape * interface and provides full support for all of its hit-testing * and path iteration facilities, but an Area is more * specific than a generalized path in a number of ways: *

    *
  • Only closed paths and sub-paths are stored. * Area objects constructed from unclosed paths * are implicitly closed during construction as if those paths * had been filled by the Graphics2D.fill method. *
  • The interiors of the individual stored sub-paths are all * non-empty and non-overlapping. Paths are decomposed during * construction into separate component non-overlapping parts, * empty pieces of the path are discarded, and then these * non-empty and non-overlapping properties are maintained * through all subsequent CAG operations. Outlines of different * component sub-paths may touch each other, as long as they * do not cross so that their enclosed areas overlap. *
  • The geometry of the path describing the outline of the * Area resembles the path from which it was * constructed only in that it describes the same enclosed * 2-dimensional area, but may use entirely different types * and ordering of the path segments to do so. *
* Interesting issues which are not always obvious when using * the Area include: *
    *
  • Creating an Area from an unclosed (open) * Shape results in a closed outline in the * Area object. *
  • Creating an Area from a Shape * which encloses no area (even when "closed") produces an * empty Area. A common example of this issue * is that producing an Area from a line will * be empty since the line encloses no area. An empty * Area will iterate no geometry in its * PathIterator objects. *
  • A self-intersecting Shape may be split into * two (or more) sub-paths each enclosing one of the * non-intersecting portions of the original path. *
  • An Area may take more path segments to * describe the same geometry even when the original * outline is simple and obvious. The analysis that the * Area class must perform on the path may * not reflect the same concepts of "simple and obvious" * as a human being perceives. *
*/ public class Area extends Shape { private static final Vector EmptyCurves = new Vector(); private Vector curves; /** * Default constructor which creates an empty area. */ public Area() { curves = EmptyCurves; } /** * The Area class creates an area geometry from the * specified {@link Shape} object. The geometry is explicitly * closed, if the Shape is not already closed. The * fill rule (even-odd or winding) specified by the geometry of the * Shape is used to determine the resulting enclosed area. * @param s the Shape from which the area is constructed * @throws NullPointerException if s is null */ public Area(Shape s) { if (s instanceof Area) { curves = ((Area) s).curves; } else { curves = pathToCurves(s.getPathIterator(null)); } } public Area(PathIterator iter) { curves = pathToCurves(iter); } private static Vector pathToCurves(PathIterator pi) { Vector curves = new Vector(); int windingRule = pi.getWindingRule(); // coords array is big enough for holding: // coordinates returned from currentSegment (6) // OR // two subdivided quadratic curves (2+4+4=10) // AND // 0-1 horizontal splitting parameters // OR // 2 parametric equation derivative coefficients // OR // three subdivided cubic curves (2+6+6+6=20) // AND // 0-2 horizontal splitting parameters // OR // 3 parametric equation derivative coefficients float coords[] = new float[6]; double tmp[] = new double[23]; double movx = 0, movy = 0; double curx = 0, cury = 0; double newx, newy; while (!pi.isDone()) { switch (pi.currentSegment(coords)) { case PathIterator.SEG_MOVETO: Curve.insertLine(curves, curx, cury, movx, movy); curx = movx = coords[0]; cury = movy = coords[1]; Curve.insertMove(curves, movx, movy); break; case PathIterator.SEG_LINETO: newx = coords[0]; newy = coords[1]; Curve.insertLine(curves, curx, cury, newx, newy); curx = newx; cury = newy; break; case PathIterator.SEG_QUADTO: newx = coords[2]; newy = coords[3]; Curve.insertQuad(curves, tmp, curx, cury, coords[0], coords[1], coords[2], coords[3]); curx = newx; cury = newy; break; case PathIterator.SEG_CUBICTO: newx = coords[4]; newy = coords[5]; Curve.insertCubic(curves, tmp, curx, cury, coords[0], coords[1], coords[2], coords[3], coords[4], coords[5]); curx = newx; cury = newy; break; case PathIterator.SEG_CLOSE: Curve.insertLine(curves, curx, cury, movx, movy); curx = movx; cury = movy; break; } pi.next(); } Curve.insertLine(curves, curx, cury, movx, movy); AreaOp operator; if (windingRule == PathIterator.WIND_EVEN_ODD) { operator = new AreaOp.EOWindOp(); } else { operator = new AreaOp.NZWindOp(); } return operator.calculate(curves, EmptyCurves); } /** * Adds the shape of the specified Area to the * shape of this Area. * The resulting shape of this Area will include * the union of both shapes, or all areas that were contained * in either this or the specified Area. *
