@futurejj/react-native-visibility-sensor

🔍 Component visibility sensor wrapper to sense whether or not a component is in viewport with configurable inset thresholds & percent visibility callback.

Use Cases

• Lazy Loading: Load images/content only when visible to optimize performance in feeds, galleries, charts or webviews.
• Scroll Animations: Trigger animations (e.g., fade-ins, slides) for components entering the viewport.
• Analytics Tracking: Log impressions for ads/banners when visible for a set duration or percentage.
• Dynamic UI & Optimization: Pause/resume videos, cleanup out of screen components or timers based on component visibility in feeds or carousels.

Installation

Using yarn

yarn add @futurejj/react-native-visibility-sensor

using npm:

npm install @futurejj/react-native-visibility-sensor

Usage

import React, { useState } from 'react';
import { ScrollView, Text } from 'react-native';
import { VisibilitySensor } from '@futurejj/react-native-visibility-sensor';

export default function VisibilitySensorExample() {
  const [isVisible, setIsVisible] = useState(false);
  const [percentVisible, setPercentVisible] = useState<number>(0);

  return (
    <ScrollView>
      <VisibilitySensor
        onChange={setIsVisible}
        onPercentChange={setPercentVisible} // optional callback for % change
        threshold={{ top: 100, bottom: 100 }}
        style={[styles.item, { backgroundColor: isVisible ? 'green' : 'red' }]}>
          
        {/* Visibility state */}
        <Text>This View is currently visible? {isVisible ? 'yes' : 'no'}</Text>

        {/* Percent visibility state */}
        <Text>{`Percent visible: ${percentVisible}%`}</Text>
      </VisibilitySensor>
    </ScrollView>
  );
}

Properties

VisibilitySensorProps extends ViewProps from React Native, which includes common properties for all views, such as style, onLayout, etc.

Property	Type	Required	Description
onChange	(visible: boolean) => void	Yes	Callback function that fires when visibility changes.
onPercentChange	(percentVisible: number) => void	No	Callback function that fires when visibility % changes.
disabled	boolean	No	If true, disables the sensor.
triggerOnce	boolean	No	If true, the sensor will only trigger once.
delay	number or undefined	No	The delay in milliseconds before the sensor triggers.
threshold	VisibilitySensorThreshold	No	Defines the part of the view that must be visible for the sensor to trigger.

Additionally, all properties from ViewProps are also applicable.

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VisibilitySensorThreshold

Property	Type	Required	Description
top	number	No	The top threshold value for visibility.
bottom	number	No	The bottom threshold value for visibility.
left	number	No	The left threshold value for visibility.
right	number	No	The right threshold value for visibility.

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Notes

1. ⚠️ Facing problem on Android? Refer this discussion: #1 (comment)

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT

Support the project

                   

❤️ Thanks to

• Module built using create-react-native-library
• Forked & detached from: react-native-component-inview & @se09deluca/react-native-component-inview
• Pokemon image source: PokémonDB
• Readme is edited using Typora

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