Function handleWheel

internal/driver/html/common.js:71–76

(e)

  }

  function handleWheel(e) {
    if (e.deltaY == 0) return;
    // Change scale factor by 1.1 or 1/1.1
    rescale(currentScale * (e.deltaY < 0 ? 1.1 : (1/1.1)),
            toSvg(e.offsetX, e.offsetY));
  }

  function setMode(m) {
    mode = m;