@benjeau/react-native-draw

Cross-platform React Native drawing component based on SVG

Installation

npm install @benjeau/react-native-draw
# or
yarn add @benjeau/react-native-draw

Also, you need to install react-native-gesture-handler and react-native-svg, and follow their installation instructions.

Extras

Supporting components, such as CanvasControls, ColorPicker and BrushProperties components, are available as a separate package, @benjeau/react-native-draw-extras

Usage

All the following examples are also available in the example Expo application

Simple example

Here's the most simple example:

import React from 'react';
import { Canvas } from '@benjeau/react-native-draw';

export default () => <Canvas />;

Demo.-.Simple.Example.mp4

Complex example

Here's a more complex example:

Complex example - Code snippet

import React, { useRef } from 'react';
import { Button } from 'react-native';
import { Canvas, CanvasRef } from '@benjeau/react-native-draw';

export default () => {
  const canvasRef = useRef<CanvasRef>(null);

  const handleUndo = () => {
    canvasRef.current?.undo();
  };

  const handleClear = () => {
    canvasRef.current?.clear();
  };

  return (
    <>
      <Canvas
        ref={canvasRef}
        height={600}
        color="red"
        thickness={20}
        opacity={0.6}
        style={{ backgroundColor: 'black' }}
      />
      <Button title="Undo" onPress={handleUndo} />
      <Button title="Clear" onPress={handleClear} />
    </>
  );
};

Demo.-.Complex.Example.mp4

Example with @BenJeau/react-native-draw-extras

This uses the @benjeau/react-native-draw-extras npm package for the color picker and the bottom buttons/brush preview.

As this package does not depend on @BenJeau/react-native-draw-extras, it is completely optional and you can build your own supporting UI, just like the previous example

Extras example - Code snippet

import React, { useRef, useState } from 'react';
import { Animated, StyleSheet, View } from 'react-native';
import {
  BrushProperties,
  Canvas,
  CanvasControls,
  CanvasRef,
  DEFAULT_COLORS,
  DrawingTool,
} from '@benjeau/react-native-draw';

export default () => {
  const canvasRef = useRef<CanvasRef>(null);

  const [color, setColor] = useState(DEFAULT_COLORS[0][0][0]);
  const [thickness, setThickness] = useState(5);
  const [opacity, setOpacity] = useState(1);
  const [tool, setTool] = useState(DrawingTool.Brush);
  const [visibleBrushProperties, setVisibleBrushProperties] = useState(false);

  const handleUndo = () => {
    canvasRef.current?.undo();
  };

  const handleClear = () => {
    canvasRef.current?.clear();
  };

  const handleToggleEraser = () => {
    setTool((prev) =>
      prev === DrawingTool.Brush ? DrawingTool.Eraser : DrawingTool.Brush
    );
  };

  const [overlayOpacity] = useState(new Animated.Value(0));
  const handleToggleBrushProperties = () => {
    if (!visibleBrushProperties) {
      setVisibleBrushProperties(true);

      Animated.timing(overlayOpacity, {
        toValue: 1,
        duration: 200,
        useNativeDriver: true,
      }).start();
    } else {
      Animated.timing(overlayOpacity, {
        toValue: 0,
        duration: 200,
        useNativeDriver: true,
      }).start(() => {
        setVisibleBrushProperties(false);
      });
    }
  };

  return (
    <>
      <Canvas
        ref={canvasRef}
        height={600}
        color={color}
        thickness={thickness}
        opacity={opacity}
        tool={tool}
        style={{
          borderBottomWidth: StyleSheet.hairlineWidth,
          borderColor: '#ccc',
        }}
      />
      <View>
        <CanvasControls
          onUndo={handleUndo}
          onClear={handleClear}
          onToggleEraser={handleToggleEraser}
          onToggleBrushProperties={handleToggleBrushProperties}
          tool={tool}
          color={color}
          opacity={opacity}
          thickness={thickness}
        />
        {visibleBrushProperties && (
          <BrushProperties
            color={color}
            thickness={thickness}
            opacity={opacity}
            onColorChange={setColor}
            onThicknessChange={setThickness}
            onOpacityChange={setOpacity}
            style={{
              position: 'absolute',
              bottom: 80,
              left: 0,
              right: 0,
              padding: 10,
              backgroundColor: '#f2f2f2',
              borderTopEndRadius: 10,
              borderTopStartRadius: 10,
              borderWidth: StyleSheet.hairlineWidth,
              borderBottomWidth: 0,
              borderTopColor: '#ccc',
              opacity: overlayOpacity,
            }}
          />
        )}
      </View>
    </>
  );
};

Demo.-.Extras.Example.mp4

Props

Canvas

name	description	type	default
color	Color of the brush strokes	string	- (required)
thickness	Thickness of the brush strokes	number	- (required)
opacity	Opacity of the brush strokes	number	- (required)
initialPaths	Paths to be already drawn	PathType[]	[]
height	Height of the canvas	number	height of the window - 80
width	Width of the canvas	number	width of the window
style	Override the style of the container of the canvas	StyleProp	-
onPathsChange	Callback function when paths change	(paths: PathType[]) => any	-
simplifyOptions	SVG simplification options	SimplifyOptions	see below
eraserSize	Width of eraser (to compensate for path simplification)	number	5
tool	Initial tool of the canvas	brush or eraser	brush
combineWithLatestPath	Combine current path with the last path if it's the same color, thickness, and opacity	boolean	false
enabled	Allows for the canvas to be drawn on, put to false if you want to disable/lock the canvas	boolean	true

SimplifyOptions

name	description	type	default
simplifyPaths	Enable SVG path simplification on paths, except the one currently being drawn	boolean	true
simplifyCurrentPath	Enable SVG path simplification on the stroke being drawn	boolean	false
amount	Amount of simplification to apply	number	10
roundPoints	Ignore fractional part in the points. Improves performance	boolean	true

Ref functions

name	description	type
undo	Undo last brush stroke	() => void
clear	Removes all brush strokes	() => void
getPaths	Get brush strokes data	() => PathType[]
addPath	Append a path to the current drawing paths	(path: PathType) => void
getSvg	Get SVG path string of the drawing	() => string

Troubleshooting

If you cannot draw on the canvas, make sure you have followed the extra steps of react-native-gesture-handler

Helper functions

• If you need to create an SVG path, createSVGPath() is available to create the string representation of an SVG path.

Contributing

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

License

MIT