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Diffstat (limited to 'libjava/classpath/gnu/java/awt/java2d/ActiveEdges.java')
| -rw-r--r-- | libjava/classpath/gnu/java/awt/java2d/ActiveEdges.java | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/awt/java2d/ActiveEdges.java b/libjava/classpath/gnu/java/awt/java2d/ActiveEdges.java new file mode 100644 index 000000000..efe1966e3 --- /dev/null +++ b/libjava/classpath/gnu/java/awt/java2d/ActiveEdges.java @@ -0,0 +1,197 @@ +/* ActiveEdges.java -- A collection of active edges for scanline conversion + 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.lang.CPStringBuilder; + +/** + * A collection of active edges for scanline conversion. + */ +final class ActiveEdges +{ + + /** + * The active edges. This can contain null values at arbirary locations. + * The method #sort() packs this together. + */ + private PolyEdge[] activeEdges; + + /** + * The actual number of active edges. The array can be bigger than this + * number. + */ + private int numActiveEdges; + + /** + * Creates a new ActiveEdges object. + */ + ActiveEdges() + { + activeEdges = new PolyEdge[8]; + numActiveEdges = 0; + } + + /** + * Clears out all active edges. This is cheap as it simply resets the + * counter to 0. It does not release all references to PolyEdge instances. + */ + void clear() + { + numActiveEdges = 0; + } + + /** + * Adds the specified edge to the list of active edges. This does not yet + * sort the edges and therefore does destroy any order of the list. + * + * @param edge the edge to add + */ + void add(PolyEdge edge) + { + // Grow array when necessary. + int oldSize = activeEdges.length; + if (numActiveEdges >= oldSize) + { + int newSize = oldSize + oldSize / 4 + 1; + PolyEdge[] newEdges = new PolyEdge[newSize]; + System.arraycopy(activeEdges, 0, newEdges, 0, oldSize); + activeEdges = newEdges; + } + activeEdges[numActiveEdges] = edge; + numActiveEdges++; + } + + /** + * Intersects all active edges, sorts them according to their intersection + * points and packs the array to remove unneeded edges. This does also + * remove any edges that do not intersect the scanline (i.e. they end above + * of the scanline). + * + * @param y the scanline height + */ + void intersectSortAndPack(int n, int y) + { + // Intersect and pack in one go. + int last = 0; + PolyEdge tmp; + for (int i = 0; i < numActiveEdges; i++) + { + PolyEdge edge = activeEdges[i]; + // Clear out edge that ends above the scanline. + if (edge != null && edge.y1 >= y) + { + assert edge.y1 >= y && edge.y0 <= y : "edge must cross scanline"; + edge.intersect(n, y); + activeEdges[last] = edge; + last++; + + // Bubble up the added edge. + for (int j = last - 1; j > 0; j--) + { + if (activeEdges[j].xIntersection + < activeEdges[j - 1].xIntersection) + { + tmp = activeEdges[j]; + activeEdges[j] = activeEdges[j - 1]; + activeEdges[j - 1] = tmp; + } + else + { + // The beginning of the list is already sorted. + break; + } + } + } + } + numActiveEdges = last; + + } + + /** + * Returns the number of active edges. This is only reliable after a + * call to {@link #intersectSortAndPack(int, int)}. + * + * @return the number of active edges + */ + int getNumActiveEdges() + { + return numActiveEdges; + } + + /** + * Returns the active edge at the position <code>i</code>. + * + * @param i the index + * + * @return the active edge at the specified index + */ + PolyEdge getActiveEdge(int i) + { + return activeEdges[i]; + } + + /** + * Removes all edges that end above the specified height. + * + * @param y the cut-off height + */ + void remove(int y) + { + for (int i = 0; i < numActiveEdges; i++) + { + PolyEdge edge = activeEdges[i]; + if (edge != null && edge.y1 < y) + { + activeEdges[i] = null; + } + } + } + + public String toString() + { + CPStringBuilder s = new CPStringBuilder(); + s.append("[ActiveEdges] "); + for (int i = 0; i < numActiveEdges; i++) + { + s.append(activeEdges[i]); + s.append(','); + } + return s.toString(); + } +} |