Function drawSelectionRange

samples/common/codehighlight/codemirror.js:3180–3270

(cm, range, output)

  // Draws the given range as a highlighted selection
  function drawSelectionRange(cm, range, output) {
    var display = cm.display, doc = cm.doc;
    var fragment = document.createDocumentFragment();
    var padding = paddingH(cm.display), leftSide = padding.left;
    var rightSide = Math.max(display.sizerWidth, displayWidth(cm) - display.sizer.offsetLeft) - padding.right;
    var docLTR = doc.direction == "ltr";

    function add(left, top, width, bottom) {
      if (top < 0) { top = 0; }
      top = Math.round(top);
      bottom = Math.round(bottom);
      fragment.appendChild(elt("div", null, "CodeMirror-selected", ("position: absolute; left: " + left + "px;\n                             top: " + top + "px; width: " + (width == null ? rightSide - left : width) + "px;\n                             height: " + (bottom - top) + "px")));
    }

    function drawForLine(line, fromArg, toArg) {
      var lineObj = getLine(doc, line);
      var lineLen = lineObj.text.length;
      var start, end;
      function coords(ch, bias) {
        return charCoords(cm, Pos(line, ch), "div", lineObj, bias)
      }

      function wrapX(pos, dir, side) {
        var extent = wrappedLineExtentChar(cm, lineObj, null, pos);
        var prop = (dir == "ltr") == (side == "after") ? "left" : "right";
        var ch = side == "after" ? extent.begin : extent.end - (/\s/.test(lineObj.text.charAt(extent.end - 1)) ? 2 : 1);
        return coords(ch, prop)[prop]
      }

      var order = getOrder(lineObj, doc.direction);
      iterateBidiSections(order, fromArg || 0, toArg == null ? lineLen : toArg, function (from, to, dir, i) {
        var ltr = dir == "ltr";
        var fromPos = coords(from, ltr ? "left" : "right");
        var toPos = coords(to - 1, ltr ? "right" : "left");

        var openStart = fromArg == null && from == 0, openEnd = toArg == null && to == lineLen;
        var first = i == 0, last = !order || i == order.length - 1;
        if (toPos.top - fromPos.top <= 3) { // Single line
          var openLeft = (docLTR ? openStart : openEnd) && first;
          var openRight = (docLTR ? openEnd : openStart) && last;
          var left = openLeft ? leftSide : (ltr ? fromPos : toPos).left;
          var right = openRight ? rightSide : (ltr ? toPos : fromPos).right;
          add(left, fromPos.top, right - left, fromPos.bottom);
        } else { // Multiple lines
          var topLeft, topRight, botLeft, botRight;
          if (ltr) {
            topLeft = docLTR && openStart && first ? leftSide : fromPos.left;
            topRight = docLTR ? rightSide : wrapX(from, dir, "before");
            botLeft = docLTR ? leftSide : wrapX(to, dir, "after");
            botRight = docLTR && openEnd && last ? rightSide : toPos.right;
          } else {
            topLeft = !docLTR ? leftSide : wrapX(from, dir, "before");
            topRight = !docLTR && openStart && first ? rightSide : fromPos.right;
            botLeft = !docLTR && openEnd && last ? leftSide : toPos.left;
            botRight = !docLTR ? rightSide : wrapX(to, dir, "after");
          }
          add(topLeft, fromPos.top, topRight - topLeft, fromPos.bottom);
          if (fromPos.bottom < toPos.top) { add(leftSide, fromPos.bottom, null, toPos.top); }