@bizcharts/rax-canvas

@bizcharts/rax-canvas

Rax跨端canvas组件，支持宽高自适应、H5与小程序绘图上下文获取，API与W3C标准一致。

目前支持运行时和编译时的阿里小程序，以及运行时的微信小程序。

Install

$ npm install @bizcharts/rax-canvas --save

Usage

import RaxExample from '@bizcharts/rax-canvas';

API

Props

name	type	default	describe
prefix	string;	bx-rax	画布ID前缀
autoFit	boolean;	true	自适应宽高
width	number;	/	画布宽度
height	number;	/	画布高度
pixelRatio	number;	2	清晰度
hasBackCanvas	boolean;	false	是否需要离屏canvas
style	ICanvasInfo;	/	CSS样式
events	{ onTouchStart: any; onTouchMove: any; onTouchEnd: any; onTouchCancel: any; onLongPress: any; }	/	事件(不推荐使用)
onTouchStart	e=>void	/	触摸开始事件
onTouchMove	e=>void	/	触摸移动事件
onTouchEnd	e=>void	/	触摸结束事件
onTouchCancel	e=>void	/	触摸取消事件
onLongPress	e=>void	/	长触事件

ICanvasInfo

name	type	default	describe
context	CanvasRenderingContext2D;	/	绘图上下文
backContext	CanvasRenderingContext2D;	/	离屏绘图上下文
width	number;	/	画布宽度
height	number;	/	画布高度
pixelRatio	number;	2	清晰度

Function

name	param	return	describe
onGetCanvasInfo	info=>void	/	describe

Example

import { createElement, render } from 'rax';
import DriverUniversal from 'driver-universal';
import Canvas from '@bizcharts/rax-canvas';

function App() {
  let req;
  const handleDraw = (info) => {
    const { context: ctx, width, height } = info;

    var ball = {
      x: 100,
      y: 100,
      vx: 5,
      vy: 2,
      radius: 25,
      color: 'blue',
      draw: function () {
        ctx.beginPath();
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, true);
        ctx.closePath();
        ctx.fillStyle = this.color;
        ctx.fill();
        if (ctx.draw) {
          ctx.draw();
        }
      },
    };

    function draw() {
      ctx.clearRect(0, 0, width, height);
      ball.draw();
      ball.x += ball.vx;
      ball.y += ball.vy;

      if (ball.y + ball.vy > height - ball.radius || ball.y + ball.vy < ball.radius) {
        ball.vy = -ball.vy;
      }
      if (ball.x + ball.vx > width - ball.radius || ball.x + ball.vx < ball.radius) {
        ball.vx = -ball.vx;
      }
      req = requestAnimationFrame(draw);
    }

    req = requestAnimationFrame(draw);

    
  };
    useEffect(() => {
      return () => {
        cancelAnimationFrame(req);
      };
    }, []);
  return <Canvas style={{ border: '1px solid #e3e3e3', margin: 10 }} height={300} onGetCanvasInfo={handleDraw} />;
}

render(<App />, document.body, { driver: DriverUniversal });