sascha@424: package de.intevation.gnv.raster;
sascha@424: 
sascha@424: import java.util.BitSet;
sascha@424: import java.util.List;
sascha@424: import java.util.ArrayList;
sascha@424: 
sascha@424: import gnu.trove.TIntStack;
sascha@424: import gnu.trove.TIntObjectHashMap;
sascha@424: 
sascha@424: /**
sascha@424:  * @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
sascha@424:  */
sascha@424: public class Vectorizer
sascha@424: {
sascha@424:     public interface RingsHandler {
sascha@424: 
sascha@424:         void handleRings(List rings, int value, int width);
sascha@424: 
sascha@424:     } // interface RingsHandler
sascha@424: 
sascha@424:     public static final class Edge {
sascha@424: 
sascha@424:         public Edge prev;
sascha@424:         public Edge next;
sascha@424: 
sascha@424:         public int a;
sascha@424:         public int b;
sascha@424: 
sascha@424:         public Edge() {
sascha@424:         }
sascha@424: 
sascha@424:         public Edge(int a, int b) {
sascha@424:             this.a = a;
sascha@424:             this.b = b;
sascha@424:         }
sascha@424: 
sascha@424:         public void chain(Edge other, int found) {
sascha@424: 
sascha@424:             if (found == a) {
sascha@424:                 other.next = this;
sascha@424:                 prev = other;
sascha@424:                 return;
sascha@424:             }
sascha@424: 
sascha@424:             if (found == b) {
sascha@424:                 next = other;
sascha@424:                 other.prev = this;
sascha@424:                 return;
sascha@424:             }
sascha@424: 
sascha@424:             throw new IllegalStateException("cannot chain");
sascha@424:         }
sascha@424: 
sascha@424:         public boolean isComplete() {
sascha@424:             Edge current = this;
sascha@424:             do {
sascha@424:                 if (current.prev == null || current.next == null) {
sascha@424:                     return false;
sascha@424:                 }
sascha@424:                 current = current.next;
sascha@424:             }
sascha@424:             while (current != this);
sascha@424:             return true;
sascha@424:         }
sascha@424: 
sascha@424:         public int length() {
sascha@424:             int length = 0;
sascha@424:             Edge current = this;
sascha@424:             do { ++length; } while ((current = current.next) != this);
sascha@424:             return length;
sascha@424:         }
sascha@424:     } // class Edge
sascha@424: 
sascha@424:     protected static Edge simplify(Edge edge, int width) {
sascha@424: 
sascha@424:         Edge e1 = edge;
sascha@424:         Edge e2 = edge.next;
sascha@424:         Edge e3 = e2.next;
sascha@424: 
sascha@424:         int length = edge.length();
sascha@424: 
sascha@424:         int count = 0;
sascha@424: 
sascha@424:         do {
sascha@424:             int e1x = e1.a % width;
sascha@424:             int e1y = e1.a / width;
sascha@424:             int e2x = e2.a % width;
sascha@424:             int e2y = e2.a / width;
sascha@424:             int e3x = e3.a % width;
sascha@424:             int e3y = e3.a / width;
sascha@424: 
sascha@424:             if ((e1x == e2x && e2x == e3x && e1x == e3x)
sascha@424:             ||  (e1y == e2y && e2y == e3y && e1y == e3y)) {
sascha@424:                 e1.next = e3;
sascha@424:                 e3.prev = e1;
sascha@424:                 e2 = e3;
sascha@424:                 e3 = e2.next;
sascha@424:                 count = 0;
sascha@424:                 --length;
sascha@424:             }
sascha@424:             else {
sascha@424:                 e1 = e1.next;
sascha@424:                 e2 = e2.next;
sascha@424:                 e3 = e3.next;
sascha@424:                 ++count;
sascha@424:             }
sascha@424:         }
sascha@424:         while (count < length + 2);
sascha@424: 
sascha@424:         return e1;
sascha@424:     }
sascha@424: 
sascha@424:     protected int []            raster;
sascha@424:     protected int               width;
sascha@424:     protected TIntObjectHashMap openEdges;
sascha@424:     protected ArrayList         rings;
sascha@424: 
sascha@424:     public Vectorizer() {
sascha@424:         openEdges = new TIntObjectHashMap();
sascha@424:         rings     = new ArrayList();
sascha@424:     }
sascha@424: 
sascha@424:     public Vectorizer(int [] raster, int width) {
sascha@424:         this();
sascha@424:         this.raster = raster;
sascha@424:         this.width  = width;
sascha@424:     }
sascha@424: 
sascha@424:     public static final int tl(int i, int w) {
sascha@424:         int x = i % w;
sascha@424:         int y = i / w;
sascha@424:         return x + (w + 1)*y;
sascha@424:     }
sascha@424: 
sascha@424:     public static final int tr(int i, int w) {
sascha@424:         return tl(i, w) + 1;
sascha@424:     }
sascha@424: 
sascha@424:     public static final int bl(int i, int w) {
sascha@424:         return tl(i, w) + w + 1;
sascha@424:     }
sascha@424: 
sascha@424:     public static final int br(int i, int w) {
sascha@424:         return bl(i, w) + 1;
sascha@424:     }
sascha@424: 
sascha@424:     protected void resetRegion() {
sascha@424:         openEdges.clear();
sascha@424:         rings.clear();
sascha@424:     }
sascha@424: 
sascha@424:     protected void emit(Edge edge) {
