From 42f5b5e26ec3f4e15704824539434029d022e049 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Lehni?= <juerg@scratchdisk.com>
Date: Sun, 5 Jun 2011 21:28:49 +0100
Subject: [PATCH] =?UTF-8?q?Implement=20Douglas=E2=80=93Peucker=20algorithm?=
 =?UTF-8?q?=20for=20point=20reduction=20before=20the=20curve=20fitting.?=
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---
 src/path/PathFitter.js | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/path/PathFitter.js b/src/path/PathFitter.js
index 809e7bc5..6aab8742 100644
--- a/src/path/PathFitter.js
+++ b/src/path/PathFitter.js
@@ -31,6 +31,7 @@ var PathFitter = Base.extend({
 				prev = point;
 			}
 		}
+		this.points = this.reducePoints(this.points, 1);
 		this.error = error;
 		this.iterationError = error * error;
 	},
@@ -46,6 +47,28 @@ var PathFitter = Base.extend({
 		return this.segments;
 	},
 
+	// Douglas–Peucker algorithm
+	reducePoints: function(points, tolerance) {
+		var line = new Line(points[0], points[points.length - 1], false);
+		var maxDistance = 0,
+			maxIndex = 0;
+		for (var i = 1; i < points.length - 1; i++) {
+			var distance = line.getDistance(points[i]);
+			if(distance > maxDistance) {
+				maxDistance = distance;
+				maxIndex = i;
+			}
+		}
+		if (maxDistance >= tolerance) {
+			var pts = this.reducePoints(
+					points.slice(0, maxIndex + 1), tolerance);
+			pts.pop();
+			return pts.concat(this.reducePoints(
+					points.slice(maxIndex, points.length), tolerance));
+		}
+		return [points[0], points[points.length - 1]];
+	},
+
 	// Fit a Bezier curve to a (sub)set of digitized points
 	fitCubic: function(first, last, tHat1, tHat2) {
 		//	Use heuristic if region only has two points in it