sascha@424: package de.intevation.gnv.raster;
sascha@424:
sascha@779: import gnu.trove.TIntObjectHashMap;
sascha@779: import gnu.trove.TIntStack;
sascha@779:
sascha@779: import java.util.ArrayList;
sascha@424: import java.util.BitSet;
sascha@424: import java.util.List;
sascha@424:
sascha@445: import org.apache.log4j.Logger;
sascha@445:
sascha@424: /**
sascha@801: * Instances of this class are able to vectorize 2D integer arrays
sascha@801: * with a kind of flood filling regions detection mechanism to
sascha@801: * a set of line strings and polygons.
sascha@801: *
sascha@780: * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
sascha@424: */
sascha@424: public class Vectorizer
sascha@424: {
sascha@445: private static Logger log = Logger.getLogger(Vectorizer.class);
sascha@445:
sascha@801: /**
sascha@801: * Callback to process the found line strings and polygons.
sascha@801: */
sascha@424: public interface RingsHandler {
sascha@424:
sascha@801: /**
sascha@801: * Called from {@link #process(de.intevation.gnv.raster.Vectorizer.RingsHandler) }
sascha@801: * to give the found features to the postprocessing backend.
sascha@801: * @param rings The found line strings and polygons.
sascha@801: * @param value The integer value of the raster surrounded by
sascha@801: * the features.
sascha@801: * @param width The width of the index space of the vectorized data.
sascha@801: * @param height The height of the index space of the vectorized data.
sascha@801: */
sascha@436: void handleRings(
sascha@436: List<Edge> rings,
sascha@778: int value,
sascha@436: int width,
sascha@436: int height);
sascha@424:
sascha@424: } // interface RingsHandler
sascha@424:
sascha@801: /**
sascha@801: * Doubly link list representing a line string or a polygon.
sascha@801: */
sascha@424: public static final class Edge {
sascha@424:
sascha@801: /**
sascha@801: * The predecessor.
sascha@801: */
sascha@424: public Edge prev;
sascha@801: /**
sascha@801: * The successor.
sascha@801: */
sascha@424: public Edge next;
sascha@424:
sascha@801: /**
sascha@801: * Index of first vertex. To separate x and y values
sascha@801: * you have to divide the value by the width of the
sascha@801: * index space.
sascha@801: */
sascha@424: public int a;
sascha@801: /**
sascha@801: * Index of second vertex. To separate x and y values
sascha@801: * you have to divide the value by the width of the
sascha@801: * index space.
sascha@801: */
sascha@424: public int b;
sascha@424:
sascha@801: /**
sascha@801: * Default constructor.
sascha@801: */
sascha@424: public Edge() {
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Constructor to create Edge with two vertices.
sascha@801: * @param a The first vertex.
sascha@801: * @param b The second vertex.
sascha@801: */
sascha@424: public Edge(int a, int b) {
sascha@424: this.a = a;
sascha@424: this.b = b;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Copy constructor
sascha@801: * @param other The edge to clone.
sascha@801: */
sascha@437: public Edge(Edge other) {
sascha@437: a = other.a;
sascha@437: b = other.b;
sascha@437: }
sascha@437:
sascha@801: /**
sascha@801: * Chain a given edge segment to this segment. The
sascha@801: * side of the chaining is determined by a given
sascha@801: * parameter.
sascha@801: * @param other The segment to chain.
sascha@801: * @param found The side to chain.
sascha@801: */
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@801: /**
sascha@801: * Tells if the list is complete which means that this
sascha@801: * edge list is a closed polygon.
sascha@801: * @return true if edge list is closed else false.
sascha@801: */
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@801: /**
sascha@801: * Returns the length of this edge list in next direction.
sascha@801: * Segments in prev direction are ignored.
sascha@801: * @return The length of this edge list.
