react-native-anchrable-scrollview

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A simple component that allow you to put anchors inside any children of a scrollview to directly go to its position.

• Each component accepts props of the initial react-native component
• Typescript support

Works for both Android & IOS

NOT WORKING IN WEB

View demo on snack.expo.io

Installation

If using yarn:

$ yarn add react-native-anchrable-scrollview

If using npm:

$ npm i react-native-anchrable-scrollview

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List of components

• AnchrableScrollView which is a component based on react-native Scrollview that calculates positions of Anchors inside and provide a goToAnchorfunction
• Anchorwhich is a component base on react-native View component
• HeaderAnchors which is a horizontal scrollview including buttons for each anchor inside the AnchrableScrollView

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Usage

import AnchrableScrollView, { Anchor } from 'react-native-anchrable-scrollview'

Wrap all your anchors component inside one top parent AnchrableScrollView component, and give a name to each anchor.

The AnchrableScrollView component will look for all Anchors components inside itself recursively. Then you can put an anchor whereever you want in the component tree, as long as the top parent is an AnchrableScrollView

Basic Usage

• Create a ref for the scrollView
• Create an array of refs for the anchors
• useCallback on the provided function goToAnchor

function App() {
  // Ref of the scrollView
  const ref = React.useRef();

  //Array representing anchors
  const anchorsRef = [
   {name: "#1", label: "My first section", ref: React.createRef()},
   {name: "#2", label: "Second veryyyyyyyy long section", ref: React.createRef()},
   {name: "#3", label: "Third section", ref: React.createRef()}
  ]

  const goToAnchor = React.useCallback(name => ref.current?.goToAnchor?.(name), [ref?.current])

  return (
    <View style={{marginTop: 50}}>
      <Button onPress={() => goToAnchor("#1")} title={anchorsRef[0].label}/>
      <Button onPress={() => goToAnchor("#2")} title={anchorsRef[1].label}/>
      <Button onPress={() => goToAnchor("#3")} title={anchorsRef[2].label}/>
      <AnchrableScrollView
        ref={ref}
      >
        <View>
         <Anchor name={anchorsRef[0].name} ref={anchorsRef[0].ref} style={{height: 1000, borderWidth: 1, borderColor: 'green'}}/>
         <Anchor name={anchorsRef[1].name} ref={anchorsRef[1].ref} style={{height: 1000, borderWidth: 1, borderColor: 'green'}}/>
         </View>
        <Anchor name={anchorsRef[2].name} ref={anchorsRef[2].ref} style={{height: 1000, borderWidth: 1, borderColor: 'green'}}/>
      </AnchrableScrollView>
    </View>
  );
}

Better Usage

• Map throw the anchorsRef array to make section with anchors.
• Use HeaderAnchors component to have as many buttons as anchors

import AnchrableScrollView, { Anchor, HeaderAnchors } from 'react-native-anchrable-scrollview'

function App() {
  const ref = React.useRef();
  const anchorsRef = [
   {name: "#1", label: "My first section", ref: React.createRef()},
   {name: "#2", label: "Second veryyyyyyyy long section", ref: React.createRef()}
  ]
  const anchor =  {name: "#3", label: "Third section", ref: React.createRef()}

  const goToAnchor = React.useCallback(name => ref.current?.goToAnchor?.(name), [ref?.current])

  return (
    <View style={{marginTop: 50}}>
    <HeaderAnchors 
      anchors={[...anchorsRef, anchor]}
      goToAnchor={goToAnchor}
    />
    <AnchrableScrollView
      ref={ref}
    >
      {
       anchorsRef.map((e, index) => (
          <View key={`${index}`}>
            <Anchor 
              ref={e.ref}
              name={e.name}
            >
              <Text>{e.label}</Text>
            </Anchor>
          <View style={{
            height: 700,
            borderWidth: 1,
            borderColor: 'red',
            justifyContent: 'space-between'
          }}>
            <Text>Here I am</Text>
            <Text>Here I am</Text>
          </View>
          </View>
        ))
      }
      <Anchor name={anchor.name} ref={anchor.ref} style={{height: 1000, borderWidth: 1, borderColor: 'green'}}/>
    </AnchrableScrollView>
    </View>
  );
}

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Documentation

AnchrableScrollView

PROPS

Name	Description	Details	Type
ref	Ref of the container: React.useRef()	required	React.RefObject
children	Children pass inside the scrollview	required	React.ReactNode

Accepts any props of the ScrollView Component of react-native

REF METHODS

Name	Description	Details
goToAnchor	function provided to move to a specific anchor specifying the name	params: anchorName

The ref contains the reference of the actual scrollView
You can access all method of standard ScrollView with ref?.current?._scrollView?.current.method

Anchor

PROPS

Name	Description	Details	Type
name	Name to identify the anchor	required	string
ref	Ref of the container: React.createRef()	required	React.RefObject
children	Children pass inside the view	not required	React.ReactNode

HeaderAnchors

PROPS

Name	Description	Details	Type
anchors	Array of anchors declared above	required	array
goToAnchor	callback to specify how to go to an anchor	required	Func
tagStyle	Button container style	optional	any
tagTextStyle	Style of the text inside a button	optional	any

Accepts any props of the ScrollView Component of react-native

useAnchorsMeasurements

This hook will provide you the set of measurements for Each anchors. It will return a Map with:

• key: the name of the anchor
• value: the measurement of that anchor (x, y, height, width)

Basic Usage

    const { children } = props
    const _scrollView = React.useRef<ScrollView>(null)
    const anchorsMeasurements = useAnchorsMeasurements(children, _scrollView, [])

PARAMS

Name	Description	Details	Type
children	The childrens you want to look for Anchors	required	React.ReactNode
parentContainer	The very top container which is the scrollView	required	React.RefObject
deps	dependencies to recalculates measurements when deps are changing	optional	any

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Contributing

Pull requests are always welcome! Feel free to open a new GitHub issue for any changes that can be made. Keep it simple. Keep it minimal. Don't put every single feature just because you can.

Working on your first Pull Request? You can learn how from this free series How to Contribute to an Open Source Project on GitHub

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Authors or Acknowledgments

• Vincent Riamon

License

This project is licensed under the MIT License