start of an API for GeometryBuffer

- fix bug in ensure size

src/org/oscim/core/GeometryBuffer.java

@@ -1,42 +1,163 @@
 package org.oscim.core;
 
 public class GeometryBuffer {
+
+	// TODO
+	// -- check indexPos < Short.Max
+	final static boolean CHECK_STATE = true;
+
 	public float[] points;
 	public short[] index;
 	public int indexPos;
 	public int pointPos;
 
-	public GeometryBuffer(float[] points, short[] index){
+	public int mode;
+
+	public GeometryBuffer(float[] points, short[] index) {
+		if (points == null)
+			throw new IllegalArgumentException("GeometryBuffer points is null");
+		if (index == null)
+			throw new IllegalArgumentException("GeometryBuffer index is null");
+
 		this.points = points;
 		this.index = index;
+		mode = 0;
+		indexPos = 0;
+		pointPos = 0;
 	}
+
 	public GeometryBuffer(int numPoints, int numIndices) {
 		this.points = new float[numPoints * 2];
 		this.index = new short[numIndices];
 	}
 
-	public float[] ensurePointSize(int size, boolean copy){
+	// ---- API ----
+	public void clear() {
+		index[0] = -1;
+		indexPos = 0;
+		pointPos = 0;
+		mode = 0;
+	}
+
+	public void addPoint(float x, float y) {
+		if (pointPos >= points.length - 1)
+			ensurePointSize((pointPos >> 1) + 1, true);
+
+		points[pointPos++] = x;
+		points[pointPos++] = y;
+
+		index[indexPos] += 2;
+	}
+
+	public void setPoint(int pos, float x, float y) {
+		points[(pos << 1) + 0] = x;
+		points[(pos << 1) + 1] = y;
+	}
+
+	public void startPoints() {
+		if (CHECK_STATE)
+			setOrCheckMode(1);
+	}
+
+	public void startLine() {
+		if (CHECK_STATE)
+			setOrCheckMode(2);
+
+		if (index[0] >= 0){
+			// start next
+			if (++indexPos >= index.length)
+				ensureIndexSize(indexPos, true);
+		}
+
+		// initialize with zero points
+		index[indexPos] = 0;
+		// set new end marker
+		index[indexPos + 1] = -1;
+	}
+
+	public void startPolygon() {
+		if (CHECK_STATE)
+			setOrCheckMode(3);
+
+		if ((indexPos + 4) >= index.length)
+			ensureIndexSize(indexPos + 4, true);
+
+		if (indexPos > 0) {
+
+			// end ring
+			index[++indexPos] = 0;
+
+			// end polygon
+			index[++indexPos] = 0;
+
+			// next polygon start
+			indexPos++;
+		}
+
+		// initialize with zero points
+		index[indexPos] = 0;
+		// set new end marker
+		index[indexPos + 1] = -1;
+	}
+
+	public void startHole() {
+		if (CHECK_STATE)
+			checkMode(3);
+
+		if ((indexPos + 3) >= index.length)
+			ensureIndexSize(indexPos, true);
+
+		// end ring
+		index[++indexPos] = 0;
+
+		// initialize with zero points
+		index[++indexPos] = 0;
+
+		// set new end marker
+		index[indexPos + 1] = -1;
+	}
+
+
+
+	// ---- internals ----
+	public float[] ensurePointSize(int size, boolean copy) {
 		if (size * 2 < points.length)
 			return points;
 
 		float[] tmp = new float[size * 2 + 1024];
 		if (copy)
-			System.arraycopy(tmp, 0, points, 0, points.length);
+			System.arraycopy(points, 0, tmp, 0, points.length);
 
 		points = tmp;
 		return points;
 	}
 
-	public short[] ensureIndexSize(int size, boolean copy){
+	public short[] ensureIndexSize(int size, boolean copy) {
 		if (size < index.length)
 			return index;
 
 		short[] tmp = new short[size + 128];
 		if (copy)
-			System.arraycopy(tmp, 0, index, 0, index.length);
+			System.arraycopy(index, 0, tmp, 0, index.length);
 
 		index = tmp;
 
 		return index;
 	}
+
+	private void setOrCheckMode(int m) {
+		if (mode == m)
+			return;
+
+		if (mode != 0)
+			throw new IllegalArgumentException("GeometryBuffer not cleared " + m + "<>" + mode);
+
+		mode = m;
+	}
+
+	private void checkMode(int m) {
+		if (mode != m)
+			throw new IllegalArgumentException("GeometryBuffer not cleared " + m + "<>" + mode);
+	}
+
 }