react-native-signature-canvas
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A performant, customizable React Native signature canvas with advanced error handling, WebView optimization, and TypeScript support for iOS, Android, and Expo
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# React Native Signature Canvas
[](https://www.npmjs.com/package/react-native-signature-canvas)
[](https://www.npmjs.com/package/react-native-signature-canvas)
[](https://github.com/expo/expo)
A React Native component for capturing signatures or drawing on a canvas with a smooth, native feel. Works on iOS, Android, and Expo.
## Features
- ✅ **Cross-platform support** (iOS, Android, Expo)
- ✅ **Smooth, responsive drawing experience** with optimized performance
- ✅ **Customizable pen color, size, and background**
- ✅ **Support for background and overlay images**
- ✅ **Export signatures** as PNG, JPEG, or SVG
- ✅ **Undo/redo functionality**
- ✅ **Drawing and erasing modes**
- ✅ **Full TypeScript support** with enhanced type definitions
- 🆕 **Advanced error handling** with automatic recovery
- 🆕 **Performance monitoring** and optimization
- 🆕 **Flexible WebView customization** via `webviewProps`
- 🆕 **Enhanced security** with configurable restrictions
- 🆕 **Memory management** and leak prevention
## Installation
### For React Native ≥ 0.60.0 or Expo SDK ≥ 35.0.0
```bash
yarn add react-native-signature-canvas
```
or
```bash
npm install --save react-native-signature-canvas
```
> This package depends on [react-native-webview](https://github.com/react-native-webview/react-native-webview). If you're using React Native CLI (not Expo), you'll need to install react-native-webview separately:
>
> ```bash
> yarn add react-native-webview
> cd ios && pod install
> ```
### For React Native < 0.60.0 or Expo SDK < 33.0.0
```bash
npm install --save react-native-signature-canvas@1.4.2
```
## Basic Usage
```jsx
import React, { useRef, useState } from 'react';
import { StyleSheet, View, Image } from 'react-native';
import SignatureCanvas from 'react-native-signature-canvas';
const SignatureScreen = () => {
const [signature, setSignature] = useState(null);
const [isLoading, setIsLoading] = useState(false);
const ref = useRef();
const handleSignature = (signature) => {
console.log('Signature captured:', signature);
setSignature(signature);
setIsLoading(false);
};
const handleEmpty = () => {
console.log('Signature is empty');
setIsLoading(false);
};
const handleClear = () => {
console.log('Signature cleared');
setSignature(null);
};
const handleError = (error) => {
console.error('Signature pad error:', error);
setIsLoading(false);
};
const handleEnd = () => {
setIsLoading(true);
ref.current?.readSignature();
};
return (
<View style={styles.container}>
<View style={styles.preview}>
{signature && (
<Image
resizeMode="contain"
style={{ width: 335, height: 114 }}
source={{ uri: signature }}
/>
)}
</View>
<SignatureCanvas
ref={ref}
onEnd={handleEnd}
onOK={handleSignature}
onEmpty={handleEmpty}
onClear={handleClear}
onError={handleError}
autoClear={true}
descriptionText="Sign here"
clearText="Clear"
confirmText={isLoading ? "Processing..." : "Save"}
penColor="#000000"
backgroundColor="rgba(255,255,255,0)"
webviewProps={{
// Custom WebView optimization
cacheEnabled: true,
androidLayerType: "hardware",
}}
/>
</View>
);
};
const styles = StyleSheet.create({
container: {
flex: 1,
},
preview: {
width: 335,
height: 114,
backgroundColor: '#F8F8F8',
justifyContent: 'center',
alignItems: 'center',
marginTop: 15,
},
});
export default SignatureScreen;
```
## Props
| Prop | Type | Default | Description |
|------|------|---------|-------------|
| `androidHardwareAccelerationDisabled` | `boolean` | `false` | Disable hardware acceleration on Android |
| `autoClear` | `boolean` | `false` | Auto clear signature after clicking the Confirm button |
| `backgroundColor` | `string` | `rgba(255,255,255,0)` | Background color of the canvas |
| `bgHeight` | `number` | `0` | Height of the background image |
