@openspacelabs/react-native-zoomable-view

A view component for react-native with pinch to zoom, tap to move and double tap to zoom capability. You can zoom everything, from normal images, text and more complex nested views.

This library is a fork of @dudigital/react-native-zoomable-view. We've rewritten most of the logic in the original library to address the following items:

What sets this library apart from the other zoom-pan libraries?

This library offers a much better user experience than the others:

The ability to zoom and pan at the same time.
No jittering during zooming.
Zoom center correctly placed at the pinch center - currently this is the ONLY react-native library that offers this.
And many other goodies. Check out the documentation below for more details.

M1 Mac iOS Simulator

Note that if try to run this library on an M1 Mac iOS Simulator, the animations will be quite jittery/jumpy. Test it on a real physical device or non-M1 Mac to see the actual performance.

Demo

Want to run the library on your physical device right here right now? Check out this Expo Snack

Installation

We are working with the original maintainers of this library to transfer the NPM alias for react-native-zoomable-view. In the meantime, you will want to use @openspacelabs/react-native-zoomable-view as the package identifier.

To add this package, run

npm add @openspacelabs/react-native-zoomable-view

or

yarn add @openspacelabs/react-native-zoomable-view

Basic Usage

This component is based on react-natives View, enhanced by panresponders and other events to make it zoomable. Therefore no platform specific configuration needs to be done.

Just use it as a drop in component instead of a normal view.

Import ReactNativeZoomableView:

import { ReactNativeZoomableView } from '@openspacelabs/react-native-zoomable-view';

Use the component:

<ReactNativeZoomableView
   maxZoom={1.5}
   minZoom={0.5}
   zoomStep={0.5}
   initialZoom={1}
   bindToBorders={true}
   onZoomAfter={this.logOutZoomState}
   style={{
      padding: 10,
      backgroundColor: 'red',
   }}
>
   <Text>This is the content</Text>
</ReactNativeZoomableView>

Example

Here is a full drop in example you can use in Expo, after installing the package.

import * as React from 'react';

import { StyleSheet, View, Text, Image } from 'react-native';
import { ReactNativeZoomableView } from '@openspacelabs/react-native-zoomable-view';

export default function App() {
  return (
    <View style={styles.container}>
      <Text>ReactNativeZoomableView</Text>
      <View style={{ borderWidth: 5, flexShrink: 1, height: 500, width: 310 }}>
        <ReactNativeZoomableView
          maxZoom={30}
          // Give these to the zoomable view so it can apply the boundaries around the actual content.
          // Need to make sure the content is actually centered and the width and height are
          // dimensions when it's rendered naturally. Not the intrinsic size.
          // For example, an image with an intrinsic size of 400x200 will be rendered as 300x150 in this case.
          // Therefore, we'll feed the zoomable view the 300x150 size.
          contentWidth={300}
          contentHeight={150}
        >
          <Image
            style={{ width: '100%', height: '100%', resizeMode: 'contain' }}
            source={{ uri: 'https://via.placeholder.com/400x200.png' }}
          />
        </ReactNativeZoomableView>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
    padding: 20,
  },
  box: {
    width: 60,
    height: 60,
    marginVertical: 20,
  },
});

Props

Options

These options can be used to limit and change the zoom behavior.

name	type	description	default
zoomEnabled	boolean	Can be used to enable or disable the zooming dynamically	true
initialZoom	number	Initial zoom level on startup	1.0
maxZoom	number	Maximum possible zoom level (zoom in). Can be set to `null` to allow unlimited zooming	1.5
minZoom	number	Minimum possible zoom level (zoom out)	0.5
disablePanOnInitialZoom	boolean	If true, panning is disabled when zoom level is equal to the initial zoom level	false
doubleTapDelay	number	How much delay will still be recognized as double press (ms)	300
doubleTapZoomToCenter	boolean	If true, double tapping will always zoom to center of View instead of the direction it was double tapped in
bindToBorders	boolean	If true, it makes sure the object stays within box borders	true
zoomStep	number	How much zoom should be applied on double tap	0.5
pinchToZoomInSensitivity	number	the level of resistance (sensitivity) to zoom in (0 - 10) - higher is less sensitive	3
pinchToZoomOutSensitivity	number	the level of resistance (sensitivity) to zoom out (0 - 10) - higher is less sensitive	1
movementSensibility	number	how resistant should shifting the view around be? (0.5 - 5) - higher is less sensitive	1.9
initialOffsetX	number	The horizontal offset the image should start at	0
initialOffsetY	number	The vertical offset the image should start at	0
contentHeight	number	Specify if you want to treat the height of the centered content inside the zoom subject as the zoom subject's height	undefined
contentWidth	number	Specify if you want to treat the width of the centered content inside the zoom subject as the zoom subject's width	undefined
panBoundaryPadding	number	At certain scales, the edge of the content is bounded too close to the edge of the container, making it difficult to pan to and interact with the edge of the content. To fix this, we'd wanna allow the content to pan just a little further away from the container's edge. Hence, the "pan boundary padding", measured in pixels.	0
longPressDuration	number	Duration in ms until a press is considered a long press	700
visualTouchFeedbackEnabled	boolean	Whether to show a touch feedback circle on touch	true

Callbacks

These events can be used to work with data after specific events.

