Function adjustView

src/codemirror.js:3386–3403

(cm, from, to)

  // Force the view to cover a given range, adding empty view element
  // or clipping off existing ones as needed.
  function adjustView(cm, from, to) {
    var display = cm.display, view = display.view;
    if (view.length == 0 || from >= display.viewTo || to <= display.viewFrom) {
      display.view = buildViewArray(cm, from, to);
      display.viewFrom = from;
    } else {
      if (display.viewFrom > from)
        display.view = buildViewArray(cm, from, display.viewFrom).concat(display.view);
      else if (display.viewFrom < from)
        display.view = display.view.slice(findViewIndex(cm, from));
      display.viewFrom = from;
      if (display.viewTo < to)
        display.view = display.view.concat(buildViewArray(cm, display.viewTo, to));
      else if (display.viewTo > to)
        display.view = display.view.slice(0, findViewIndex(cm, to));
    }
    display.viewTo = to;
  }

  // Count the number of lines in the view whose DOM representation is
  // out of date (or nonexistent).