Function calculateScrollPos

samples/common/codehighlight/codemirror.js:3471–3498

(cm, rect)

  // scrollLeft properties. When these are undefined, the
  // vertical/horizontal position does not need to be adjusted.
  function calculateScrollPos(cm, rect) {
    var display = cm.display, snapMargin = textHeight(cm.display);
    if (rect.top < 0) { rect.top = 0; }
    var screentop = cm.curOp && cm.curOp.scrollTop != null ? cm.curOp.scrollTop : display.scroller.scrollTop;
    var screen = displayHeight(cm), result = {};
    if (rect.bottom - rect.top > screen) { rect.bottom = rect.top + screen; }
    var docBottom = cm.doc.height + paddingVert(display);
    var atTop = rect.top < snapMargin, atBottom = rect.bottom > docBottom - snapMargin;
    if (rect.top < screentop) {
      result.scrollTop = atTop ? 0 : rect.top;
    } else if (rect.bottom > screentop + screen) {
      var newTop = Math.min(rect.top, (atBottom ? docBottom : rect.bottom) - screen);
      if (newTop != screentop) { result.scrollTop = newTop; }
    }

    var gutterSpace = cm.options.fixedGutter ? 0 : display.gutters.offsetWidth;
    var screenleft = cm.curOp && cm.curOp.scrollLeft != null ? cm.curOp.scrollLeft : display.scroller.scrollLeft - gutterSpace;
    var screenw = displayWidth(cm) - display.gutters.offsetWidth;
    var tooWide = rect.right - rect.left > screenw;
    if (tooWide) { rect.right = rect.left + screenw; }
    if (rect.left < 10)
      { result.scrollLeft = 0; }
    else if (rect.left < screenleft)
      { result.scrollLeft = Math.max(0, rect.left + gutterSpace - (tooWide ? 0 : 10)); }
    else if (rect.right > screenw + screenleft - 3)
      { result.scrollLeft = rect.right + (tooWide ? 0 : 10) - screenw; }
    return result
  }

  // Store a relative adjustment to the scroll position in the current
  // operation (to be applied when the operation finishes).