Create a high-DPI-compatible canvas element

high-dpi-canvas.js

function createHighDPICanvas(width, height){
  let dpi = window.devicePixelRatio || 1
  let canvas = document.createElement("canvas")
  canvas.width = width * dpi
  canvas.height = height * dpi
  canvas.style.width = width + "px"
  canvas.style.height = height + "px"
  canvas.getContext("2d").scale(dpi, dpi)
  return canvas
}