Function drawSelectionRange

src/codemirror.js:2349–2421

(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;

    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; top: " + top + "px; width: " + (width == null ? rightSide - left : width) +
                               "px; 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);
      }

      iterateBidiSections(getOrder(lineObj), fromArg || 0, toArg == null ? lineLen : toArg, function(from, to, dir) {
        var leftPos = coords(from, "left"), rightPos, left, right;
        if (from == to) {
          rightPos = leftPos;
          left = right = leftPos.left;
        } else {
          rightPos = coords(to - 1, "right");
          if (dir == "rtl") { var tmp = leftPos; leftPos = rightPos; rightPos = tmp; }
          left = leftPos.left;
          right = rightPos.right;
        }
        if (fromArg == null && from == 0) left = leftSide;
        if (rightPos.top - leftPos.top > 3) { // Different lines, draw top part
          add(left, leftPos.top, null, leftPos.bottom);
          left = leftSide;
          if (leftPos.bottom < rightPos.top) add(left, leftPos.bottom, null, rightPos.top);
        }
        if (toArg == null && to == lineLen) right = rightSide;
        if (!start || leftPos.top < start.top || leftPos.top == start.top && leftPos.left < start.left)
          start = leftPos;
        if (!end || rightPos.bottom > end.bottom || rightPos.bottom == end.bottom && rightPos.right > end.right)
          end = rightPos;
        if (left < leftSide + 1) left = leftSide;
        add(left, rightPos.top, right - left, rightPos.bottom);
      });
      return {start: start, end: end};
    }

    var sFrom = range.from(), sTo = range.to();
    if (sFrom.line == sTo.line) {
      drawForLine(sFrom.line, sFrom.ch, sTo.ch);
    } else {
      var fromLine = getLine(doc, sFrom.line), toLine = getLine(doc, sTo.line);
      var singleVLine = visualLine(fromLine) == visualLine(toLine);
      var leftEnd = drawForLine(sFrom.line, sFrom.ch, singleVLine ? fromLine.text.length + 1 : null).end;