| `bgWidth` | `number` | `0` | Width of the background image |
| `bgSrc` | `string` | `null` | Background image source URI |
| `clearText` | `string` | `Clear` | Clear button text |
| `confirmText` | `string` | `Confirm` | Save button text |
| `customHtml` | `(injectedJavaScript: string) => string` | `null` | Custom HTML template for the canvas |
| `dataURL` | `string` | `""` | Base64 string to draw saved signature |
| `descriptionText` | `string` | `Sign above` | Description text for signature |
| `dotSize` | `number` | `null` | Radius of a single dot |
| `imageType` | `string` | `image/png` | Image type for export (`image/png`, `image/jpeg`, `image/svg+xml`) |
| `minWidth` | `number` | `0.5` | Minimum width of a line |
| `maxWidth` | `number` | `2.5` | Maximum width of a line |
| `nestedScrollEnabled` | `boolean` | `false` | Enable nested scrolling for use inside a ScrollView |
| `showsVerticalScrollIndicator` | `boolean` | `true` | Show vertical scroll indicator in WebView |
| `onOK` | `function` | - | Callback after saving non-empty signature |
| `onEmpty` | `function` | - | Callback after trying to save an empty signature |
| `onClear` | `function` | - | Callback after clearing the signature |
| `onGetData` | `function` | - | Callback when getData() is called |
| `onBegin` | `function` | - | Callback when a new stroke is started |
| `onEnd` | `function` | - | Callback when the stroke has ended |
| `onLoadEnd` | `function` | - | Callback when the WebView canvas load ended |
| `onUndo` | `function` | - | Callback when undo() is called |
| `onRedo` | `function` | - | Callback when redo() is called |
| `onDraw` | `function` | - | Callback when drawing is enabled |
| `onErase` | `function` | - | Callback when erasing is enabled |
| `onChangePenColor` | `function` | - | Callback after changing the pen color |
| `onChangePenSize` | `function` | - | Callback after changing the pen size |
| `overlayHeight` | `number` | `0` | Height of the overlay image |
| `overlayWidth` | `number` | `0` | Width of the overlay image |
| `overlaySrc` | `string` | `null` | Overlay image source URI (must be PNG with transparent background) |
| `penColor` | `string` | `black` | Color of the pen |
| `rotated` | `boolean` | `false` | Rotate signature pad 90 degrees |
| `style` | `object` | - | Style of the wrapper view |
| `scrollable` | `boolean` | `false` | Enable scrolling in the signature pad |
| `trimWhitespace` | `boolean` | `false` | Trim image whitespace |
| `webStyle` | `string` | - | WebView style to override default style |
| `webviewContainerStyle` | `object` | - | Style for the WebView container |
| `androidLayerType` | `none\|software\|hardware` | `hardware` | Sets the Android WebView layer type |
| `onError` | `function` | - | Callback when an error occurs |
| `webviewProps` | `object` | `{}` | Additional props to pass to the underlying WebView |
## Methods
Access these methods using a ref to the SignatureCanvas component.
| Method | Description |
|--------|-------------|
| `clearSignature()` | Clear the current signature |
| `changePenColor(color)` | Change pen color |
| `changePenSize(minW, maxW)` | Change pen size |
| `draw()` | Enable drawing mode |
| `erase()` | Enable erasing mode |
| `getData()` | Triggers the `onGetData` callback with signature data |
| `readSignature()` | Read the current signature and trigger callbacks |
| `undo()` | Undo last stroke |
| `redo()` | Redo last stroke |
## WebView Customization (New!)
The `webviewProps` parameter allows you to customize the underlying WebView behavior while maintaining signature functionality:
```jsx
<SignatureCanvas
// ... other props
webviewProps={{
// Performance optimization
cacheEnabled: true,
androidLayerType: "hardware",
androidHardwareAccelerationDisabled: false,
// Security settings
allowFileAccess: false,
allowFileAccessFromFileURLs: false,
mixedContentMode: "never",
// UI customization
decelerationRate: 'fast',
bounces: false,
// Any other WebView props...
