Method wheel

script.js:1003–1023

(e)

    let gestureStartScale = 0;

    let wheel = function(e) {
      if (e.ctrlKey || e.shiftKey) {
        e.preventDefault();
        let delta = e.deltaY;
        if (!Math.abs(delta) && e.deltaX != 0) {
          delta = e.deltaX * 0.5;
        }
        let scale = 1;
        scale -= delta * 0.01;
        // Your zoom/scale factor
        callback(scale, 0);
      } else if (e.altKey) {
        let delta = e.deltaY;
        if (!Math.abs(delta) && e.deltaX != 0) {
          delta = e.deltaX * 0.5;
        }
        let rot = -delta * 0.1;
        // Your zoom/scale factor
        callback(0, rot);
      }
    }
    // safari
    let gesturestart = function(e) {
      this.gesturing = true;