如何检测用户在react native中放大还是缩小

Question

我正在开发react native应用程序，我想检测用户是放大还是缩小。

如果用户放大，我只想打印放大的用户，如果用户缩小，则打印缩小的用户

类似于下面的伪代码

const detectZoom = (event)=>{
if(event.gesture === "zoomed in"){
console.log("Zoomed in");
}

if(event.gesture === "zoomed out"){
console.log("Zoomed out");
}
}

//This is how I want to call it
<TouchableHighlight onPress={this.detectZoom}>
</TouchableHighlight>

请告诉我更好的方法。

Answer 1

您应该使用react原生手势处理程序，特别是在视图/容器中使用Pinch手势。

yarn add react-native-gesture-handler

https://docs.swmansion.com/react-native-gesture-handler/docs/api/gesture-handlers/pinch-gh

<PinchGestureHandler
onGestureEvent={this._onPinchGestureEvent}
onHandlerStateChange={this._onPinchHandlerStateChange}>
<View style={styles.container} collapsable={false}>
</View>
</PinchGestureHandler>

您的经办人：

let previousScale = 1;
_onPinchHandlerStateChange = (event) => {
if (event.nativeEvent.oldState === State.ACTIVE) {
//Handle Zoom here based on the values..
let newScale = previousScale * event.nativeEvent.scale;
if(newScale > previousZoom){
console.log("zoomed in");
}else{
console.log("zoomed out");
}
}
};