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@benjeau/react-native-draw

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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