}}
/>
```
### Performance Optimization Examples
```jsx
// High-performance mode
<SignatureCanvas
webviewProps={{
cacheEnabled: true,
androidLayerType: "hardware",
androidHardwareAccelerationDisabled: false,
}}
/>
// Low-memory mode
<SignatureCanvas
webviewProps={{
cacheEnabled: false,
androidLayerType: "software",
androidHardwareAccelerationDisabled: true,
}}
/>
```
## Error Handling (Enhanced!)
```jsx
const [error, setError] = useState(null);
const handleError = (error) => {
console.error('Signature error:', error);
setError(error.message);
// Error recovery is automatic, but you can handle it here
};
<SignatureCanvas
onError={handleError}
// Component automatically retries on recoverable errors
/>
{error && (
<Text style={{ color: 'red' }}>Error: {error}</Text>
)}
```
## Advanced Usage
### Using a Background Image
```jsx
const imgWidth = 300;
const imgHeight = 200;
const style = `.m-signature-pad {box-shadow: none; border: none; }
.m-signature-pad--body {border: none;}
.m-signature-pad--footer {display: none; margin: 0px;}
body,html {
width: ${imgWidth}px; height: ${imgHeight}px;}`;
<View style={{ width: imgWidth, height: imgHeight }}>
<SignatureCanvas
ref={ref}
bgSrc="https://example.com/background.jpg"
bgWidth={imgWidth}
bgHeight={imgHeight}
webStyle={style}
onOK={handleSignature}
/>
</View>
```
### Using an Overlay Image
```jsx
const imgWidth = 256;
const imgHeight = 256;
const style = `.m-signature-pad {box-shadow: none; border: none; }
.m-signature-pad--body {border: none;}
.m-signature-pad--footer {display: none; margin: 0px;}
body,html {
width: ${imgWidth}px; height: ${imgHeight}px;}`;
<View style={{ width: imgWidth, height: imgHeight }}>
<SignatureCanvas
ref={ref}
overlaySrc="https://example.com/overlay.png" // Must be PNG with transparent background
overlayWidth={imgWidth}
overlayHeight={imgHeight}
webStyle={style}
onOK={handleSignature}
/>
</View>
```
### Using in a Modal
```jsx
import React, { useState, useRef } from 'react';
import { StyleSheet, View, TouchableOpacity, Modal, Text } from 'react-native';
import SignatureCanvas from 'react-native-signature-canvas';
const SignatureModal = ({ onSignature }) => {
const [show, setShow] = useState(false);
const ref = useRef();
const handleSignature = (signature) => {
onSignature(signature);
setShow(false);
};
return (
<View>
<TouchableOpacity onPress={() => setShow(true)}>
<Text>Open Signature Pad</Text>
</TouchableOpacity>
{show && (
<Modal>
<SignatureCanvas
ref={ref}
onOK={handleSignature}
onEmpty={() => console.log('Empty')}
descriptionText="Sign here"
penColor="rgba(255,117,2,1)"
/>
</Modal>
)}
</View>
);
};
```
### Scrollable Signature Canvas
```jsx
import React, { useRef, useState } from 'react';
import { View, StyleSheet, ScrollView } from 'react-native';
import SignatureCanvas from 'react-native-signature-canvas';
const ScrollableSignature = () => {
const [scrollEnabled, setScrollEnabled] = useState(true);
const signatureRef = useRef(null);
return (
<ScrollView scrollEnabled={scrollEnabled}>
<View style={styles.container}>
<SignatureCanvas
ref={signatureRef}
style={styles.canvas}
onBegin={() => setScrollEnabled(false)}
onEnd={() => setScrollEnabled(true)}
/>
</View>
</ScrollView>
);
};
const styles = StyleSheet.create({
container: {
flex: 1,
alignItems: 'center',
},
canvas: {
width: '90%',
height: 300,
borderWidth: 1,
borderColor: '#000',
},
});
```
## Performance & Reliability
### Performance Features
- **Debounced resize handling** for smooth interaction
- **Memory pressure detection** with adaptive optimization
- **Optimized rendering** with reduced re-renders
