fix for heightmap dragging

src/javascript/controllers/HeightMapViewController.js

@@ -24,13 +24,14 @@ class HeightMapViewController extends UIViewController {
 	constructor(view, model) {
 		super(view, model);
 
-		this.state         = Settings.get("mapState", States.HEIGHTMAP);
-		this.canvas        = null;
-		this.drag          = false;
-		this.lastX         = 0;
-		this.translated    = 0;
-		this.isCapturing   = false;
-		this.currentAcc    = 0;
+		this.state          = Settings.get("mapState", States.HEIGHTMAP);
+		this.canvas         = null;
+		this.drag           = false;
+		this.lastX          = 0;
+		this.translated     = 0;
+		this.isCapturing    = false;
+		this.currentAcc     = 0;
+		this.heightmapWidth = 0;
 		this.addSubview(new MapController("#osm", this.model));
 
 		/*   constantly checking the position of the user for changes   */
@@ -122,7 +123,7 @@ class HeightMapViewController extends UIViewController {
 			if (!this.drag)
 				return;
 			let delta = event.changedTouches[0].clientX - this.lastX;
-			if (this.translated + delta > 0 || (this.translated + delta) < (this.model.points.length * -40 + this.canvas.width))
+			if (this.translated + delta > 0 || (this.translated + delta) < (this.heightmapWidth - 40 + this.canvas.width))
 				return;
 			this.clear();
 			this.translated += delta;
@@ -167,6 +168,7 @@ class HeightMapViewController extends UIViewController {
 			num++;
 			lastPoint = point;
 		}
+		this.heightmapWidth = x;
 		ctx.lineTo(x - 40, height);
 		ctx.lineTo(0, height);
 		ctx.closePath();