使用 react-native-maps 在 ReactNative 中获取当前位置、纬度和经度 [英] Get current location, latitude and longitude in ReactNative using react-native-maps
问题描述
我正在开发地图位置.当我点击某个特定的地方时,我会得到纬度和经度,但不是当前的位置、纬度和经度.
I am developing a map location. When I click in some particular place I get the latitude and longitude, but not the current location, latitude and longitude.
我不知道如何找到.
我怎样才能得到它们,我怎样才能把标记放在那个位置?
How can I get them and how can I put the marker at that position?
这是我的代码:
class Maps extends React.Component {
constructor(props) {
super(props);
this.state = {
region: {
latitude: LATITUDE,
longitude: LONGITUDE,
latitudeDelta: LATITUDE_DELTA,
longitudeDelta: LONGITUDE_DELTA,
},
marker: {
latlng:{
latitude: null,
longitude: null,
latitudeDelta: LATITUDE_DELTA,
longitudeDelta: LONGITUDE_DELTA
}
}
}
}
componentDidMount() {
navigator.geolocation.getCurrentPosition (
(position) => { alert("value:" + position) },
(error) => { console.log(error) },
{
enableHighAccuracy: true,
timeout: 20000,
maximumAge: 10000
}
)
}
onMapPress(e) {
alert("coordinates:" + JSON.stringify(e.nativeEvent.coordinate))
this.setState({
marker: [{ coordinate: e.nativeEvent.coordinate }]
})
}
render() {
return (
<View style={styles.container}>
<View style={{flexGrow:1}}>
<MapView
ref="map"
provider={this.props.provider}
style={styles.map}
onPress={this.onMapPress.bind(this)}
provider = {PROVIDER_DEFAULT}
mapType="standard"
zoomEnabled={true}
pitchEnabled={true}
showsUserLocation={true}
followsUserLocation={true}
showsCompass={true}
showsBuildings={true}
showsTraffic={true}
showsIndoors={true}>
</MapView>
</View>
</View>
)
}
}
推荐答案
我按照这些步骤使用 react-native@0.42.3
和 react-native-maps@^0.13.1
并在日期使用 react-native@0.44.0
和 react-native-maps@^0.15.2
:
I did it following these steps using react-native@0.42.3
and react-native-maps@^0.13.1
and using react-native@0.44.0
and react-native-maps@^0.15.2
at the date:
在state
中设置一个mapRegion
对象,最后一个longitude
和最后一个latitude
为空
:
Set a mapRegion
object in the state
, the last longitude
and the last latitude
as null
:
state = {
mapRegion: null,
lastLat: null,
lastLong: null,
}
然后在您的 componentDidMount()
函数中观察当前位置的每个变化:
Then within your componentDidMount()
function watch for each change in the current position:
componentDidMount() {
this.watchID = navigator.geolocation.watchPosition((position) => {
...
});
}
当你的 this.state.mapRegion
有变化时更新它们,传递实际坐标和 delta
值(我的可能与你的不同,所以调整它们):
When there are changes update them in your this.state.mapRegion
, passing the actual coords and the delta
values (mine can be different to yours, so adapt them):
componentDidMount() {
this.watchID = navigator.geolocation.watchPosition((position) => {
// Create the object to update this.state.mapRegion through the onRegionChange function
let region = {
latitude: position.coords.latitude,
longitude: position.coords.longitude,
latitudeDelta: 0.00922*1.5,
longitudeDelta: 0.00421*1.5
}
this.onRegionChange(region, region.latitude, region.longitude);
}, (error)=>console.log(error));
}
然后您需要 onRegionChange()
函数,该函数用于为 componentDidMount()
函数中的元素设置"新值:
Then you need the onRegionChange()
function, that's being used to "set" new values to your elements within the componentDidMount()
function:
onRegionChange(region, lastLat, lastLong) {
this.setState({
mapRegion: region,
// If there are no new values set the current ones
lastLat: lastLat || this.state.lastLat,
lastLong: lastLong || this.state.lastLong
});
}
在 componentWillUnmount()
上卸载地理位置:
Unmount the geolocation on componentWillUnmount()
:
componentWillUnmount() {
navigator.geolocation.clearWatch(this.watchID);
}
并渲染 MapView
传递您当前的 mapRegion
对象,其中的 MapView.Marker
只是为了向您显示当前的 >latitude
和 longitude
当它们改变时:
And render the MapView
passing your current mapRegion
object, the MapView.Marker
inside of it is just to show you the current latitude
and longitude
when they change:
render() {
return (
<View style={{flex: 1}}>
<MapView
style={styles.map}
region={this.state.mapRegion}
showsUserLocation={true}
followUserLocation={true}
onRegionChange={this.onRegionChange.bind(this)}>
<MapView.Marker
coordinate={{
latitude: (this.state.lastLat + 0.00050) || -36.82339,
longitude: (this.state.lastLong + 0.00050) || -73.03569,
}}>
<View>
<Text style={{color: '#000'}}>
{ this.state.lastLong } / { this.state.lastLat }
</Text>
</View>
</MapView.Marker>
</MapView>
</View>
);
}
添加 StyleSheet.absoluteFillObject您的地图,以便使用设备的整个宽度和高度正确呈现它.
Add the StyleSheet.absoluteFillObject for your map in order to render it properly using the whole width and height of your device.
const styles = StyleSheet.create({
map: {
...StyleSheet.absoluteFillObject,
}
});
因此,对于您的 onPress()
函数,您可以执行类似于 onRegionChange()
的操作,即获取实际坐标并设置它们:
So for your onPress()
function you could do something similar to the onRegionChange()
, that's to get the actual coordinates and to set them:
onMapPress(e) {
let region = {
latitude: e.nativeEvent.coordinate.latitude,
longitude: e.nativeEvent.coordinate.longitude,
latitudeDelta: 0.00922*1.5,
longitudeDelta: 0.00421*1.5
}
this.onRegionChange(region, region.latitude, region.longitude);
}
查看 expo.io 上的完整代码(尽管 react-native-maps代码>未安装)
Check the full code on expo.io (although react-native-maps
isn't installed)
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