gcc/libjava/java/awt/Polygon.java

423 lines
11 KiB
Java
Raw Normal View History

/* Copyright (C) 2001 Free Software Foundation
This file is part of libjava.
This software is copyrighted work licensed under the terms of the
Libjava License. Please consult the file "LIBJAVA_LICENSE" for
details. */
package java.awt;
import java.awt.geom.*;
import java.io.Serializable;
import java.util.Arrays;
/**
* @author Tom Tromey <tromey@redhat.com>
* @date May 10, 2001
*/
/** The Polygon class represents a closed region whose boundary is
made of line segments. The Polygon is defined by its vertices. */
public class Polygon implements Shape, Serializable
{
/** The bounds of the polygon. This is null until the bounds have
* been computed for the first time; then it is correctly
* maintained whenever it is modified. */
protected Rectangle bounds;
/** The number of points in the polygon. */
public int npoints;
/** The x coordinates of the points. */
public int[] xpoints;
/** The y coordinates of the points. */
public int[] ypoints;
/** Create a new, empty Polygon. */
public Polygon ()
{
this.xpoints = new int[0];
this.ypoints = new int[0];
this.npoints = 0;
}
/** Create a new Polygon from the given vertices.
* @param xpoints The x coordinates
* @param ypoints The y coordinates
* @param npoints The number of points
*/
public Polygon (int[] xpoints, int[] ypoints, int npoints)
{
// We make explicit copies instead of relying on clone so that we
// ensure the new arrays are the same size.
this.xpoints = new int[npoints];
this.ypoints = new int[npoints];
System.arraycopy (xpoints, 0, this.xpoints, 0, npoints);
System.arraycopy (ypoints, 0, this.ypoints, 0, npoints);
}
/** Append the specified point to this Polygon.
* @param x The x coordinate
* @param y The y coordinate
*/
public void addPoint (int x, int y)
{
int[] newx = new int[npoints + 1];
System.arraycopy (xpoints, 0, newx, 0, npoints);
int[] newy = new int[npoints + 1];
System.arraycopy (ypoints, 0, newy, 0, npoints);
newx[npoints] = x;
newy[npoints] = y;
++npoints;
xpoints = newx;
ypoints = newy;
// It is simpler to just recompute.
if (bounds != null)
computeBoundingBox ();
}
/** Return true if the indicated point is inside this Polygon.
* This uses an even-odd rule to determine insideness.
* @param x The x coordinate
* @param y The y coordinate
* @returns true if the point is contained by this Polygon.
*/
public boolean contains (double x, double y)
{
// What we do is look at each line segment. If the line segment
// crosses the "scan line" at y at a point x' < x, then we
// increment our counter. At the end, an even number means the
// point is outside the polygon. Instead of a number, though, we
// use a boolean.
boolean inside = false;
for (int i = 0; i < npoints; ++i)
{
// Handle the wrap case.
int x2 = (i == npoints) ? xpoints[0] : xpoints[i + 1];
int y2 = (i == npoints) ? ypoints[0] : ypoints[i + 1];
if (ypoints[i] == y2)
{
// We ignore horizontal lines. This might give weird
// results in some situations -- ?
continue;
}
double t = (y - ypoints[i]) / (double) (y2 - ypoints[i]);
double x3 = xpoints[i] + t * (x2 - xpoints[i]);
if (x3 < x)
inside = ! inside;
}
return inside;
}
/** Return true if the indicated rectangle is entirely inside this
* Polygon.
* This uses an even-odd rule to determine insideness.
* @param x The x coordinate
* @param y The y coordinate
* @param w The width
* @param h The height
* @returns true if the rectangle is contained by this Polygon.
*/
public boolean contains (double x, double y, double w, double h)
{
return intersectOrContains (x, y, w, h, false);
}
/** Return true if the indicated point is inside this Polygon.
* This uses an even-odd rule to determine insideness.
* @param x The x coordinate
* @param y The y coordinate
* @returns true if the point is contained by this Polygon.
*/
public boolean contains (int x, int y)
{
return contains ((double) x, (double) y);
}
/** Return true if the indicated point is inside this Polygon.
* This uses an even-odd rule to determine insideness.
* @param p The point
* @returns true if the point is contained by this Polygon.
*/
public boolean contains (Point p)
{
return contains (p.x, p.y);
}
/** Return true if the indicated point is inside this Polygon.
* This uses an even-odd rule to determine insideness.
* @param p The point
* @returns true if the point is contained by this Polygon.
*/
public boolean contains (Point2D p)
{
return contains (p.getX (), p.getY ());
}
/** Return true if the indicated rectangle is entirely inside this
* Polygon. This uses an even-odd rule to determine insideness.
* @param r The rectangle
* @returns true if the rectangle is contained by this Polygon.
*/
public boolean contains (Rectangle2D r)
{
return contains (r.getX (), r.getY (), r.getWidth (), r.getHeight ());
}
/** Returns the bounds of this Polygon.
* @deprecated Use getBounds() instead.
*/
public Rectangle getBoundingBox ()
{
if (bounds == null)
computeBoundingBox ();
return bounds;
}
/** Returns the bounds of this Polygon. */
public Rectangle getBounds ()
{
if (bounds == null)
computeBoundingBox ();
return bounds;
}
/** Returns the bounds of this Polygon. */
public Rectangle2D getBounds2D ()
{
if (bounds == null)
computeBoundingBox ();
return bounds; // Why not?
