hidp-canvas-polyfill

hdpi-canvas-polyfill.js

function hdpiCanvasPolyfill (canvas) {
  var dpr = Math.max(1, window.devicePixelRatio || 1)
  var logicalWidth = canvas.width
  var logicalHeight = canvas.height

  canvas.width = dpr * logicalWidth
  canvas.height = dpr * logicalHeight
  canvas.style.width = `${logicalWidth}px`
  canvas.style.height = `${logicalHeight}px`

  var ctx = canvas.getContext('2d');
  ctx.scale(dpr, dpr);
}