<iframe 
    src="http://jsxgraph.org/share/iframe/curly-brackets" 
    style="border: 1px solid black; overflow: hidden; width: 550px; aspect-ratio: 55 / 65;" 
    name="JSXGraph example: Curly brackets" 
    allowfullscreen
></iframe>

<div id="board-0-wrapper" class="jxgbox-wrapper " style="width: 100%; ">
   <div id="board-0" class="jxgbox" style="aspect-ratio: 1 / 1; width: 100%;" data-ar="1 / 1"></div>
</div>

<script type = "text/javascript"> 
    /*
    This example is licensed under a 
    Creative Commons Attribution 4.0 International License.
    https://creativecommons.org/licenses/by/4.0/
    
    Please note you have to mention 
    The Center of Mobile Learning with Digital Technology
    in the credits.
    */
    
    const BOARDID = 'board-0';

    const board = JXG.JSXGraph.initBoard(BOARDID, {boundingbox:[-4,4,4,-4], keepaspectratio:true, axis:true});
    
    var A = board.create('point', [-3,3]);
    var B = board.create('point', [3,-2]);
    var line = board.create('segment', [A,B]);
    
    var height = 0.5; // height of the curly bracket
    
    // Build the curly bracket
    var crl = board.create('curve', [[0],[0]], {strokeWidth:1, strokeColor:'black'});
    crl.bezierDegree = 3;
    
    crl.updateDataArray = function() {
        var d = [B.X() - A.X(), B.Y() - A.Y()],
            dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
            mid = [(A.X() + B.X()) * 0.5, (A.Y() + B.Y()) * 0.5];
    
        d[0] *= height / dl;
        d[1] *= height / dl;
    
        this.dataX = [ A.X(), A.X() - d[1], mid[0], mid[0] - d[1], mid[0], B.X() - d[1], B.X() ];
        this.dataY = [ A.Y(), A.Y() + d[0], mid[1], mid[1] + d[0], mid[1], B.Y() + d[0], B.Y() ];
    };
    
    // Text
    var txt = board.create('text', [
                        function() { 
                            var d = [B.X() - A.X(), B.Y() - A.Y()],
                                dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
                                mid = (A.X() + B.X()) * 0.5;
    
                            d[1] *= height / dl;
                            return mid - d[1] + 0.1; 
                        },
                        function() { 
                            var d = [B.X() - A.X(), B.Y() - A.Y()],
                                dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
                                mid = (A.Y() + B.Y()) * 0.5;
    
                            d[0] *= height / dl;
                            return mid + d[0] + 0.1; 
                        },
                        () => 'length=' + B.Dist(A).toFixed(2)
                    ]);
    
    
    board.update(); // This update is necessary to call updateDataArray the first time.
 </script> 

<jsxgraph width="100%" aspect-ratio="1 / 1" title="Curly brackets" description="This construction was copied from JSXGraph examples database: BTW HERE SHOULD BE A GENERATED LINKuseGlobalJS="false">
   /*
   This example is licensed under a 
   Creative Commons Attribution 4.0 International License.
   https://creativecommons.org/licenses/by/4.0/
   
   Please note you have to mention 
   The Center of Mobile Learning with Digital Technology
   in the credits.
   */
   
   const board = JXG.JSXGraph.initBoard(BOARDID, {boundingbox:[-4,4,4,-4], keepaspectratio:true, axis:true});
   
   var A = board.create('point', [-3,3]);
   var B = board.create('point', [3,-2]);
   var line = board.create('segment', [A,B]);
   
   var height = 0.5; // height of the curly bracket
   
   // Build the curly bracket
   var crl = board.create('curve', [[0],[0]], {strokeWidth:1, strokeColor:'black'});
   crl.bezierDegree = 3;
   
   crl.updateDataArray = function() {
       var d = [B.X() - A.X(), B.Y() - A.Y()],
           dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
           mid = [(A.X() + B.X()) * 0.5, (A.Y() + B.Y()) * 0.5];
   
       d[0] *= height / dl;
       d[1] *= height / dl;
   
       this.dataX = [ A.X(), A.X() - d[1], mid[0], mid[0] - d[1], mid[0], B.X() - d[1], B.X() ];
       this.dataY = [ A.Y(), A.Y() + d[0], mid[1], mid[1] + d[0], mid[1], B.Y() + d[0], B.Y() ];
   };
   
   // Text
   var txt = board.create('text', [
                       function() { 
                           var d = [B.X() - A.X(), B.Y() - A.Y()],
                               dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
                               mid = (A.X() + B.X()) * 0.5;
   
                           d[1] *= height / dl;
                           return mid - d[1] + 0.1; 
                       },
                       function() { 
                           var d = [B.X() - A.X(), B.Y() - A.Y()],
                               dl = Math.sqrt(d[0] * d[0] + d[1] * d[1]),
                               mid = (A.Y() + B.Y()) * 0.5;
   
                           d[0] *= height / dl;
                           return mid + d[0] + 0.1; 
                       },
                       () => 'length=' + B.Dist(A).toFixed(2)
                   ]);
   
   
   board.update(); // This update is necessary to call updateDataArray the first time.
</jsxgraph>