If I have an imported component called <Draggable />
in react-native,
How do I call a custom function in the parent component when onPanResponderGrant
decides the gesture has started?
You'll see I'm passing an id
of 'A'
and 'B'
into <Draggable />
, and I'd like to be able to call them back out on touch, and display them in the infoBox
at the bottom of the main View
?
// App
import React, { Component } from 'react';
import { View, Text, } from 'react-native';
import styles from './cust/styles';
import Draggable from './cust/draggable';
export default class Viewport extends Component {
constructor(props){
super(props);
this.state = {
dID : null,
};
}
render(){
return (
<View style={styles.mainContainer}>
<View style={styles.draggableContainer}>
<Text>Draggable Container</Text>
<Draggable id='A' />
<Draggable id='B' />
</View>
<View style={styles.infoBar}>{this.infoBarData()}</View>
</View>
);
}
infoBarData(){
if (this.state.dID) {
return(
<Text>{this.state.dID}</Text>
)
}
}
}
and
// Draggable
import React, { Component } from 'react';
import { Text, PanResponder, Animated, } from 'react-native';
import styles from './styles';
class Draggable extends Component {
constructor(props) {
super(props);
this.state = {
pan : new Animated.ValueXY(),
};
this.panResponder = PanResponder.create({
onStartShouldSetPanResponder : () => true,
onPanResponderMove : Animated.event([null,{
dx : this.state.pan.x,
dy : this.state.pan.y,
}]),
onPanResponderRelease : () => {
Animated.spring(this.state.pan,{toValue:{x:0, y:0}}).start();
}
});
}
render() {
return (
<Animated.View
{...this.panResponder.panHandlers}
style={[this.state.pan.getLayout(), styles.circleAlt, styles.position]}>
<Text style={styles.textAlt}>Drag me!</Text>
<Text style={styles.textNum}>{this.props.id}</Text>
</Animated.View>
)
}
}
export default Draggable;
EDIT
I've added the following to the parent class
// Object
<Draggable
onPanResponderMove={this.onStopMove}
onPanResponderRelease={this.onMove}
id='A' />
// Methods
onMove = (dID) => {
this.setState({ dID });
}
onStopMove = () => {
this.setState({ dID: null });
}
And I added the following to the Draggable
class.
// Methods
_handleOnPanResponderMove(evt, gestureState) {
Animated.event([null,{
// These animate movement on the X/Y axis
dx : this.state.pan.x,
dy : this.state.pan.y,
}]);
this.props.onPanResponderRelease(this.props.id);
}
But when I move the animated event out of the PanResponder.create({})
by doing the following, it loses it's ability to be dragged. I assume this is something to do with
PanResponder.create({
...,
onPanResponder : this._handleOnPanResponder.bind(this),
...,
})
Not being returned a value?
EDIT 2
I also tried to add the following, but again, didn't work.
PanResponder.create({
...,
onPanResponder : (evt ,gesture) => {
Animated.event([null,{
// These animate movement on the X/Y axis
dx : this.state.pan.x,
dy : this.state.pan.y,
}]);
this.props.onPanResponderRelease(this.props.id);
}
...,
})
You need to pass a callback handler with Draggable component, like
<Draggable id="A" gestureHandler={(data) => {
/*
do whatever you want to do with the data, like store it into state
*/
}}
In your Draggable component, call this handler as per your requirement (when it is decided that gesture has started), like
if (this.props.gestureHandler instanceof Function) {
this.props.gestureHandler.call(this, this.props.id);
}
Ok,
So here is the code that works for anybody who may come across this question.
// App
import React, { Component } from 'react';
import {
View,
Text,
} from 'react-native';
import styles from './cust/styles';
import Draggable from './cust/draggable';
export default class Viewport extends Component {
constructor(props){
super(props);
this.state = {
dID : null,
};
}
render(){
return (
<View style={styles.mainContainer}>
<View style={styles.draggableContainer}>
<Text>Draggable Container</Text>
<Draggable
onPanResponderGrant={this.onMove}
onPanResponderRelease={this.onStopMove}
id='A' />
<Draggable
onPanResponderGrant={this.onMove}
onPanResponderRelease={this.onStopMove}
id='B' />
</View>
<View style={styles.infoBar}>{this.printInfo()}</View>
</View>
);
}
onMove = (dID) => {
this.setState({ dID });
}
onStopMove = () => {
this.setState({ dID: null });
}
printInfo(){
if (this.state.dID) {
return(
<Text>{this.state.dID}</Text>
);
}
}
}
// Draggable
import React, { Component } from 'react';
import {
Text,
PanResponder,
Animated,
} from 'react-native';
import styles from './styles';
class Draggable extends Component {
constructor(props) {
super(props);
this.state = {
pan : new Animated.ValueXY(),
};
this.panResponder = PanResponder.create({
onStartShouldSetPanResponder : () => true,
onPanResponderGrant : () => {
this.props.onPanResponderGrant(this.props.id)
},
onPanResponderMove : Animated.event([null,{
dx : this.state.pan.x,
dy : this.state.pan.y,
}]),
onPanResponderRelease : () => {
Animated.spring(
this.state.pan,
{toValue:{x:0, y:0}}
).start();
this.props.onPanResponderRelease();
},
});
}
render() {
return (
<Animated.View
{...this.panResponder.panHandlers}
style={[this.state.pan.getLayout(), styles.circleAlt, styles.position]}>
<Text style={styles.textAlt}>Drag me!</Text>
<Text style={styles.textNum}>{this.props.id}</Text>
</Animated.View>
)
}
}
export default Draggable;
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