Explaining how modal windows work in React Native-JS Tutorial-php.cn

Explaining how modal windows work in React Native

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Release： 2023-08-24 15:01:01

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Modal components help to display content views above UI content.

The basic modal components are as follows-

<Modal animationType="slide" transparent={true} visible={modalVisible} onRequestClose={() => { Alert.alert("Modal has been closed."); }}> Your Content Here</Modal>

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To use the modal component, you need to import it first, as shown below-

import { Modal } from "react-native";

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The basic properties of the modal window are as follows-

Sr.No	Props and instructions
1	< strong>animationType This property handles the displayed animation Modal window. It is an enumeration with three values − Slide, Fade and None.
2	onDismiss This property accepts a function that will be called When the modal window is closed.
3	onOrientationChange Callback function called when the device starts When a modal window changes orientation show.
4	onShow The function passed as the prop value is called When showing a modal window.
5	presentationStyle This property handles the display of the modal box window. Available values are full screen, pageSheet, formSheet and overFullScreen.
6	Transparent This prop will determine whether to provide a transparent view or fill The entire view of the modal window.
7	visibile < p>This property will determine whether your modal window is Visible or invisible.

Example 1: Show modal window display

To use a modal component, you need to import it first as shown below -

import { Modal } from "react-native";

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To display a modal window, you can decide the animation to be displayed on it. Options are Slide, Fade, and None. In the following example, we want to display a simple modal window with text and buttons as shown below -

<Modal
      animationType="slide"
      transparent={true}
      visible={isVisible}
   >
   <View style={styles.centeredView}>
      <View style={styles.myModal}>
         <Text style={styles.modalText}>Modal Window Testing!</Text>
            <Button style={styles.modalButton} title="Close" onPress={() => {setModalVisiblility(false); }}/>
      </View>
   </View>
</Modal>

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isVisible variable is assigned to the visible property. Defaults to false, i.e. modal windows will not be shown by default. The isVisible property is initialized as follows -

const [isVisible, setModalVisiblility] = useState(false);

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setModalVisiblility will update the isVisible variable from false to true and vice versa.

The close button defined in the component calls setModalVisiblility(false), which will make isVisible false and the modal window will disappear.

To show a modal window, have a button outside the component calling setModalVisiblility(true) as shown below -

<View style={styles.centeredView}>
   <Modal
      animationType="slide"
      transparent={true}
      visible={isVisible}
   >
   <View style={styles.centeredView}>
      <View style={styles.myModal}>
         <Text style={styles.modalText}>Modal Window Testing!</Text>
            <Button style={styles.modalButton} title="Close" onPress={() =>{setModalVisiblility(false); }}/>
            </View>
         </View>
      </Modal>
      <Button title="Click Me" onPress={() => {
         setModalVisiblility(true);
      }}
   />
</View>

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This is the working code to show/hide the modal window.

import React, { useState } from "react";
import { Button, Alert, Modal, StyleSheet, Text, View } from "react-native";
const App = () => {
   const [isVisible, setModalVisiblility] = useState(false);
   return (
      <View style={styles.centeredView}>
         <Modal
            animationType="slide"
            transparent={true}
            visible={isVisible}
         >
         <View style={styles.centeredView}>
            <View style={styles.myModal}>
               <Text style={styles.modalText}>Modal Window Testing!</Text>
                  <Button style={styles.modalButton} title="Close" onPress={() =>{setModalVisiblility(false); }}/>
                  </View>
               </View>
            </Modal>
            <Button title="Click Me" onPress={() => {
               setModalVisiblility(true);
            }}
         />
      </View>
   );
};
const styles = StyleSheet.create({
   centeredView: {
      flex: 1,
      justifyContent: "center",
      alignItems: "center",
      marginTop: 22
   },
   myModal: {
      width:200,
      height:200,
      margin: 20,
      backgroundColor: "white",
      borderRadius: 20,
      padding: 35,
      alignItems: "center",
      shadowColor: "#000",
      shadowOffset: {
         width: 0,
         height: 2
      },
      shadowOpacity: 0.30,
      shadowRadius: 4,
      elevation: 5
   },
   modalText: {
      marginBottom: 20,
      textAlign: "center"
   },
   modalButton: {
      marginBottom: 50,
   }
});
export default App;

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Output

解释 React Native 中模态窗口的工作原理

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