meridian scaling script

scale.js

let width, height, pixelRatio;

const W = window;
const defaultAspect = 9 / 16;
const aspect = W.A || defaultAspect;
const targetHeight = W.S || 2048;
const targetWidth = ~~(targetHeight * aspect);
const inputHeight = W.H || W.innerHeight * W.devicePixelRatio;
const targetRatio =
  W.R != null ? W.R : Math.max(1, inputHeight / targetHeight);

height = targetHeight;
width = ~~(height * aspect);

pixelRatio = targetRatio;

let canvas;
if (W.C) canvas = W.C;
else if (D && D.body && D.createElement) {
  canvas = D.body.appendChild(D.createElement("canvas"));
}

const context = canvas ? canvas.getContext("2d") : null;
if (canvas) {
  canvas.width = ~~(width * pixelRatio);
  canvas.height = ~~(height * pixelRatio);
  const CS = canvas.style;
  if (CS) {
    const resize = () => {
      CS.position = "absolute";
      CS.display = "block";
      CS.top = CS.left = CS.right = CS.bottom = "0";
      CS.width = CS.margin = "auto";
      CS.height = "100%";
    };
    W.onresize = resize;
    resize();
  }
}