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Added option to use pxCache and also length check on Markers to avoid crash #1147

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merged 2 commits into from
Feb 26, 2022
+53 −23
Merged

Added option to use pxCache and also length check on Markers to avoid crash #1147

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2614799
added option to use pxCache and also length check on Markers to avoid…
ibrierley Feb 2, 2022
7a32d7d
adjust comments as suggested
ibrierley Feb 26, 2022
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76 changes: 53 additions & 23 deletions lib/src/layer/marker_layer.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,10 @@ import 'package:latlong2/latlong.dart';
class MarkerLayerOptions extends LayerOptions {
final List<Marker> markers;

/// Toggle marker position caching. Enabling will improve performance, but may introducen
/// errors when adding/removing markers. Default is enabled (`true`).
final bool usePxCache;

/// If true markers will be counter rotated to the map rotation
final bool? rotate;

Expand Down Expand Up @@ -38,6 +42,7 @@ class MarkerLayerOptions extends LayerOptions {
this.rotate = false,
this.rotateOrigin,
this.rotateAlignment = Alignment.center,
this.usePxCache = true,
Stream<Null>? rebuild,
}) : super(key: key, rebuild: rebuild);
}
Expand Down Expand Up @@ -190,11 +195,31 @@ class _MarkerLayerState extends State<MarkerLayer> {
// https://stackoverflow.com/questions/15943890/is-there-a-performance-benefit-in-using-fixed-length-lists-in-dart
var _pxCache = <CustomPoint>[];

// Calling this every time markerOpts change should guarantee proper length
List<CustomPoint> generatePxCache() => List.generate(
/// Calling this every time markerOpts change should guarantee proper length
List<CustomPoint> generatePxCache() {
if (widget.markerLayerOptions.usePxCache) {
return List.generate(
widget.markerLayerOptions.markers.length,
(i) => widget.map.project(widget.markerLayerOptions.markers[i].point),
);
}
return [];
}

bool updatePxCacheIfNeeded() {
var didUpdate = false;

/// markers may be modified, so update cache. Note, someone may
/// have not added to a cache, but modified, so this won't catch
/// this case. Parent widget setState should be called to call
/// didUpdateWidget to force a cache reload
if (widget.markerLayerOptions.markers.length != _pxCache.length) {
_pxCache = generatePxCache();
didUpdate = true;
}
return didUpdate;
}

@override
void initState() {
Expand All @@ -214,15 +239,22 @@ class _MarkerLayerState extends State<MarkerLayer> {
return StreamBuilder<int?>(
stream: widget.stream, // a Stream<int> or null
builder: (BuildContext context, AsyncSnapshot<int?> snapshot) {
var layerOptions = widget.markerLayerOptions;
var map = widget.map;
var usePxCache = layerOptions.usePxCache;
var markers = <Widget>[];
final sameZoom = widget.map.zoom == lastZoom;
for (var i = 0; i < widget.markerLayerOptions.markers.length; i++) {
var marker = widget.markerLayerOptions.markers[i];
final sameZoom = map.zoom == lastZoom;

var cacheUpdated = updatePxCacheIfNeeded();

for (var i = 0; i < layerOptions.markers.length; i++) {
var marker = layerOptions.markers[i];

// Decide whether to use cached point or calculate it
var pxPoint =
sameZoom ? _pxCache[i] : widget.map.project(marker.point);
if (!sameZoom) {
var pxPoint = usePxCache && (sameZoom || cacheUpdated)
? _pxCache[i]
: map.project(marker.point);
if (!sameZoom && usePxCache) {
_pxCache[i] = pxPoint;
}

Expand All @@ -231,23 +263,21 @@ class _MarkerLayerState extends State<MarkerLayer> {
var sw = CustomPoint(pxPoint.x + width, pxPoint.y - height);
var ne = CustomPoint(pxPoint.x - width, pxPoint.y + height);

if (!widget.map.pixelBounds.containsPartialBounds(Bounds(sw, ne))) {
if (!map.pixelBounds.containsPartialBounds(Bounds(sw, ne))) {
continue;
}

final pos = pxPoint - widget.map.getPixelOrigin();
final markerWidget =
(marker.rotate ?? widget.markerLayerOptions.rotate ?? false)
// Counter rotated marker to the map rotation
? Transform.rotate(
angle: -widget.map.rotationRad,
origin: marker.rotateOrigin ??
widget.markerLayerOptions.rotateOrigin,
alignment: marker.rotateAlignment ??
widget.markerLayerOptions.rotateAlignment,
child: marker.builder(context),
)
: marker.builder(context);
final pos = pxPoint - map.getPixelOrigin();
final markerWidget = (marker.rotate ?? layerOptions.rotate ?? false)
// Counter rotated marker to the map rotation
? Transform.rotate(
angle: -map.rotationRad,
origin: marker.rotateOrigin ?? layerOptions.rotateOrigin,
alignment:
marker.rotateAlignment ?? layerOptions.rotateAlignment,
child: marker.builder(context),
)
: marker.builder(context);

markers.add(
Positioned(
Expand All @@ -260,7 +290,7 @@ class _MarkerLayerState extends State<MarkerLayer> {
),
);
}
lastZoom = widget.map.zoom;
lastZoom = map.zoom;
return Container(
child: Stack(
children: markers,
Expand Down