在我的 React Native 应用程序的标题中，我有一个条件图标和一个 Searchbar .

static navigationOptions = ({ navigation }) => {
const { params = {} } = navigation.state;
return {
  headerTitle: (
    <View
      style={{
        flex: 1,
        backgroundColor: Platform.OS === 'ios' ? '#e54b4d' : '',
        alignItems: 'center',
        flexDirection: 'row',
        paddingHorizontal: 10,
        height: StatusBar.currentHeight,
      }}>
      {params.isIconTriggered && <Icon name="chevron-left" size={28} />}
      <SearchBar
        round
        platform={'default'}
        placeholder="Search"
        containerStyle={{
          flex: 1,
          backgroundColor: 'transparent',
        }}
      />
    </View>
  ),
  headerStyle: {
    backgroundColor: '#e54b4d',
  },
};
};

通常，搜索栏会占据标题的整个宽度，这正是我想要的。如果条件 isIconTriggered 为真，一个图标将出现在 Searchbar 前面，SearchBar 的宽度将收缩到足以使图标在它旁边可见。

但是，发生这种情况时没有过渡或动画，而且感觉和看起来都不好。我想向搜索栏添加一个动画，以便在触发条件并出现图标时宽度逐渐平滑地缩小。

这有可能实现吗？我该如何实现？

最佳答案

尝试学习React Native的Animated API。

这是我用按钮触发器完成的。

import React, {Component} from 'react';
import {StyleSheet, View, TextInput , Button, SafeAreaView, Animated} from 'react-native';
import FA from 'react-native-vector-icons/FontAwesome5'

const AnimatedIcon = Animated.createAnimatedComponent(FA)
// make your icon animatable using createAnimatedComponent method

export default class Application extends Component {

  animVal = new Animated.Value(0);
   // initialize animated value to use for animation, whereas initial value is zero

  interpolateIcon = this.animVal.interpolate({inputRange:[0,1], outputRange:[0,1]})
  interpolateBar = this.animVal.interpolate({inputRange:[0,1],outputRange:['100%','90%']})
  // initialize interpolation to control the output value that will be passed on styles
  // since we will animate both search bar and icon. we need to initialize both 
  // on icon we will animate the scale whereas outputRange starts at 0 end in 1
  // on search bar we will animate width. whereas outputRange starts at 100% end in 90%

  animatedTransition = Animated.spring(this.animVal,{toValue:1})
  // we use spring to make the animation bouncy . and it will animate to Value 1

  clickAnimate = () => {
    this.animatedTransition.start()
  }
  // button trigger for animation

  //Components that will use on Animation must be Animated eg. Animted.View
  render() {
    return (
      <SafeAreaView>
      <View style={styles.container}>
        <View style={styles.search}>
        {/* our icon */}

        <Animated.View style={{width: this.interpolateBar}}>
        <TextInput placeholder='search here' style={styles.input}/>
        </Animated.View>

        <AnimatedIcon name='search' size={28} style={{paddingLeft: 10,paddingRight:10, transform:[{scale: this.interpolateIcon}]}}/>
        </View>

          <Button title='animate icon' onPress={this.clickAnimate}/>
      </View>
      </SafeAreaView>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    backgroundColor:'#F79D42',
    // flex: 1,
    height:'100%',
    paddingTop:20,
    flexDirection: 'column',
    // justifyContent: 'center',
    alignItems:'center'
  },
  input:{
    width: '100%',
    height:40,
    backgroundColor:'gray',
    textAlign:'center'
  },
  search:{
    flexDirection:'row-reverse',
    width:'90%',
    height:40,
    alignItems:'center'
  }
});

使用 react-native-elements SearchBar 组件的解决方案。 将 SearchBar 组件包装在 Animated.View 中。 明确地为搜索栏设置动画

像这样:

 <Animated.View style={{width: this.interpolateBar}}>
    <SearchBar
    placeholder="Type Here..."
    containerStyle={{width: '100%'}}
  />
    </Animated.View>

关于javascript - React Native - 动画宽度收缩，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55124009/