CODEWITHSUNDEEP
javascriptreactjsanimationreact-nativedraggable
ronnyrr
ronnyrr

Reputation: 1561

React Native Animated PanResponder reverse on second input

I got a component using the PanResponder in combination with Animated from React Native API's. The code of my component:

import React, { Component } from 'react';
import { Animated, PanResponder } from 'react-native';

import { SVG } from '../';
import { Icon, LockContainer, StatusCircle } from './styled';

class VehicleLock extends Component {
  state = {
    pan: new Animated.ValueXY({ x: 9, y: 16 }),
  };

  componentWillMount() {
    this.animatedValueY = 0;

    this.minYValue = 16;
    this.maxYValue = 175;

    this.state.pan.y.addListener((value) => {
      this.animatedValueY = value.value;
    });

    this.panResponder = PanResponder.create({
      onStartShouldSetPanResponderCapture: () => true,
      onMoveShouldSetPanResponderCapture: () => true,

      onPanResponderGrant: (evt, gestureState) => {
        this.state.pan.setOffset({ x: 0, y: 0 });
        // this.state.pan.setOffset(this.state.pan.__getValue());
        this.state.pan.setValue({ x: 9, y: this.minYValue });
      },
      onPanResponderMove: (evt, gestureState) => {
        // deltaY: amount of pixels moved vertically since the beginning of the gesture
        let newY = gestureState.dy;

        if (newY < this.minYValue) {
          newY = this.minYValue;
        } else if (newY > this.maxYValue) {
          newY = this.maxYValue;
        }

        Animated.event([null, {
          dy: this.state.pan.y,
        }])(evt, {
          dy: newY,
        });
      },
      onPanResponderRelease: (evt, gestureState) => {
        let newY = this.minYValue;
        const releaseY = gestureState.dy;

        if (releaseY > 83) {
          newY = this.maxYValue;
        }

        Animated.spring(this.state.pan, {
          toValue: {
            x: 9,
            y: newY,
          },
        }).start();
      },
    });
  }

  componentWillUnmount() {
    this.state.pan.x.removeAllListeners();
    this.state.pan.y.removeAllListeners();
  }

  render() {
    const customStyles = {
      ...this.state.pan.getLayout(),
      position: 'absolute',
      zIndex: 10,
      transform: [
        {
          rotate: this.state.pan.y.interpolate({
            inputRange: [this.minYValue, this.maxYValue],
            outputRange: ['0deg', '180deg'],
          }),
        },
      ],
    };

    return (
      <LockContainer>
        <SVG icon="lock_open" width={16} height={21} />

        <Animated.View
          {...this.panResponder.panHandlers}
          style={customStyles}
        >
          <StatusCircle>
            <Icon>
              <SVG icon="arrow_down" width={23} height={23} />
            </Icon>
          </StatusCircle>
        </Animated.View>

        <SVG icon="lock_closed" width={16} height={21} />
      </LockContainer>
    );
  }
}

export default VehicleLock;

As you can see in my code I animate the Y value with a boundary. It has to stay in a box between certain values. As soon users release the drag and it's over half of the max Y value it's animated to the max value.

This works without any problems, but on the second interaction I would like to reverse the action. So instead of going down, it has to go up. Unfortunately on release the Y value resets.

As you can see in the comment in my code I know the movement is based on the delta, so the moved Y value since the interaction started. This is explained in this great comment PanResponder snaps Animated.View back to original position on second drag.

Although I don't know how to fix it. Here you can see my current behaviour: enter image description here

On the second input the element snap back to the top. Which is expected behavior. As @jevakallio states in his comment, you can reset the values in the offset in onPanResponderGrant. As I do that (commented out), the element resets the values, but on second interaction it will animate outside the container. So in that case 0 is the maxYValue and it animates 175 outside the container to the bottom.

How can I make a reversed animated outside back to the top? I don't seem to get this. Thanks in advance!

Upvotes: 0

Views: 1785

Answers (1)

Guido Baars
Guido Baars

Reputation: 11

According to Panresponder docs the onPanResponderGrant should indicate the start of a gesture. So if you set the this.state.pan.setOffset and the this.state.pan.setValue at this point, it will reset with the start of every gesture. Try a console.log in the onPanResponderGrant and see what happens.

Also, a parent or wrapping component implementing the PanResponder could be interfering with your PanResponder. This could be another good starting point to troubleshoot.

From the PanResponder docs:

onPanResponderGrant: (evt, gestureState) => {
    // The gesture has started. Show visual feedback so the user knows
    // what is happening!

    // gestureState.d{x,y} will be set to zero now
  },

Upvotes: 1

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