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+/* PolyEdge.java -- An edge in a polygon, used for polygon filling
+ Copyright (C) 2006 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package gnu.java.awt.java2d;
+
+import gnu.java.math.Fixed;
+
+/**
+ * An edge in a polygon.
+ *
+ * @author Roman Kennke (kennke@aicas.com)
+ */
+final class PolyEdge
+ implements Comparable
+{
+
+ /**
+ * The start and end coordinates of the edge. y0 is always smaller or equal
+ * than y1.
+ *
+ * These values are stored as fixed-point decimals.
+ */
+ public int x0, y0, x1, y1;
+
+ /**
+ * The slope of the edge. This is dx / dy.
+ *
+ * This is a fixed point decimal.
+ */
+ private int slope;
+
+ /**
+ * The intersection of this edge with the current scanline.
+ *
+ * This is a fixed point decimal.
+ */
+ int xIntersection;
+
+ /**
+ * Indicates whether this edge is from the clip or from the target shape.
+ */
+ boolean isClip;
+
+ /**
+ * Implements a linked list for the edge pool.
+ */
+ PolyEdge poolNext;
+
+ /**
+ * Implements a linked list for the scanline edge lists.
+ */
+ PolyEdge scanlineNext;
+
+ /**
+ * Create an uninitialized edge.
+ */
+ PolyEdge()
+ {
+ // Nothing to do here.
+ }
+
+ /**
+ * Creates a new PolyEdge with the specified coordinates.
+ *
+ * @param x0 the starting point, x coordinate
+ * @param y0 the starting point, y coordinate
+ * @param x1 the end point, x coordinate
+ * @param y1 the end point, y coordinate
+ */
+ PolyEdge(int n, int x0, int y0, int x1, int y1, boolean clip)
+ {
+ init(n, x0, y0, x1, y1, clip);
+ }
+
+ /**
+ * (Re-) Initializes this edge.
+ *
+ * @param x0
+ * @param y0
+ * @param x1
+ * @param y1
+ */
+ void init(int n, int x0, int y0, int x1, int y1, boolean clip)
+ {
+ isClip = clip;
+ if (y0 < y1)
+ {
+ this.x0 = x0;
+ this.y0 = y0;
+ this.x1 = x1;
+ this.y1 = y1;
+ }
+ else
+ {
+ this.x0 = x1;
+ this.y0 = y1;
+ this.x1 = x0;
+ this.y1 = y0;
+ }
+ slope = Fixed.div(n, this.x1 - this.x0, this.y1 - this.y0);
+ }
+
+ /**
+ * Sorts PolyEdges by the x coordinate from the minimum x value.
+ */
+ public int compareTo(Object o)
+ {
+ PolyEdge other = (PolyEdge) o;
+ int comp = 0;
+ if (x0 < other.x0)
+ comp = -1;
+ else if (x0 > other.x0)
+ comp = 1;
+ return comp;
+ }
+
+ /**
+ * Intersects this edge with the scanline at height y. The result is
+ * stored in {@link #xIntersection}.
+ *
+ * @param y the scanline
+ */
+ void intersect(int n, int y)
+ {
+ int dy = y - y0;
+ int dx = Fixed.mul(n, slope, dy);
+ xIntersection = x0 + dx;
+ }
+
+ public String toString()
+ {
+ return "Edge: " + x0 + ", " + y0 + ", " + x1 + ", " + y1 + ", slope: "
+ + slope + ", xIntersection: " + xIntersection
+ + ", isClip: " + isClip;
+ }
+}