printing accuracy to screen

src/javascript/controllers/HeightMapViewController.js

@@ -21,9 +21,11 @@ class HeightMapViewController extends UIViewController {
 		this.lastX         = 0;
 		this.translated    = 0;
 		this.isCapturing   = false;
+		this.currentAcc    = 0;
 		this.addSubview(new MapController("#osm", this.model));
 
 		navigator.geolocation.watchPosition(position => {
+			this.currentAcc = position.coords.accuracy;
 			if (!this.isCapturing || position.coords.accuracy > 10)
 				return;
 			this.addPoint(new GeoPoint(
@@ -178,11 +180,13 @@ class HeightMapViewController extends UIViewController {
 		ctx.font = "bold 23px Arial";
 		ctx.textAlign = "right";
 		ctx.fillText(`Datapoints: ${this.model.points.length}`, this.canvas.width - 20 , 32);
+		ctx.fillText(`Accuracy: ${this.currentAcc}m`, this.canvas.width - 20, this.canvas.height - 20);
 		ctx.textAlign = "left";
 		ctx.font = "18px Arial";
 		ctx.fillText(`– ${Math.round(this.model.min)}m`, 10, height - 22);
 		ctx.fillText(`– ${Math.round(this.model.max)}m`, 10, 32);
 
+		/*   draw "play button"   */
 		if (!this.isCapturing) {
 			let theight = 100;
 			let twidth  = 80;