magnifier

一个普通的放大镜

如上所述

测试用例

引入方式

script

<script src="https://magnifier.oulaoula.cn/dist/magnifier.js"></script>

module npm

    npm install magnifier --save

使用方式

    // 新版扩散
    drawMagnifier(magCtx, bgCtx, bounds);
    // 系统缩放
    drawSystemMagnifier(magCtx, canvasSize, canvasImg, bounds);

drawMagnifier

• magCtx CanvasRenderingContext2D - 放大镜所在画布
• bgCtx CanvasRenderingContext2D - 背景所在画布
• bounds IBounds - 放大区域

drawSystemMagnifier

• magCtx CanvasRenderingContext2D - 放大镜所在画布
• size ISize - 背景尺寸
• image Image - 背景图
• bounds IBounds - 放大区域

IBounds - 区域

• width number
• height number
• x number
• y number

例子

// node
// import { drawImageByUrl, drawSystemMagnifier } from 'magnifier';

const canvas = document.querySelector("canvas");
const ctx = canvas.getContext("2d");
const bgUrl = "https://magnifier.oulaoula.cn/bg.jpeg";

const magnifier = document.createElement("canvas");
magnifier.style.position = "fixed";
magnifier.style.right = "0";
magnifier.style.bottom = "0";
magnifier.width = 190;
magnifier.height = 190;
const magCtx = magnifier.getContext("2d");

document.body.appendChild(magnifier);

let img;

drawImageByUrl(ctx, canvas, bgUrl, (res) => {
  img = res;
});

canvas.onmousemove = function (e) {
  const { offsetX, offsetY } = e;
  window.requestAnimationFrame(function () {
    const bounds = {
      x: offsetX - 9,
      y: offsetY - 9,
      width: 19,
      height: 19,
    };
    // 新版扩散
    drawSystemMagnifier(magCtx, canvas, img, bounds);
  });
};