I have a component that has a map with multiple custom markers for various locations and a carousel with cards for those same locations. When a user presses a marker, it should show the callout and show the location's name next to the marker (but outside of the callout).
However, because I update the state in onRegionChangeComplete
, if the user moves the map and then quickly presses the marker (before the state finishes updating from calling setState
in onRegionChangeComplete
), then the markers will re-render before firing the onPress
event, and the event is never fired.
One solution might be to use shouldComponentUpdate
, however, the docs state that it should only be used for performance optimization and not to prevent re-renders (https://reactjs.org/docs/react-component.html#shouldcomponentupdate), but more importantly, my componentDidUpdate
function has some conditional logic dependent on the region set in shouldComponentUpdate
, as well as other conditional actions, so I don't want to prevent re-rendering of the entire component, just unnecessary re-rendering of the markers.
I'm also using the performance optimization mentioned in https://github.com/react-native-community/react-native-maps/issues/2082 of wrapping the makers in a component that implements shouldComponentUpdate
and getDerivedStateFromProps
, however, I'm not entirely sure this is doing anything because it seems like the parent component is just recreating all of my optimized markers rather than using their optimizations to handle re-rendering. Also, even if I don't use a wrapped marker but a conventional custom marker, I still have the same issues.
I've also opened an issue for this on react-native-maps but haven't gotten a response yet: https://github.com/react-native-community/react-native-maps/issues/2860
My 'onRegionComplete' function that updates state when map is moved. I removed a few other conditional state updates for brevity:
onRegionChangeComplete = (region) => {
const nextState = { };
nextState.region = region;
if (this.state.showNoResultsCard) {
nextState.showNoResultsCard = false;
}
.
.
.
this.setState({ ...nextState });
this.props.setSearchRect({
latitude1: region.latitude + (region.latitudeDelta / 2),
longitude1: region.longitude + (region.longitudeDelta / 2),
latitude2: region.latitude - (region.latitudeDelta / 2),
longitude2: region.longitude - (region.longitudeDelta / 2)
});
}
MapView using the more conventional marker (not the optomized version):
<MapView // show if loaded or show a message asking for location
provider={PROVIDER_GOOGLE}
style={{ flex: 1, minHeight: 200, minWidth: 200 }}
initialRegion={constants.initialRegion}
ref={this.mapRef}
onRegionChange={this.onRegionChange}
onRegionChangeComplete={this.onRegionChangeComplete}
showsUserLocationButton={false}
showsPointsOfInterest={false}
showsCompass={false}
moveOnMarkerPress={false}
onMapReady={this.onMapReady}
customMapStyle={mapStyle}
zoomTapEnabled={false}
>
{this.state.isMapReady && this.props.places.map((place, index) => {
const calloutText = this.getDealText(place, 'callout');
return (
<Marker
tracksViewChanges
key={Shortid.generate()}
ref={(ref) => { this.markers[index] = ref; }}
coordinate={{
latitude: place.getLatitude(),
longitude: place.getLongitude()
}}
onPress={() => { this.onMarkerSelect(index); }}
anchor={{ x: 0.05, y: 0.9 }}
centerOffset={{ x: 400, y: -60 }}
calloutOffset={{ x: 8, y: 0 }}
calloutAnchor={{ x: 0.075, y: 0 }}
image={require('../../Assets/icons8-marker-80.png')}
style={index === this.state.scrollIndex ? { zIndex: 2 } : null}
>
{this.state.scrollIndex === index &&
<Text style={styles.markerTitle}>{place.getName()}</Text>}
<Callout onPress={() => this.onCalloutTap(place)} tooltip={false}>
<View style={{
borderColor: red,
width: 240,
borderWidth: 0,
borderRadius: 20,
paddingHorizontal: 8,
flexDirection: 'column',
justifyContent: 'flex-start',
alignItems: 'center'
}}
>
<Text style={styles.Title}>Now:</Text>
<View style={{
width: 240,
flexDirection: 'column',
justifyContent: 'space-evenly',
alignItems: 'flex-start',
paddingHorizontal: 8,
flex: 1
}}
>
{calloutText.Text}
</View>
</View>
</Callout>
</Marker>
);
})
}
</MapView>
My function for the marker's on press event:
onMarkerSelect(index) {
this.setState({ scrollIndex: index });
this.carousel._component.scrollToIndex({
index,
animated: true,
viewOffset: 0,
viewPosition: 0.5
});
this.markers[index].redrawCallout();
}
Updating state and then quickly pressing a marker will cause the onPress event not to fire. Also, the markers are re-rendered/recreated every time a parent component is updated. (I say recreated because it seems like the markers are re-rendering without even firing shouldComponentUpdat
e or componentDidUpdate
).
Is there any way to update state in onRegionChangeComplete
without forcing the markers to re-render?
For anyone else who happens to have this problem, the issue was that I was randomly generating the keys for the markers, causing the parent component to create new markers each time it was re-rendered.
Specifically, the line key={Shortid.generate()}
was the problem.