name	description	params	expected return
onTransform	Will be called when the transformation configuration (zoom level and offset) changes	zoomableViewEventObject	void
onDoubleTapBefore	Will be called, at the start of a double tap	event, gestureState, zoomableViewEventObject	void
onDoubleTapAfter	Will be called at the end of a double tap	event, gestureState, zoomableViewEventObject	void
onShiftingBefore	Will be called, when user taps and moves the view, but before our view movement work kicks in (so this is the place to interrupt movement, if you need to)	event, gestureState, zoomableViewEventObject	{boolean} if this returns true, ZoomableView will not process the shift, otherwise it will
onShiftingAfter	Will be called, when user taps and moves the view, but after the values have changed already	event, gestureState, zoomableViewEventObject	void
onShiftingEnd	Will be called, when user stops a tap and move gesture	event, gestureState, zoomableViewEventObject	void
onZoomBefore	Will be called, while the user pinches the screen, but before our zoom work kicks in (so this is the place to interrupt zooming, if you need to)	event, gestureState, zoomableViewEventObject	{boolean} if this returns true, ZoomableView will not process the pinch, otherwise it will
onZoomAfter	Will be called, while the user pinches the screen, but after the values have changed already	event, gestureState, zoomableViewEventObject	{boolean} if this returns true, ZoomableView will not process the pinch, otherwise it will
onZoomEnd	Will be called after pinchzooming has ended	event, gestureState, zoomableViewEventObject	{boolean} if this returns true, ZoomableView will not process the pinch, otherwise it will
onLongPress	Will be called after the user pressed on the image for a while	event, gestureState	void

Methods

The following methods allow you to control the ZoomableView zoom level & position from your component. (think of control buttons, ...)

name	description	params	expected return
zoomTo	Changes the zoom level to a specific number	newZoomLevel: number, bindToBorders = true	Promise
zoomBy	Changes the zoom level relative to the current level (use positive numbers to zoom in, negative numbers to zoom out)	zoomLevelChange: number, bindToBorders = true	Promise
moveTo	Shifts the zoomed part to a specific point (in px relative to x: 0, y: 0)	newOffsetX: number, newOffsetY: number, bindToBorders = true	Promise
moveBy	Shifts the zoomed part by a specific pixel number	newOffsetX: number, newOffsetY: number, bindToBorders = true	Promise

Example:

export default function App() {
  // you will need a reference to the ReactNativeZoomableView component
  const zoomableViewRef = createRef<ReactNativeZoomableView>();

  return (
    <View style={styles.container}>
      <View style={styles.zoomWrapper}>
        <ReactNativeZoomableView
          ref={zoomableViewRef}
          bindToBorders={true}
        >
          <Text style={styles.caption}>HelloWorld</Text>
        </ReactNativeZoomableView>
      </View>

      <View style={styles.controlWrapperLeft}>
        {/* Here you see some examples of moveBy */}
        <Button onPress={() => zoomableViewRef.current!.moveBy(-30, 0)} title="⬅️" />
        <Button onPress={() => zoomableViewRef.current!.moveBy(30, 0)} title="➡️" />
        <Button onPress={() => zoomableViewRef.current!.moveBy(0, -30)} title="⬆️" />
        <Button onPress={() => zoomableViewRef.current!.moveBy(0, 30)} title="⬇️" />

        {/* Here you see an example of moveTo */}
        <Button onPress={() => zoomableViewRef.current!.moveTo(300, 200)} title="Move to" />
      </View>

      <View style={styles.controlWrapperRight}>
        {/* Here you see examples of zoomBy */}
        <Button onPress={() => zoomableViewRef.current!.zoomBy(-0.1)} title="-" />
        <Button onPress={() => zoomableViewRef.current!.zoomBy(0.1)} title="+" />

        {/* Here you see an example of zoomTo */}
        <Button onPress={() => zoomableViewRef.current!.zoomTo(1)} title="reset" />
      </View>
    </View>
  );
}

Pan Responder Hooks

Sometimes you need to change deeper level behavior, so we prepared these panresponder hooks for you.

name	description	params	expected return
onStartShouldSetPanResponder	description	event, gestureState, zoomableViewEventObject, baseComponentResult	{boolean} whether panresponder should be set or not
onPanResponderGrant	description	event, gestureState, zoomableViewEventObject	void
onPanResponderEnd	Will be called when gesture ends (more accurately, on pan responder "release")	event, gestureState, zoomableViewEventObject	void
onPanResponderTerminate	Will be called when the gesture is force-interrupted by another handler	event, gestureState, zoomableViewEventObject	void
onPanResponderTerminationRequest	Callback asking whether the gesture should be interrupted by another handler (iOS only due to facebook/react-native#27778, facebook/react-native#5696, ...)	event, gestureState, zoomableViewEventObject	void
onPanResponderMove	Will be called when user moves while touching	event, gestureState, zoomableViewEventObject	void
onShouldBlockNativeResponder	Returns whether this component should block native components from becoming the JS responder	event, gestureState, zoomableViewEventObject	boolean

zoomableViewEventObject

The zoomableViewEventObject object is attached to every event and represents the current state of our zoomable view.

   {
      zoomLevel: number,         // current level of zooming denoting the scale applied to the zoom subject (usually a value between minZoom and maxZoom)
      offsetX: number,           // current offset left
      offsetY: number,           // current offset top
      originalHeight: number,    // original height of the zoom subject
      originalWidth: number,     // original width of the zoom subject
      originalPageX: number,     // original absolute X of the zoom subject
      originalPageY: number,     // original absolite Y of the zoom subject
   }

Special configurations

Contributing

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

OpenSpace Labs

This library was authored by @SimonErich and is now maintained by OpenSpace Labs. Based in San Francisco, Openspace is "like Google StreetView plus Git for construction sites". We're doing a lot of cool things with AI, Machine Vision, 3D/2D Imagery, React/React Native, and more.

Join us and help revolutionize the construction industry. We're hiring on all fronts!

Check out our Glassdoor and blog posts.

License

MIT

License

memoryStack/react-native-zoomable-view

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