在 React Native 中构建流畅的、键盘感知的登录屏幕-js教程-PHP中文网

Building a Smooth, Keyboard-Aware Sign-In Screen in React Native

在 React Native 中创建一个优化良好的登录屏幕通常涉及处理键盘交互，以避免输入字段被键盘隐藏。在本指南中，我们将逐步构建一个具有动画调整功能的键盘感知登录屏幕，利用自定义挂钩来管理键盘偏移高度。我们还将添加标题图像并组织屏幕以获得美观且实用的布局。

该实现的特点：

键盘感知：屏幕根据键盘高度调整其位置。
平滑动画：键盘出现或消失时的动画过渡。
可重复使用的自定义挂钩：动态管理键盘高度的 useKeyboardOffsetHeight 挂钩。

1.自定义Hook：useKeyboardOffsetHeight

自定义钩子 useKeyboardOffsetHeight 侦听键盘显示/隐藏事件并返回键盘高度，这对于动画布局调整至关重要。此挂钩还确保该功能在 iOS 和 Android 上都能正常工作。

import { useEffect, useState } from 'react';
import { Keyboard } from 'react-native';

export default function useKeyboardOffsetHeight() {
  const [keyboardOffsetHeight, setKeyboardOffsetHeight] = useState(0);

  useEffect(() => {
    const showListener = Keyboard.addListener('keyboardWillShow', (e) => {
      setKeyboardOffsetHeight(e.endCoordinates.height);
    });
    const hideListener = Keyboard.addListener('keyboardWillHide', () => {
      setKeyboardOffsetHeight(0);
    });

    const androidShowListener = Keyboard.addListener('keyboardDidShow', (e) => {
      setKeyboardOffsetHeight(e.endCoordinates.height);
    });
    const androidHideListener = Keyboard.addListener('keyboardDidHide', () => {
      setKeyboardOffsetHeight(0);
    });

    return () => {
      showListener.remove();
      hideListener.remove();
      androidShowListener.remove();
      androidHideListener.remove();
    };
  }, []);

  return keyboardOffsetHeight;
}

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2. 主要组件：应用程序

主要组件使用自定义 useKeyboardOffsetHeight 挂钩和动画 API 来管理登录表单的平滑过渡。该表单包括电子邮件和密码字段、登录按钮和标题图像。

import React, { useEffect, useRef, useState } from 'react';
import { Animated, Image, StyleSheet, Text, TextInput, TouchableOpacity, View } from 'react-native';
import useKeyboardOffsetHeight from './useKeyboardOffsetHeight';

const App = () => {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const keyboardOffsetHeight = useKeyboardOffsetHeight();
  const animatedValue = useRef(new Animated.Value(0)).current;

  const handleSignIn = () => {
    // Handle sign-in logic here
    console.log('Email:', email);
    console.log('Password:', password);
  };

  // Animate view based on keyboard height
  useEffect(() => {
    Animated.timing(animatedValue, {
      toValue: keyboardOffsetHeight ? -keyboardOffsetHeight * 0.5 : 0, // adjust "0.5" as per requirement to adjust scroll position
      duration: 500,
      useNativeDriver: true,
    }).start();
  }, [keyboardOffsetHeight]);

  return (
    <View style={styles.container}>
      <View style={{ flex: 1 }}>
        <Image
          source={{
            uri: 'https://cdn.shopaccino.com/igmguru/articles/Become-React-Native-Developer.png?v=496',
          }}
          style={styles.image}
          resizeMode="cover"
        />
      </View>
      <Animated.ScrollView
        bounces={false}
        keyboardShouldPersistTaps="handled"
        keyboardDismissMode="on-drag"
        style={{ transform: [{ translateY: animatedValue }] }}
        contentContainerStyle={styles.box}
      >
        <Text style={styles.title}>Sign In</Text>
        <TextInput
          style={styles.input}
          placeholder="Email"
          value={email}
          onChangeText={setEmail}
          keyboardType="email-address"
          autoCapitalize="none"
        />
        <TextInput
          style={styles.input}
          placeholder="Password"
          value={password}
          onChangeText={setPassword}
          secureTextEntry
        />
      </Animated.ScrollView>
      <TouchableOpacity style={styles.signInButton} onPress={handleSignIn}>
        <Text style={styles.buttonText}>Sign In</Text>
      </TouchableOpacity>
    </View>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    padding: 20,
    backgroundColor: '#f9f9f9',
  },
  image: {
    flex: 1,
    borderRadius: 10,
  },
  box: {
    flex: 1,
    width: '100%',
    backgroundColor: 'lightblue',
    padding: 20,
    borderRadius: 10,
  },
  title: {
    fontSize: 24,
    fontWeight: 'bold',
    textAlign: 'center',
    marginBottom: 20,
  },
  input: {
    height: 50,
    borderColor: '#ddd',
    borderWidth: 1,
    borderRadius: 8,
    paddingHorizontal: 10,
    marginBottom: 15,
    fontSize: 16,
    backgroundColor: '#f9f9f9',
  },
  signInButton: {
    width: '100%',
    marginTop: 20,
    backgroundColor: '#4a90e2',
    borderRadius: 8,
    paddingVertical: 15,
    alignItems: 'center',
    marginBottom: 40,
  },
  buttonText: {
    color: '#fff',
    fontSize: 18,
    fontWeight: 'bold',
  },
});

export default App;

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