}
/** Return an iterator for the boundary of this Polygon.
* @param at A transform to apply to the coordinates.
* @returns A path iterator for the Polygon's boundary.
*/
public PathIterator getPathIterator (AffineTransform at)
{
return new Iterator (at);
}
/** Return an iterator for the boundary of this Polygon.
* @param at A transform to apply to the coordinates.
* @param flatness The flatness of the result; it is ignored by
* this class.
* @returns A path iterator for the Polygon's boundary.
*/
public PathIterator getPathIterator (AffineTransform at, double flatness)
{
// We ignore the flatness.
return new Iterator (at);
}
/** @deprecated use contains(int,int). */
public boolean inside (int x, int y)
{
return contains (x, y);
}
/** Return true if this Polygon's interior intersects the given
* rectangle's interior.
* @param x The x coordinate
* @param y The y coordinate
* @param w The width
* @param h The height
*/
public boolean intersects (double x, double y, double w, double h)
{
return intersectOrContains (x, y, w, h, true);
}
/** Return true if this Polygon's interior intersects the given
* rectangle's interior.
* @param r The rectangle
*/
public boolean intersects (Rectangle2D r)
{
return intersects (r.getX (), r.getY (), r.getWidth (), r.getHeight ());
}
// This tests for intersection with or containment of a rectangle,
// depending on the INTERSECT argument.
private boolean intersectOrContains (double x, double y, double w, double h,
boolean intersect)
{
// First compute the rectangle of possible intersection points.
Rectangle r = getBounds ();
int minx = Math.max (r.x, (int) x);
int maxx = Math.min (r.x + r.width, (int) (x + w));
int miny = Math.max (r.y, (int) y);
int maxy = Math.min (r.y + r.height, (int) (y + h));
if (miny > maxy)
return false;
double[] crosses = new double[npoints + 1];
for (; miny < maxy; ++miny)
{
// First compute every place where the polygon might intersect
// the scan line at Y.
int ins = 0;
for (int i = 0; i < npoints; ++i)
{
// Handle the wrap case.
int x2 = (i == npoints) ? xpoints[0] : xpoints[i + 1];
int y2 = (i == npoints) ? ypoints[0] : ypoints[i + 1];
if (ypoints[i] == y2)
{
// We ignore horizontal lines. This might give weird
// results in some situations -- ?
continue;
}
double t = (((double) miny - ypoints[i])
/ (double) (y2 - ypoints[i]));
double x3 = xpoints[i] + t * (x2 - xpoints[i]);
crosses[ins++] = x3;
}
// Now we can sort into increasing order and look to see if
// any point in the rectangle is in the polygon. We examine
// every other pair due to our even-odd rule.
Arrays.sort (crosses, 0, ins);
int i = intersect ? 0 : 1;
for (; i < ins - 1; i += 2)
{
// Pathological case.
if (crosses[i] == crosses[i + 1])
continue;
// Found a point on the inside.
if ((crosses[i] >= x && crosses[i] < x + w)
|| (crosses[i + 1] >= x && crosses[i + 1] < x + w))
{
// If we're checking containment then we just lost.
// But if we're checking intersection then we just
// won.
return intersect;
}
}
}
return false;
}
/** Translates all the vertices of the polygon via a given vector.
* @param deltaX The X offset
* @param deltaY The Y offset
*/
public void translate (int deltaX, int deltaY)
{
for (int i = 0; i < npoints; ++i)
{
xpoints[i] += deltaX;
ypoints[i] += deltaY;
}
if (bounds != null)
{
bounds.x += deltaX;
bounds.y += deltaY;
}
}
// This computes the bounding box if required.
private void computeBoundingBox ()
{
if (npoints == 0)
{
// This is wrong if the user adds a new point, but we
// account for that in addPoint().
bounds = new Rectangle (0, 0, 0, 0);
}
else
{
int maxx = xpoints[0];
int minx = xpoints[0];
int maxy = ypoints[0];
int miny = ypoints[0];
for (int i = 1; i < npoints; ++i)
{
maxx = Math.max (maxx, xpoints[i]);
minx = Math.min (minx, xpoints[i]);
maxy = Math.max (maxy, ypoints[i]);
miny = Math.min (miny, ypoints[i]);
}
bounds = new Rectangle (minx, miny, maxx - minx, maxy - miny);
}
}
private class Iterator implements PathIterator
{
public AffineTransform xform;
public int where;
public Iterator (AffineTransform xform)
{
this.xform = xform;
where = 0;
}
public int currentSegment (double[] coords)
{
int r;
if (where < npoints)
{
coords[0] = xpoints[where];
coords[1] = ypoints[where];
r = (where == 0) ? SEG_MOVETO : SEG_LINETO;
xform.transform (coords, 0, coords, 0, 1);
++where;
}
else
r = SEG_CLOSE;
return r;
}
public int currentSegment (float[] coords)
{
int r;
if (where < npoints)
{
coords[0] = xpoints[where];
coords[1] = ypoints[where];
r = (where == 0) ? SEG_MOVETO : SEG_LINETO;
xform.transform (coords, 0, coords, 0, 1);
}
else
r = SEG_CLOSE;
return r;
}
public int getWindingRule ()
{
return WIND_EVEN_ODD;
}
public boolean isDone ()
{
return where == npoints + 1;
}
public void next ()
{
++where;
}
}
}