     *     // Example:
     *     Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]);
     *     Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]);
     *     a1.add(a2);
     *
     *        a1(before)     +         a2         =     a1(after)
     *
     *     ################     ################     ################
     *     ##############         ##############     ################
     *     ############             ############     ################
     *     ##########                 ##########     ################
     *     ########                     ########     ################
     *     ######                         ######     ######    ######
     *     ####                             ####     ####        ####
     *     ##                                 ##     ##            ##
     * 
* @param rhs the Area to be added to the * current shape * @throws NullPointerException if rhs is null */ public void add(Area rhs) { curves = new AreaOp.AddOp().calculate(this.curves, rhs.curves); invalidateBounds(); } /** * Subtracts the shape of the specified Area from the * shape of this Area. * The resulting shape of this Area will include * areas that were contained only in this Area * and not in the specified Area. *
     *     // Example:
     *     Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]);
     *     Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]);
     *     a1.subtract(a2);
     *
     *        a1(before)     -         a2         =     a1(after)
     *
     *     ################     ################
     *     ##############         ##############     ##
     *     ############             ############     ####
     *     ##########                 ##########     ######
     *     ########                     ########     ########
     *     ######                         ######     ######
     *     ####                             ####     ####
     *     ##                                 ##     ##
     * 
* @param rhs the Area to be subtracted from the * current shape * @throws NullPointerException if rhs is null */ public void subtract(Area rhs) { curves = new AreaOp.SubOp().calculate(this.curves, rhs.curves); invalidateBounds(); } /** * Sets the shape of this Area to the intersection of * its current shape and the shape of the specified Area. * The resulting shape of this Area will include * only areas that were contained in both this Area * and also in the specified Area. *
     *     // Example:
     *     Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]);
     *     Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]);
     *     a1.intersect(a2);
     *
     *      a1(before)   intersect     a2         =     a1(after)
     *
     *     ################     ################     ################
     *     ##############         ##############       ############
     *     ############             ############         ########
     *     ##########                 ##########           ####
     *     ########                     ########
     *     ######                         ######
     *     ####                             ####
     *     ##                                 ##
     * 
* @param rhs the Area to be intersected with this * Area * @throws NullPointerException if rhs is null */ public void intersect(Area rhs) { curves = new AreaOp.IntOp().calculate(this.curves, rhs.curves); invalidateBounds(); } /** * Sets the shape of this Area to be the combined area * of its current shape and the shape of the specified Area, * minus their intersection. * The resulting shape of this Area will include * only areas that were contained in either this Area * or in the specified Area, but not in both. *
     *     // Example:
     *     Area a1 = new Area([triangle 0,0 => 8,0 => 0,8]);
     *     Area a2 = new Area([triangle 0,0 => 8,0 => 8,8]);
     *     a1.exclusiveOr(a2);
     *
     *        a1(before)    xor        a2         =     a1(after)
     *
     *     ################     ################
     *     ##############         ##############     ##            ##
     *     ############             ############     ####        ####
     *     ##########                 ##########     ######    ######
     *     ########                     ########     ################
     *     ######                         ######     ######    ######
     *     ####                             ####     ####        ####
     *     ##                                 ##     ##            ##
     * 
* @param rhs the Area to be exclusive ORed with this * Area. * @throws NullPointerException if rhs is null */ public void exclusiveOr(Area rhs) { curves = new AreaOp.XorOp().calculate(this.curves, rhs.curves); invalidateBounds(); } /** * Removes all of the geometry from this Area and * restores it to an empty area. */ public void reset() { curves = new Vector(); invalidateBounds(); } /** * Tests whether this Area object encloses any area. * @return true if this Area object * represents an empty area; false otherwise. */ public boolean isEmpty() { return (curves.size() == 0); } /** * Tests whether this Area consists entirely of * straight edged polygonal geometry. * @return true if the geometry of this * Area consists entirely of line segments; * false otherwise. */ public boolean isPolygonal() { Enumeration enum_ = curves.elements(); while (enum_.hasMoreElements()) { if (((Curve) enum_.nextElement()).getOrder() > 1) { return false; } } return true; } /** * Tests whether this Area is rectangular in shape. * @return true if the geometry of this * Area is rectangular in shape; false * otherwise. */ public boolean isRectangular() { int size = curves.size(); if (size == 0) { return true; } if (size > 3) { return false; } Curve c1 = (Curve) curves.get(1); Curve c2 = (Curve) curves.get(2); if (c1.getOrder() != 1 || c2.getOrder() != 1) { return false; } if (c1.getXTop() != c1.getXBot() || c2.getXTop() != c2.getXBot()) { return false; } if (c1.getYTop() != c2.getYTop() || c1.getYBot() != c2.getYBot()) { // One might be able to prove that this is impossible... return false; } return true; } /** * Tests whether this Area is comprised of a single * closed subpath. This method returns true if the * path contains 0 or 1 subpaths, or false if the path * contains more than 1 subpath. The subpaths are counted by the * number of {@link PathIterator#SEG_MOVETO SEG_MOVETO} segments * that appear in the path. * @return true if the Area is comprised * of a single basic geometry; false otherwise. */ public boolean isSingular() { if (curves.size() < 3) { return true; } Enumeration enum_ = curves.elements(); enum_.nextElement(); // First Order0 "moveto" while (enum_.hasMoreElements()) { if (((Curve) enum_.nextElement()).getOrder() == 0) { return false; } } return true; } private RectBounds cachedBounds; private void invalidateBounds() { cachedBounds = null; } private RectBounds getCachedBounds() { if (cachedBounds != null) { return cachedBounds; } RectBounds r = new RectBounds(); if (curves.size() > 0) { Curve c = (Curve) curves.get(0); // First point is always an order 0 curve (moveto) r.setBounds((float) c.getX0(), (float) c.getY0(), 0, 0); for (int i = 1; i < curves.size(); i++) { ((Curve) curves.get(i)).enlarge(r); } } return (cachedBounds = r); } /** * Returns a high precision bounding {@link RectBounds} that * completely encloses this Area. *

* The Area class will attempt to return the tightest bounding * box possible for the Shape. The bounding box will not be * padded to include the control points of curves in the outline * of the Shape, but should tightly fit the actual geometry of * the outline itself. * @return the bounding RectBounds for the * Area. */ public RectBounds getBounds() { return new RectBounds(getCachedBounds()); } /** * Tests whether the geometries of the two Area objects * cover the same area. * This method will return false if the argument is null. * @param other the Area to be compared to this * Area * @return true if the two geometries are equivalent; * false otherwise. */ public boolean isEquivalent(Area other) { // REMIND: A *much* simpler operation should be possible... // Should be able to do a curve-wise comparison since all Areas // should evaluate their curves in the same top-down order. if (other == this) { return true; } if (other == null) { return false; } Vector c = new AreaOp.XorOp().calculate(this.curves, other.curves); return c.isEmpty(); } /** * Transforms the geometry of this Area using the specified * {@link BaseTransform}. The geometry is transformed in place, which * permanently changes the enclosed area defined by this object. * @param tx the transformation used to transform the area * @throws NullPointerException if t is null */ public void transform(BaseTransform tx) { if (tx == null) { throw new NullPointerException("transform must not be null"); } // REMIND: A simpler operation can be performed for some types // of