- **Device-specific optimization** based on hardware capabilities
### Security Enhancements
- **Configurable WebView security** via `webviewProps`
- **Input validation** for all methods and callbacks
- **XSS protection** with content security policies
- **File access restrictions** by default
## Migration Guide
### From v4.x to v5.x
This version is fully backward compatible. New features:
```jsx
// NEW: Enhanced error handling
<SignatureCanvas
onError={(error) => console.error(error)} // New callback
/>
// NEW: WebView customization
<SignatureCanvas
webviewProps={{ // New prop
cacheEnabled: false,
androidLayerType: "software"
}}
/>
```
## Troubleshooting
### Common Issues
**Issue**: Signature pad not loading
```jsx
// Solution: Add error handling and check WebView props
<SignatureCanvas
onError={(error) => console.log('Error:', error)}
onLoadEnd={() => console.log('Loaded successfully')}
webviewProps={{
startInLoadingState: true,
renderLoading: () => <ActivityIndicator />
}}
/>
```
**Issue**: Poor performance on older devices
```jsx
// Solution: Use low-performance mode
<SignatureCanvas
webviewProps={{
androidLayerType: "software",
androidHardwareAccelerationDisabled: true,
cacheEnabled: false
}}
/>
```
**Issue**: Memory issues
```jsx
// Solution: The component now handles this automatically
// But you can customize via webviewProps if needed
<SignatureCanvas
webviewProps={{
cacheEnabled: false, // Reduce memory usage
androidLayerType: "software" // Use software rendering
}}
/>
```
## API Reference
For detailed API documentation, see:
- [WEBVIEW_PROPS.md](./WEBVIEW_PROPS.md) - WebView customization guide
- [TypeScript definitions](./index.d.ts) - Complete type definitions
## Core Technology
This component is built on:
- [signature_pad.js](https://github.com/szimek/signature_pad) for the core signature functionality
- React Native WebView for cross-platform rendering
- Enhanced with performance monitoring and error recovery systems
## Contributing
Contributions are welcome! Please read our contributing guidelines and submit pull requests to help improve this component.
### Development Setup
```bash
# Clone the repository
git clone https://github.com/YanYuanFE/react-native-signature-canvas.git
# Install dependencies
cd react-native-signature-canvas
npm install
# Run example apps
cd example/expo-app
npm install && npm start
```
## Changelog
### v5.0.1 (Latest)
- 🆕 Added `webviewProps` for WebView customization
- 🆕 Enhanced error handling with automatic recovery
- 🆕 Performance monitoring and optimization
- 🆕 Memory leak prevention
- 🆕 Improved TypeScript definitions
- 🔧 Fixed global variable pollution in WebView JavaScript
- 🔧 Added input validation for all methods
- ⚡ Optimized rendering performance
[View full changelog](./CHANGELOG.md)
## License
MIT License - see [LICENSE](./LICENSE) file for details.
## Buy Me a Coffee ☕
If you find this project helpful, consider supporting its development with cryptocurrency donations:
### Cryptocurrency Donations
| Currency | Address | QR Code |
|----------|---------|----------|
| **Bitcoin (BTC)** | `bc1phyz9agr0m9l2w9pd8w85w4da2jt3wl4cre7vv0qq4uesm3fv00pscu96tux` |  |
| **Ethereum (ETH)** | `0xf5dfe16b1e64e8e3a92063fb2922447e13b48945` |  |
| **Solana (SOL)** | `3VuhyeTj3hMSrmzq7NctHkgFxvJrmtAUQTzagEBEu3Vm` |  |
### Other Ways to Support
- ⭐ Star this repository
- 🐛 Report bugs and issues
- 💡 Suggest new features
- 🤝 Contribute code improvements
- 📢 Share this project with others
Your support helps maintain and improve this open-source project. Thank you! 🙏
---
**Made with ❤️ for the React Native community**