sascha@801: */
sascha@424: public int length() {
sascha@424: int length = 0;
sascha@424: Edge current = this;
sascha@778: do { ++length; }
sascha@437: while ((current = current.next) != null && current != this);
sascha@424: return length;
sascha@424: }
sascha@436:
sascha@801: /**
sascha@801: * Returns the head node of this edge list.
sascha@801: * @return The head node.
sascha@801: */
sascha@801: public Edge head() {
sascha@801: Edge current = this;
sascha@801: while (current.prev != null) {
sascha@801: current = current.prev;
sascha@801: }
sascha@801: return current;
sascha@801: }
sascha@447:
sascha@801: /**
sascha@801: * Hashes the two vertex indices to a common value.
sascha@801: * @return The hash value.
sascha@801: */
sascha@801: @Override
sascha@436: public int hashCode() {
sascha@436: return (a << 16) | b;
sascha@436: }
sascha@436:
sascha@801: /**
sascha@801: * Two edges are considered equal if they have the same
sascha@801: * a and b vertices.
sascha@801: * @param other The other edge.
sascha@801: * @return true if the edges are equal else false.
sascha@801: */
sascha@801: @Override
sascha@436: public boolean equals(Object other) {
sascha@436: Edge e = (Edge)other;
sascha@436: return a == e.a && b == e.b;
sascha@436: }
sascha@424: } // class Edge
sascha@424:
sascha@801: /**
sascha@801: * Simplifies a given edge list by removing collinear vertices.
sascha@801: * Attention: The original list is modified.
sascha@801: * @param edge The edge list to simplify.
sascha@801: * @param width The width of the vertex index space.
sascha@801: * @return The simplified list.
sascha@801: */
sascha@424: protected static Edge simplify(Edge edge, int width) {
sascha@424:
sascha@447: Edge e1 = edge, start = edge;
sascha@424:
sascha@424: int length = edge.length();
sascha@424:
sascha@437: if (length < 2) {
sascha@437: return e1;
sascha@437: }
sascha@437:
sascha@447: Edge e2 = edge.next;
sascha@447:
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@447: int e2x = e1.b % width;
sascha@447: int e2y = e1.b / width;
sascha@447: int e3x = e2.b % width;
sascha@447: int e3y = e2.b / width;
sascha@424:
sascha@424: if ((e1x == e2x && e2x == e3x && e1x == e3x)
sascha@447: || (e1y == e2y && e2y == e3y && e1y == e3y)) {
sascha@447: e1.b = e2.b;
sascha@447: Edge removed = e1.next;
sascha@447: e1.next = e2.next;
sascha@447: if (e1.next != null) {
sascha@447: e1.next.prev = e1;
sascha@447: }
sascha@447: e2 = e1.next;
sascha@424: count = 0;
sascha@424: --length;
sascha@447: if (removed == start) {
sascha@447: start = e1;
sascha@447: }
sascha@424: }
sascha@424: else {
sascha@424: e1 = e1.next;
sascha@424: e2 = e2.next;
sascha@424: ++count;
sascha@424: }
sascha@424: }
sascha@447: while (length > 1 && e2 != null && count < length + 2);
sascha@424:
sascha@447: return start;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * The raster to be traced.
sascha@801: */
sascha@424: protected int [] raster;
sascha@801: /**
sascha@801: * The width of the raster.
sascha@801: */
sascha@424: protected int width;
sascha@801: /**
sascha@801: * Map of the currently open edges.
sascha@801: */
sascha@424: protected TIntObjectHashMap openEdges;
sascha@801: /**
sascha@801: * List of rings already found.
sascha@801: */
sascha@436: protected List<Edge> rings;
sascha@801: /**
sascha@801: * Flag to signal if a simplification should be performed
sascha@801: * after a ring is completed.
sascha@801: */
sascha@436: protected boolean simplify;
sascha@424:
sascha@801: /**
sascha@801: * Default constructor. Simplification is turned on.
