In React Native, how can I get the Y offset of a custom component and then scroll a ScrollView to its position?

问题

In React Native, I have a screen with a ScrollView:

let scrollView;
let myComponent2;

function onPress() {
  myComponent2.measure((frameOffsetX, frameOffsetY, width, height, pageOffsetX, pageOffsetY) => {
  scrollView.scrollTo({ y: frameOffsetY });
}

function MyScrollView() {
  return (
    <ScrollView ref={ref => scrollView = ref}>
      <MyButton onPress={onPress} />
      <MyComponent1 />
      <MyComponent2 ref={ref => myComponent2 = ref} />
      <MyComponent3 />
    </ScrollView>
  );
};

And MyButton is defined like this:

function MyButton(props) {
  return (
    <TouchableHighlight onPress={props.onPress}>
      <Text>Press Me</Text>
    </TouchableHighlight>
  );
}

What I'm trying to accomplish is that when the user presses on the MyButton component, the ScrollView should scroll so that MyComponent2 is visible. The problem is that I can't use measure on a custom component, only directly in a View.

So my question is: what would be the best approach to get the Y offset of a custom React Native component?

回答1:

I ended up wrapping my component around an extra View to be able to get its offset:

let scrollView;
let myComponent2Wrapper;

function onPress() {
  myComponent2Wrapper.measure((frameOffsetX, frameOffsetY, width, height, pageOffsetX, pageOffsetY) => {
  scrollView.scrollTo({ y: frameOffsetY });
}

function MyScrollView() {
  return (
    <ScrollView ref={ref => scrollView = ref}>
      <MyButton onPress={onPress} />
      <MyComponent1 />
      <View ref={ref => myComponent2Wrapper = ref}>
        <MyComponent2 />
      </View>
      <MyComponent3 />
    </ScrollView>
  );
};

来源：https://stackoverflow.com/questions/37450468/in-react-native-how-can-i-get-the-y-offset-of-a-custom-component-and-then-scrol

标签

javascript

uiscrollview

react-native

scrollview