transform. curves = pathToCurves(getPathIterator(tx)); invalidateBounds(); } /** * Creates a new Area object that contains the same * geometry as this Area transformed by the specified * BaseTransform. This Area object * is unchanged. * @param tx the specified BaseTransform used to transform * the new Area * @throws NullPointerException if t is null * @return a new Area object representing the transformed * geometry. */ public Area createTransformedArea(BaseTransform tx) { Area a = new Area(this); a.transform(tx); return a; } /** * {@inheritDoc} */ public boolean contains(float x, float y) { if (!getCachedBounds().contains(x, y)) { return false; } Enumeration enum_ = curves.elements(); int crossings = 0; while (enum_.hasMoreElements()) { Curve c = (Curve) enum_.nextElement(); crossings += c.crossingsFor(x, y); } return ((crossings & 1) == 1); } /** * {@inheritDoc} */ @Override public boolean contains(Point2D p) { return contains(p.x, p.y); } /** * {@inheritDoc} */ public boolean contains(float x, float y, float w, float h) { if (w < 0 || h < 0) { return false; } if (!getCachedBounds().contains(x, y) || !getCachedBounds().contains(x+w, y+h)) { return false; } Crossings c = Crossings.findCrossings(curves, x, y, x+w, y+h); return (c != null && c.covers(y, y+h)); } /** * {@inheritDoc} */ public boolean intersects(float x, float y, float w, float h) { if (w < 0 || h < 0) { return false; } if (!getCachedBounds().intersects(x, y, w, h)) { return false; } Crossings c = Crossings.findCrossings(curves, x, y, x+w, y+h); return (c == null || !c.isEmpty()); } /** * Creates a {@link PathIterator} for the outline of this * Area object. This Area object is unchanged. * @param tx an optional BaseTransform to be applied to * the coordinates as they are returned in the iteration, or * null if untransformed coordinates are desired * @return the PathIterator object that returns the * geometry of the outline of this Area, one * segment at a time. */ public PathIterator getPathIterator(BaseTransform tx) { return new AreaIterator(curves, tx); } /** * Creates a PathIterator for the flattened outline of * this Area object. Only uncurved path segments * represented by the SEG_MOVETO, SEG_LINETO, and SEG_CLOSE point * types are returned by the iterator. This Area * object is unchanged. * @param tx an optional BaseTransform to be * applied to the coordinates as they are returned in the * iteration, or null if untransformed coordinates * are desired * @param flatness the maximum amount that the control points * for a given curve can vary from colinear before a subdivided * curve is replaced by a straight line connecting the end points * @return the PathIterator object that returns the * geometry of the outline of this Area, one segment * at a time. */ public PathIterator getPathIterator(BaseTransform tx, float flatness) { return new FlatteningPathIterator(getPathIterator(tx), flatness); } @Override public Area copy() { return new Area(this); } } class AreaIterator implements PathIterator { private BaseTransform transform; private Vector curves; private int index; private Curve prevcurve; private Curve thiscurve; public AreaIterator(Vector curves, BaseTransform tx) { this.curves = curves; this.transform = tx; if (curves.size() >= 1) { thiscurve = (Curve) curves.get(0); } } public int getWindingRule() { // REMIND: Which is better, EVEN_ODD or NON_ZERO? // The paths calculated could be classified either way. //return WIND_EVEN_ODD; return WIND_NON_ZERO; } public boolean isDone() { return (prevcurve == null && thiscurve == null); } public void next() { if (prevcurve != null) { prevcurve = null; } else { prevcurve = thiscurve; index++; if (index < curves.size()) { thiscurve = (Curve) curves.get(index); if (thiscurve.getOrder() != 0 && prevcurve.getX1() == thiscurve.getX0() && prevcurve.getY1() == thiscurve.getY0()) { prevcurve = null; } } else { thiscurve = null; } } } public int currentSegment(float coords[]) { int segtype; int numpoints; if (prevcurve != null) { // Need to finish off junction between curves if (thiscurve == null || thiscurve.getOrder() == 0) { return SEG_CLOSE; } coords[0] = (float) thiscurve.getX0(); coords[1] = (float) thiscurve.getY0(); segtype = SEG_LINETO; numpoints = 1; } else if (thiscurve == null) { throw new NoSuchElementException("area iterator out of bounds"); } else { segtype = thiscurve.getSegment(coords); numpoints = thiscurve.getOrder(); if (numpoints == 0) { numpoints = 1; } } if (transform != null) { transform.transform(coords, 0, coords, 0, numpoints); } return segtype; } }





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