sascha@801: */
sascha@424: public Vectorizer() {
sascha@436: this(true);
sascha@436: }
sascha@436:
sascha@801: /**
sascha@801: * Constructor to create a vectorized with an explicit
sascha@801: * simplification policy.
sascha@801: * @param simplify Indicates if simplification should be
sascha@801: * used on ring completion.
sascha@801: */
sascha@436: public Vectorizer(boolean simplify) {
sascha@436: openEdges = new TIntObjectHashMap();
sascha@436: rings = new ArrayList<Edge>();
sascha@436: this.simplify = simplify;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Constructor to create a vectorizer with a given raster and width.
sascha@801: * Simplification is turn on.
sascha@801: * @param raster The raster to be vectorized.
sascha@801: * @param width The width of the raster.
sascha@801: */
sascha@424: public Vectorizer(int [] raster, int width) {
sascha@445: this(true, raster, width);
sascha@445: }
sascha@445:
sascha@801: /**
sascha@801: * Constructor to create a vectorizer with a given raster, width
sascha@801: * and an explicit simplification policy.
sascha@801: * @param simplify Indicates if simplification should be
sascha@801: * used on ring completion.
sascha@801: * @param raster The raster to be vectorized.
sascha@801: * @param width The width of the raster.
sascha@801: */
sascha@445: public Vectorizer(boolean simplify, int [] raster, int width) {
sascha@445: this(simplify);
sascha@424: this.raster = raster;
sascha@424: this.width = width;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Returns (x, y+1) for given vertex in index space.
sascha@801: * @param i vertex in index space.
sascha@801: * @param w width of raster.
sascha@801: * @return (x, y+1) in index space.
sascha@801: */
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@801: /**
sascha@801: * Returns tl(i, w) + 1.
sascha@801: * @param i vertex in index space.
sascha@801: * @param w width of raster.
sascha@801: * @return tl(i, w) + 1.
sascha@801: */
sascha@424: public static final int tr(int i, int w) {
sascha@424: return tl(i, w) + 1;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Returns tl(i, w) + w + 1.
sascha@801: * @param i vertex in index space.
sascha@801: * @param w width of raster.
sascha@801: * @return tl(i, w) + w + 1.
sascha@801: */
sascha@424: public static final int bl(int i, int w) {
sascha@424: return tl(i, w) + w + 1;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Returns bl(i, w) + 1.
sascha@801: * @param i vertex in index space.
sascha@801: * @param w width of raster.
sascha@801: * @return bl(i, w) + 1.
sascha@801: */
sascha@424: public static final int br(int i, int w) {
sascha@424: return bl(i, w) + 1;
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Resets open resources after a set of features were found.
sascha@801: */
sascha@424: protected void resetRegion() {
sascha@424: openEdges.clear();
sascha@424: rings.clear();
sascha@424: }
sascha@424:
sascha@801: /**
sascha@801: * Adds an edge to the map of open edges, joins it
sascha@801: * with its direct neighbors of if complete add the
sascha@801: * list to the complete features.
sascha@801: * @param edge
sascha@801: */
sascha@424: protected void emit(Edge edge) {
sascha@424:
sascha@424: Edge otherA = (Edge)openEdges.remove(edge.a);
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@436: rings.add(simplify ? simplify(edge, width + 1) : edge);
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@801: /**
sascha@801: * Vectorize the raster. The found features are fed into
sascha@801: * the given ring handler.
sascha@801: * @param handler The RingHandler to postprocess the found features.
sascha@801: * @return The number of regions found.
sascha@801: */
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@436: int height = raster.length / width;
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@436: handler.handleRings(
sascha@778: rings,
sascha@778: currentValue,
sascha@436: width + 1,
sascha@436: height + 1);
sascha@424:
sascha@424: resetRegion();
sascha@424: }
sascha@424:
sascha@424: return regions;
sascha@424: }
sascha@424: }
sascha@798: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :