X-Git-Url: http://gitweb.fperrin.net/?p=GpsPrune.git;a=blobdiff_plain;f=src%2Ftim%2Fprune%2Fdata%2FMidpointData.java;fp=src%2Ftim%2Fprune%2Fdata%2FMidpointData.java;h=3fdebb284ac1208d8352f2a35ea01419ed6b7bad;hp=0000000000000000000000000000000000000000;hb=ce6f2161b8596f7018d6a76bff79bc9e571f35fd;hpb=2d8cb72e84d5cc1089ce77baf1e34ea3ea2f8465

diff --git a/src/tim/prune/data/MidpointData.java b/src/tim/prune/data/MidpointData.java
new file mode 100644
index 0000000..3fdebb2
--- /dev/null
+++ b/src/tim/prune/data/MidpointData.java
@@ -0,0 +1,98 @@
+package tim.prune.data;
+
+/**
+ * Class to hold information about the mid-points between
+ * adjacent track points.  Used by the MapCanvas for creating
+ * points by dragging.
+ */
+public class MidpointData
+{
+	// track object
+	private Track _track = null;
+	// Scaled x, y values
+	private double[] _xValues = null;
+	private double[] _yValues = null;
+	// Validity flags
+	private boolean[] _valids = null;
+	// Flag to set data stale
+	private boolean _needRefresh = true;
+
+
+	/**
+	 * Flag the data as needing to be updated
+	 * @param inTrack track object from which to get the data
+	 */
+	public void updateData(Track inTrack)
+	{
+		_track = inTrack;
+		_needRefresh = true;
+	}
+
+	/**
+	 * Update the arrays of data from the track
+	 */
+	private synchronized void updateData()
+	{
+		_needRefresh = false;
+		if (_track == null) return;
+		// Make arrays the right size
+		final int numPoints = _track.getNumPoints();
+		if (_xValues == null || _xValues.length != numPoints)
+		{
+			_xValues = new double[numPoints];
+			_yValues = new double[numPoints];
+			_valids  = new boolean[numPoints];
+		}
+		if (numPoints <= 0) return;
+		_valids[0] = false;
+
+		// Loop over the points in the track
+		for (int i=1; i<numPoints; i++)
+		{
+			boolean pointValid = false;
+			DataPoint point = _track.getPoint(i);
+			if (point != null && !point.getSegmentStart() && !point.isWaypoint())
+			{
+				_xValues[i] = (_track.getX(i) + _track.getX(i-1)) / 2.0;
+				_yValues[i] = (_track.getY(i) + _track.getY(i-1)) / 2.0;
+				pointValid = true;
+			}
+			_valids[i] = pointValid;
+		}
+	}
+
+	/**
+	 * Find the nearest point to the specified x and y coordinates
+	 * or -1 if no point is within the specified max distance
+	 * @param inX x coordinate
+	 * @param inY y coordinate
+	 * @param inMaxDist maximum distance from selected coordinates
+	 * @return index of nearest point or -1 if not found
+	 */
+	public int getNearestPointIndex(double inX, double inY, double inMaxDist)
+	{
+		if (_track == null) return -1;
+		if (_needRefresh) updateData();
+		final int numPoints = _track.getNumPoints();
+		int nearestPoint = 0;
+		double nearestDist = -1.0;
+		double currDist;
+		for (int i=1; i < numPoints; i++)
+		{
+			if (_valids[i])
+			{
+				currDist = Math.abs(_xValues[i] - inX) + Math.abs(_yValues[i] - inY);
+				if (currDist < nearestDist || nearestDist < 0.0)
+				{
+					nearestPoint = i;
+					nearestDist = currDist;
+				}
+			}
+		}
+		// Check whether it's within required distance
+		if (nearestDist > inMaxDist && inMaxDist > 0.0) {
+			return -1;
+		}
+		return nearestPoint;
+	}
+}