// Create some free points. e.g. A, B, C, D
 // Create a group

 var p, col, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));
 g = board.create('group', p);

 // Create some free points. e.g. A, B, C, D
 // Create a group
 // If the points define a polygon and the polygon has the attribute hasInnerPoints:true,
 // the polygon can be dragged around.

 var p, col, pol, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));

 pol = board.create('polygon', p, {hasInnerPoints: true});
 g = board.create('group', p);

 // Allow rotations:
 // Define a center of rotation and declare points of the group as "rotation points".

 var p, col, pol, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));

 pol = board.create('polygon', p, {hasInnerPoints: true});
 g = board.create('group', p);
 g.setRotationCenter(p[0]);
 g.setRotationPoints([p[1], p[2]]);

 // Allow rotations:
 // As rotation center, arbitrary points, coordinate arrays,
 // or functions returning coordinate arrays can be given.
 // Another possibility is to use the predefined string 'centroid'.

 // The methods to define the rotation points can be chained.

 var p, col, pol, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));

 pol = board.create('polygon', p, {hasInnerPoints: true});
 g = board.create('group', p).setRotationCenter('centroid').setRotationPoints([p[1], p[2]]);

 // Allow scaling:
 // As for rotation one can declare points of the group to trigger a scaling operation.
 // For this, one has to define a scaleCenter, in analogy to rotations.

 // Here, the yellow  point enables scaling, the red point a rotation.

 var p, col, pol, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:'yellow', fillColor:'yellow'}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));

 pol = board.create('polygon', p, {hasInnerPoints: true});
 g = board.create('group', p).setRotationCenter('centroid').setRotationPoints([p[2]]);
 g.setScaleCenter(p[0]).setScalePoints(p[1]);

 // Allow Translations:
 // By default, every point of a group triggers a translation.
 // There may be situations, when this is not wanted.

 // In this example, E triggers nothing, but itself is rotation center
 // and is translated, if other points are moved around.

 var p, q, col, pol, g;
 col = 'blue';
 p = [];
 p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
 p.push(board.create('point',[2, -1 ], {size: 5, strokeColor:'yellow', fillColor:'yellow'}));
 p.push(board.create('point',[2, 1 ], {size: 5, strokeColor:'red', fillColor:'red'}));
 p.push(board.create('point',[-2, 1], {size: 5, strokeColor:col, fillColor:col}));
 q = board.create('point',[0, 0], {size: 5, strokeColor:col, fillColor:col});

 pol = board.create('polygon', p, {hasInnerPoints: true});
 g = board.create('group', p.concat(q)).setRotationCenter('centroid').setRotationPoints([p[2]]);
 g.setScaleCenter(p[0]).setScalePoints(p[1]);
 g.removeTranslationPoint(q);

       // Add an image and use the group tools to manipulate it
      let urlImg = "https://jsxgraph.org/distrib/images/uccellino.jpg";
      let lowleft = [-2, -1]

      let col = 'blue';
      let p = [];
      p.push(board.create('point', lowleft, { size: 5, strokeColor: col, fillColor: col }));
      p.push(board.create('point', [2, -1], { size: 5, strokeColor: 'yellow', fillColor: 'yellow', name: 'scale' }));
      p.push(board.create('point', [2, 1], { size: 5, strokeColor: 'red', fillColor: 'red', name: 'rotate' }));
      p.push(board.create('point', [-2, 1], { size: 5, strokeColor: col, fillColor: col, name: 'translate' }));

      let im = board.create('image', [urlImg, lowleft, [2, 2]]);
      let pol = board.create('polygon', p, { hasInnerPoints: true });

      let g = board.create('group', p.concat(im))
      // g.addPoint(im)   // image, but adds as a point

      g.setRotationCenter(lowleft)
      g.setRotationPoints([p[2]]);

      g.setScaleCenter(p[0]).setScalePoints(p[1]);