最近在使用 canvas 画图的时候，遇到了图像文字模糊的问题，解决思路就是根据分辨率创建不同尺寸的画布。以下是创建高分辨率画布的代码：

/**

 * 创建高分辨率画布

 * @param w     画布宽

 * @param h     画布高

 * @param ratio 屏幕分辨率

 */

function createHiDPICanvas(w, h, ratio?) {

  const PIXEL_RATIO = (function () {

    const c = <HTMLCanvasElement>document.createElement("canvas"),

      ctx = c.getContext("2d"),

      dpr = window.devicePixelRatio || 1,

      bsr = ctx['webkitBackingStorePixelRatio'] ||

        ctx['mozBackingStorePixelRatio'] ||

        ctx['msBackingStorePixelRatio'] ||

        ctx['oBackingStorePixelRatio'] ||

        ctx['backingStorePixelRatio'] || 1;

    return dpr / bsr;

  })();

  if (!ratio) { ratio = PIXEL_RATIO; }

  const can = document.createElement("canvas");

  can.width = w * ratio;

  can.height = h * ratio;

  can.style.width = w + "px";

  can.style.height = h + "px";

  can.getContext("2d").setTransform(ratio, 0, 0, ratio, 0, 0);

  return can;

}

// 不创建高分辨率画布

const canvas = document.createElement("canvas");

canvas.width = 100;

canvas.height = 100;

// 创建使用默认分辨率的画布

const myCanvas = this.createHiDPICanvas(100, 100);

// 创建分辨率为 3 的画布

const myCustomCanvas = this.createHiDPICanvas(100, 100, 3);

最后，贴一个高分辨率画布的开源库

https://github.com/jondavidjohn/hidpi-canvas-polyfill