Function findViewIndex

static/editor.md/lib/codemirror/lib/codemirror.js:3219–3228

(cm, n)

  // Find the view element corresponding to a given line. Return null
  // when the line isn't visible.
  function findViewIndex(cm, n) {
    if (n >= cm.display.viewTo) return null;
    n -= cm.display.viewFrom;
    if (n < 0) return null;
    var view = cm.display.view;
    for (var i = 0; i < view.length; i++) {
      n -= view[i].size;
      if (n < 0) return i;
    }
  }

  function viewCuttingPoint(cm, oldN, newN, dir) {
    var index = findViewIndex(cm, oldN), diff, view = cm.display.view;