反应原生圆变换翻译动画

Question

嗨，我希望animated.view像圆圈一样移动。我用窦思考这个但是它不起作用。有人知道怎么做吗？我不想旋转视图。它应该在圆圈中移动。我是新来的本地人。如果有人可以帮助我会很好。

//import liraries
import React, { Component } from 'react';
import { View, Text, StyleSheet, Animated, Button, TouchableOpacity } from 'react-native';

// create a component
class MyClass extends Component {
  constructor() {
    super()
    this.animated = new Animated.Value(0);
  }

  animate() {    
    this.animated.setValue(0)
    Animated.timing(this.animated, {
      toValue: Math.PI *2,
      duration: 1000,
    }).start();
  }


  render() {
    const translateY = this.animated.interpolate({
      inputRange: [0, Math.PI *2],
      outputRange: [0, 200]
    });
    const translateX = translateY
    const transform = [{ translateY }, {translateX}];
    return (
      <View style={styles.container}>
        <Animated.View style={[{ transform }]}>
          <TouchableOpacity style={styles.btn}>
            <Text>hallo</Text>
          </TouchableOpacity>
        </Animated.View>
        <Button title="Test" onPress={() => { 
          this.animate() 
          }} />
      </View>
    );
  }
}

// define your styles
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#2c3e50',
  },
  btn: {
    backgroundColor: 'red',
    justifyContent: 'center',
    alignItems: 'center',
    width: 50,
  }
});

//make this component available to the app
export default MyClass;

Answer 1

您必须使用Trigonometric Function计算translateX和translateY。

translateX对应Math.sin()，translateY对应Math.cos()。

虽然 react-native animated.interpolate不支持函数回调，但您可以将其分为几个部分进行模拟（我在代码示例中选择了50个）：

完整代码：

export class App extends Component {
    constructor() {
        super()
        this.animated = new Animated.Value(0);

        var range = 1, snapshot = 50, radius = 100;
        /// translateX
        var inputRange = [], outputRange = [];
        for (var i=0; i<=snapshot; ++i) {
            var value = i/snapshot;
            var move = Math.sin(value * Math.PI * 2) * radius;
            inputRange.push(value);
            outputRange.push(move);
        }
        this.translateX = this.animated.interpolate({ inputRange, outputRange });

        /// translateY
        var inputRange = [], outputRange = [];
        for (var i=0; i<=snapshot; ++i) {
            var value = i/snapshot;
            var move = -Math.cos(value * Math.PI * 2) * radius;
            inputRange.push(value);
            outputRange.push(move);
        }
        this.translateY = this.animated.interpolate({ inputRange, outputRange });
    }

      animate() {
        this.animated.setValue(0)
        Animated.timing(this.animated, {
          toValue: 1,
          duration: 1000,
        }).start();
      }


      render() {
        const transform = [{ translateY: this.translateY }, {translateX: this.translateX}];
        return (
          <View style={styles.container}>
            <Animated.View style={[{ transform }]}>
              <TouchableOpacity style={styles.btn}>
                <Text>hallo</Text>
              </TouchableOpacity>
            </Animated.View>
            <Button title="Test" onPress={() => { 
              this.animate() 
              }} />
          </View>
        );
      }
    }

    // define your styles
    const styles = StyleSheet.create({
      container: {
        flex: 1,
        justifyContent: 'center',
        alignItems: 'center',
        backgroundColor: '#2c3e50',
      },
      btn: {
        backgroundColor: 'red',
        justifyContent: 'center',
        alignItems: 'center',
        width: 50,
      }
    });

结果：

Answer 2

如果，您正在寻找高性能的圆形旋转。 （无需发抖）（不再需要复杂的数学运算法则）

在这里

完整代码：

int main(void)
{

    char** pArr = 0;
    char string[] = "hello";

    pArr = (char**)malloc(sizeof(char) * 1); //make it an array with one element
    *pArr = (char*)malloc(sizeof(char) * (strlen(string) + 1)); //make it an array with the size of string
    strcpy(*pArr, string); //copy string to the first element of the array

    printf("%p", pArr); //the pointer where the heap corruption is detected

    free(pArr);

    getchar();
    return 0;
}

结果：

它将为您提供帮助。