1 files changed, 55 insertions, 0 deletions
diff --git a/extlib/leaflet/src/geometry/PolyUtil.js b/extlib/leaflet/src/geometry/PolyUtil.js
new file mode 100644
index 00000000..c5460709
--- /dev/null
+++ b/extlib/leaflet/src/geometry/PolyUtil.js
@@ -0,0 +1,55 @@
+/*
+ * L.PolyUtil contains utilify functions for polygons (clipping, etc.). 
+ */
+
+L.PolyUtil = {};
+
+/*
+ * Sutherland-Hodgeman polygon clipping algorithm.
+ * Used to avoid rendering parts of a polygon that are not currently visible.
+ */
+L.PolyUtil.clipPolygon = function(points, bounds) {
+	var min = bounds.min,
+		max = bounds.max,
+		clippedPoints,
+		edges = [1, 4, 2, 8],
+		i, j, k,
+		a, b,
+		len, edge, p,
+		lu = L.LineUtil;
+	
+	for (i = 0, len = points.length; i < len; i++) {
+		points[i]._code = lu._getBitCode(points[i], bounds);
+	}
+	
+	// for each edge (left, bottom, right, top)
+	for (k = 0; k < 4; k++) {
+		edge = edges[k];
+		clippedPoints = [];
+		
+		for (i = 0, len = points.length, j = len - 1; i < len; j = i++) {
+			a = points[i];
+			b = points[j];
+			
+			// if a is inside the clip window
+			if (!(a._code & edge)) {
+				// if b is outside the clip window (a->b goes out of screen)
+				if (b._code & edge) {
+					p = lu._getEdgeIntersection(b, a, edge, bounds);
+					p._code = lu._getBitCode(p, bounds);
+					clippedPoints.push(p);
+				}
+				clippedPoints.push(a);
+				
+			// else if b is inside the clip window (a->b enters the screen)
+			} else if (!(b._code & edge)) {
+				p = lu._getEdgeIntersection(b, a, edge, bounds);
+				p._code = lu._getBitCode(p, bounds);
+				clippedPoints.push(p);
+			}
+		}
+		points = clippedPoints;
+	}
+	
+	return points;
+};
+\ No newline at end of file