README.md

react-scrollable-canvas

react-scrollable-canvas is a React component library that you can create scrollable canvas easily and quickly.

Installation

Install react-scrollable-canvas with npm:

npm install react-scrollable-canvas --save

Example

import React, { Component, createRef } from 'react';
import { ScrollableCanvas } from 'react-scrollable-canvas';

const WIDTH = 300;
const HEIGHT = 300;
const LARGE_WIDTH = 600;
const LARGE_HEIGHT = 600;
const CIRCLE_RADIUS = 5;
const CIRCLE_SIZE = 30;

export default class ScrollableCanvasExample extends Component {
  canvasRef = createRef();
  ctx = null;

  draw = (scrollTop, scrollLeft) => {
    // draw canvas here.
    this.ctx.clearRect(0, 0, WIDTH, HEIGHT);
    for (let y = -scrollTop % CIRCLE_SIZE; y < HEIGHT - (scrollTop % CIRCLE_SIZE); y += CIRCLE_SIZE) {
      for (let x = -scrollLeft % CIRCLE_SIZE; x < WIDTH - (scrollLeft % CIRCLE_SIZE); x += CIRCLE_SIZE) {
        this.ctx.beginPath();
        this.ctx.arc(x + CIRCLE_SIZE / 2, y + CIRCLE_SIZE / 2, CIRCLE_RADIUS, 0, 360, false);
        this.ctx.fillStyle = `rgba(${(scrollLeft + x) / 2}, ${(scrollTop + y) / 2}, 128, 0.8)`;
        this.ctx.fill();
      }
    }
  };

  componentDidMount() {
    this.ctx = this.canvasRef.current.getContext('2d');
    this.draw(0, 0);
  }

  render() {
    return (
      <ScrollableCanvas
        width={WIDTH}
        height={HEIGHT}
        largeWidth={LARGE_WIDTH}
        largeHeight={LARGE_HEIGHT}
        canvasRef={this.canvasRef}
        onScroll={this.draw}
      />
    );
  }
}

Props

ScrollableCanvas Props

Name	Type	Description
width	number	Required. Width of the display size.
height	number	Required. Height of the display size.
largeWidth	number	Required. Width of the canvas size.
largeHeight	number	Required. Height of the canvas size.
wait	number	Function onScroll is called every (wait) milliseconds. Used for throttle function. Default value is 10.
noScrollbar	boolean	Hide scroll bar. Default value is false.
onScroll	(scrollTop: number, scrollLeft: number) => void	This function is called when scrolled.
canvasRef	React.RefObject	This references a canvas element inside ScrollableCanvas.

ScrollableCanvasContainer Props

Name	Type	Description
width	number	Required. Width of the display size.
height	number	Required. Height of the display size.
largeWidth	number	Required. Width of the canvas size.
largeHeight	number	Required. Height of the canvas size.
wait	number	Function onScroll is called every (wait) milliseconds. Used for throttle function. Default value is 10.
noScrollbar	boolean	Hide scroll bar. Default value is false.
onScroll	(scrollTop: number, scrollLeft: number) => void	This function is called when scrolled.
children	React.ReactNode	Children of ScrollableCanvasContainer.

Canvas Props

Name	Type	Description
width	number	Width css property. Default value is 500.
height	number	Height css property. Default value is 500.
translateX	number	translateX css property. Default value is 0.
translateY	number	translateY css property. Default value is 0.
top	number	top css property. Default value is 0.
left	number	left css property. Default value is 0.