sascha@424: 
sascha@424:         Edge otherA = (Edge)openEdges.remove(edge.a);
sascha@424: 
sascha@424:         if (otherA != null) {
sascha@424:             otherA.chain(edge, edge.a);
sascha@424:         }
sascha@424: 
sascha@424:         Edge otherB = (Edge)openEdges.remove(edge.b);
sascha@424:         if (otherB != null) {
sascha@424:             otherB.chain(edge, edge.b);
sascha@424:         }
sascha@424: 
sascha@424:         if (edge.isComplete()) {
sascha@424:             rings.add(simplify(edge, width + 1));
sascha@424:         }
sascha@424:         else {
sascha@424:             if (otherA == null) {
sascha@424:                 openEdges.put(edge.a, edge);
sascha@424:             }
sascha@424:             if (otherB == null) {
sascha@424:                 openEdges.put(edge.b, edge);
sascha@424:             }
sascha@424:         }
sascha@424:     }
sascha@424: 
sascha@424:     public int process(RingsHandler handler) {
sascha@424: 
sascha@424:         BitSet visited = new BitSet(raster.length);
sascha@424: 
sascha@424:         TIntStack stack = new TIntStack();
sascha@424: 
sascha@424:         int regions = 0;
sascha@424: 
sascha@424: 
sascha@424:         for (int i = 0; i < raster.length; ++i) {
sascha@424:             if (visited.get(i)) {
sascha@424:                 continue;
sascha@424:             }
sascha@424: 
sascha@424:             ++regions;
sascha@424: 
sascha@424:             int currentValue = raster[i];
sascha@424:             visited.set(i);
sascha@424: 
sascha@424:             int current = i;
sascha@424:             visited.set(current);
sascha@424: 
sascha@424:             for (;;) {
sascha@424:                 int tl = tl(current, width);
sascha@424:                 int tr = tr(current, width);
sascha@424:                 int bl = bl(current, width);
sascha@424:                 int br = br(current, width);
sascha@424: 
sascha@424:                 int t = current - width;
sascha@424: 
sascha@424:                 if (t < 0) {
sascha@424:                     emit(new Edge(tr, tl));
sascha@424:                 }
sascha@424:                 else {
sascha@424:                     if (raster[t] != currentValue) {
sascha@424:                         emit(new Edge(tr, tl));
sascha@424:                     }
sascha@424:                     else {
sascha@424:                         if (!visited.get(t)) {
sascha@424:                             visited.set(t);
sascha@424:                             stack.push(t);
sascha@424:                         }
sascha@424:                     }
sascha@424:                 }
sascha@424: 
sascha@424:                 int b = current + width;
sascha@424: 
sascha@424:                 if (b >= raster.length) {
sascha@424:                     emit(new Edge(bl, br));
sascha@424:                 }
sascha@424:                 else {
sascha@424:                     if (raster[b] != currentValue) {
sascha@424:                         emit(new Edge(bl, br));
sascha@424:                     }
sascha@424:                     else {
sascha@424:                         if (!visited.get(b)) {
sascha@424:                             visited.set(b);
sascha@424:                             stack.push(b);
sascha@424:                         }
sascha@424:                     }
sascha@424:                 }
sascha@424: 
sascha@424:                 int x = current % width;
sascha@424: 
sascha@424:                 if (x == 0) {
sascha@424:                     emit(new Edge(tl, bl));
sascha@424:                 }
sascha@424:                 else {
sascha@424:                     int l = current - 1;
sascha@424:                     if (raster[l] != currentValue) {
sascha@424:                         emit(new Edge(tl, bl));
sascha@424:                     }
sascha@424:                     else {
sascha@424:                         if (!visited.get(l)) {
sascha@424:                             visited.set(l);
sascha@424:                             stack.push(l);
sascha@424:                         }
sascha@424:                     }
sascha@424:                 }
sascha@424: 
sascha@424:                 if (x == width - 1) {
sascha@424:                     emit(new Edge(br, tr));
sascha@424:                 }
sascha@424:                 else {
sascha@424:                     int r = current + 1;
sascha@424:                     if (raster[r] != currentValue) {
sascha@424:                         emit(new Edge(br, tr));
sascha@424:                     }
sascha@424:                     else {
sascha@424:                         if (!visited.get(r)) {
sascha@424:                             visited.set(r);
sascha@424:                             stack.push(r);
sascha@424:                         }
sascha@424:                     }
sascha@424:                 }
sascha@424: 
sascha@424:                 if (stack.size() == 0) {
sascha@424:                     break;
sascha@424:                 }
sascha@424: 
sascha@424:                 current = stack.pop();
sascha@424:             }
sascha@424: 
sascha@424:             handler.handleRings(rings, currentValue, width + 1);
sascha@424: 
sascha@424:             resetRegion();
sascha@424:         }
sascha@424: 
sascha@424:         return regions;
sascha@424:     }
sascha@424: }
sascha@424: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8: