Improve tile management (#572)

* imporve tile managment initial commit based on Leaflet

* abort improve

* let user control throttleUpdate behaviour via updateInterval

* let user controll throttleUpdate behaviour 2

* support fadeIn

* create throttle stream which supports trailing calls

* create trailing call Throttle (add missing util.dart)

* update Throttle stream which is independent of StreamController

* order tiles by zIndex

* start fade when Tile image loaded

* create Tile sort without any closure

* beauty code

* support minZoom minNativeZoom / maxNativeZoom

* remove Tiles when tileZoom is out of zoom limits and restore them when tileZoom is within limits

* fix -- Zooming out very far causes null pointers #59

* support zoomReverse / zoomOffset

* support error tile image / improve tile fade in (remove hacky solution)

* use direct milliseconds instead of Duration to avoid microseconds

* fix -- Exception caught by image resource service - not handled. #444

* remove diagnostic prints

lib/src/core/util.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:tuple/tuple.dart';
 
 var _templateRe = RegExp(r'\{ *([\w_-]+) *\}');
@@ -22,3 +24,36 @@ double wrapNum(double x, Tuple2<double, double> range, [bool includeMax]) {
  var d = max - min;
  return x == max && includeMax != null ? x : ((x - min) % d + d) % d + min;
 }
+
+StreamTransformer<T, T> throttleStreamTransformerWithTrailingCall<T>(
+ Duration duration) {
+ Timer timer;
+ T recentData;
+ var trailingCall = false;
+
+ void Function(T data, EventSink<T> sink) throttleHandler;
+ throttleHandler = (T data, EventSink<T> sink) {
+ recentData = data;
+
+ if (timer == null) {
+ sink.add(recentData);
+ timer = Timer(duration, () {
+ timer = null;
+
+ if (trailingCall) {
+ trailingCall = false;
+ throttleHandler(recentData, sink);
+ }
+ });
+ } else {
+ trailingCall = true;
+ }
+ };
+
+ return StreamTransformer<T, T>.fromHandlers(
+ handleData: throttleHandler,
+ handleDone: (EventSink<T> sink) {
+ timer?.cancel();
+ sink.close();
+ });
+}

lib/src/gestures/gestures.dart

@@ -236,8 +236,11 @@ abstract class MapGestureMixin extends State<FlutterMap>
  return Offset(point.x.toDouble(), point.y.toDouble());
  }
 
- double _getZoomForScale(double startZoom, double scale) =>
- startZoom + math.log(scale) / math.ln2;
+ double _getZoomForScale(double startZoom, double scale) {
+ var resultZoom = startZoom + math.log(scale) / math.ln2;
+
+ return map.fitZoomToBounds(resultZoom);
+ }
 
  @override
  void dispose() {