Make animated collapsible card component, with initial props to show or hide

Question

Background

Using React Native I was able to make collapsible card component. On Icon click the card slides up hiding its content, or expands showing its content. I would think setting the default value would be as easy as setting expanded to false or true, but I think the problem here is that when it is toggled an animation is triggered which changes the height of the card.

Example

class CardCollapsible extends Component{
  constructor(props){
    super(props);

    this.state = {
      title: props.title,
      expanded: true,
      animation: new Animated.Value(),
      iconExpand: "keyboard-arrow-down",
    };
  }

  _setMaxHeight(event){
      this.setState({
          maxHeight   : event.nativeEvent.layout.height
      });
  }

  _setMinHeight(event){
      this.setState({
          minHeight   : event.nativeEvent.layout.height
      });

      this.toggle = this.toggle.bind(this);
  }

  toggle(){
    let initialValue    = this.state.expanded? this.state.maxHeight + this.state.minHeight : this.state.minHeight,
        finalValue      = this.state.expanded? this.state.minHeight : this.state.maxHeight + this.state.minHeight;

    this.setState({
      expanded : !this.state.expanded
    });

    if (this.state.iconExpand === "keyboard-arrow-up") {
      this.setState({
        iconExpand : "keyboard-arrow-down"
      })
    } else {
      this.setState({
        iconExpand : "keyboard-arrow-up"
      })
    }
    this.state.animation.setValue(initialValue);
    Animated.spring( this.state.animation, {
        toValue: finalValue
      }
    ).start();
  }

  render(){

    return (
      <Animated.View style={[styles.container,{height: this.state.animation}]}>
          <View style={styles.titleContainer} onLayout={this._setMinHeight.bind(this)}>
            <CardTitle>{this.state.title}</CardTitle>
            <TouchableHighlight
              style={styles.button}
              onPress={this.toggle}
              underlayColor="#f1f1f1">
              <Icon
                name={this.state.iconExpand}
                style={{ fontSize: 30 }}/>
            </TouchableHighlight>
          </View>
          <Separator />
          <View style={styles.card} onLayout={this._setMaxHeight.bind(this)}>
            {this.props.children}
          </View>
      </Animated.View>
    );
  }
}

var styles = StyleSheet.create({
  container: {
    backgroundColor: '#fff',
    margin:10,
    overflow:'hidden'
    },
  titleContainer: {
    flexDirection: 'row'
    },
  card: {
    padding: 10
  }
});

export { CardCollapsible };

Open

Closed

Question

My goal is to allow a person calling the component to set the initial state of the component to expanded or open. But when I try changing the expanded state to false it does not render closed.

How would I go about allowing the user calling the component to select whether it is expanded or closed on initial component render?

Answer 1

Made a brand new one for you. Simple and works fine.

Note: no state required for this component. fewer state, better performance.

Maybe you could modify your own style on top of this =)

class Card extends Component {
    anime = {
        height: new Animated.Value(),
        expanded: false,
        contentHeight: 0,
    }

    constructor(props) {
        super(props);

        this._initContentHeight = this._initContentHeight.bind(this);
        this.toggle = this.toggle.bind(this);

        this.anime.expanded = props.expanded;
    }

    _initContentHeight(evt) {
        if (this.anime.contentHeight>0) return;
        this.anime.contentHeight = evt.nativeEvent.layout.height;
        this.anime.height.setValue(this.anime.expanded ? this._getMaxValue() : this._getMinValue() );
    }

    _getMaxValue() { return this.anime.contentHeight };
    _getMinValue() { return 0 };

    toggle() {
        Animated.timing(this.anime.height, {
            toValue: this.anime.expanded ? this._getMinValue() : this._getMaxValue(),
            duration: 300,
        }).start();
        this.anime.expanded = !this.anime.expanded;
    }

    render() {
        return (
            <View style={styles.titleContainer}>
                <View style={styles.title}>
                    <TouchableHighlight underlayColor="transparent" onPress={this.toggle}>
                        <Text>{this.props.title}</Text>
                    </TouchableHighlight>
                </View>

                <Animated.View style={[styles.content, { height: this.anime.height }]} onLayout={this._initContentHeight}>
                    {this.props.children}
                </Animated.View>
            </View>
        );
    }
}

Usage:

<Card title='Customized Card 1' expanded={false}>
    <Text>Hello, this is first line.</Text>
    <Text>Hello, this is second line.</Text>
    <Text>Hello, this is third line.</Text>
</Card>

Visual result: (only second card start with expanded={true}, others with expanded={false})