Function updateSelection

GUI/codemirror/lib/codemirror.js:1240–1268

(cm)

  // Redraw the selection and/or cursor
  function updateSelection(cm) {
    var display = cm.display, doc = cm.doc;
    var curFragment = document.createDocumentFragment();
    var selFragment = document.createDocumentFragment();

    for (var i = 0; i < doc.sel.ranges.length; i++) {
      var range = doc.sel.ranges[i];
      var collapsed = range.empty();
      if (collapsed || cm.options.showCursorWhenSelecting)
        drawSelectionCursor(cm, range, curFragment);
      if (!collapsed)
        drawSelectionRange(cm, range, selFragment);
    }

    // Move the hidden textarea near the cursor to prevent scrolling artifacts
    if (cm.options.moveInputWithCursor) {
      var headPos = cursorCoords(cm, doc.sel.primary().head, "div");
      var wrapOff = display.wrapper.getBoundingClientRect(), lineOff = display.lineDiv.getBoundingClientRect();
      var top = Math.max(0, Math.min(display.wrapper.clientHeight - 10,
                                     headPos.top + lineOff.top - wrapOff.top));
      var left = Math.max(0, Math.min(display.wrapper.clientWidth - 10,
                                      headPos.left + lineOff.left - wrapOff.left));
      display.inputDiv.style.top = top + "px";
      display.inputDiv.style.left = left + "px";
    }

    removeChildrenAndAdd(display.cursorDiv, curFragment);
    removeChildrenAndAdd(display.selectionDiv, selFragment);
  }

  // Draws a cursor for the given range
  function drawSelectionCursor(cm, range, output) {