Images

From JSXGraph Wiki
Jump to: navigation, search

Static image

The JavaScript code

Images can be included with the command

var im = brd.create('image',[urlImg, [-1,-1], [3,3] ]);

It has the parameters:

  • urlImage: URL of the image. Data URLs are possible, but will not beshown in the Internet Explorer <8 and are restricted to max. 32kByte in the Internet Explorer 8.
  • [x,y]: position of the lower left corner of the image.
  • [w,h]: width and height of the image.
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,5,5,-5],axis:true});
var urlImg = "http://jsxgraph.uni-bayreuth.de/distrib/images/uccellino.jpg";
var im = brd.create('image',[urlImg, [-1,-1], [3,3] ]);

Dynamic image I

The JavaScript code

The parameters

  • urlImage
  • [x,y]
  • [w,h]

can be given by functions. Here is an example where the position of the image depends on the position of the point "A".

  var brd = JXG.JSXGraph.initBoard('box2', {boundingbox:[-5,5,5,-5],axis:true});
  var p = brd.create('point',[-1,-1], {size:10, opacity:0.3});
  var urlImg = "http://jsxgraph.uni-bayreuth.de/distrib/images/uccellino.jpg";
  var im = brd.create('image',[urlImg, [function(){return p.X();},function(){return p.Y();}], [3,3] ]);

Dynamic image II

The following example is even more dyanmic. If the position of the point "A"s changed, the image not only follows but also the image itself changes and the opcity.

The JavaScript code

  var brd = JXG.JSXGraph.initBoard('box3', {boundingbox:[-5,5,5,-5],axis:true});
  var p = brd.create('point',[-1,0], {size:10, opacity:0.3});
  var urlImg1 = "http://jsxgraph.uni-bayreuth.de/distrib/images/fagiolo.jpg";
  var urlImg2 = "http://jsxgraph.uni-bayreuth.de/distrib/images/perched_birds.jpg";
  var im = brd.create('image',
          [
            function(){if (p.X()<0) { return urlImg1; } else { return urlImg2; } },   // Make the image url dynamic
            [function(){return p.X();},function(){return p.Y();}], [2*1.61,2]         // Make the image position dynamic
          ],
          { opacity: function(){ return 2.0/Math.exp(Math.abs(p.Y()));} }             // Make the opacity dynamic
          );

Rotated image

Rotate image around its lower left corner.

The JavaScript code

  var brd = JXG.JSXGraph.initBoard('box4', {boundingbox:[-5,5,5,-5],axis:true});
  var urlImg1 = "http://jsxgraph.uni-bayreuth.de/distrib/images/uccellino.jpg";
  var im = brd.create('image',
          [urlImg1, [0, 0], [3, 3]],
          { opacity: 0.4 }             // original position
          ); 
  var im1 = brd.create('image',
          [urlImg1, [0, 0], [3, 3]],
          { opacity: 0.6, rotate: 30 }             // rotate by 30°
          );

Rotate image around its center

Rotate image around its center. This has to be realized with transformations, see Texts and Transformations II.

The JavaScript code

  var brd = JXG.JSXGraph.initBoard('box5', {boundingbox:[-5,5,5,-5],axis:true});
  var urlImg1 = "http://jsxgraph.uni-bayreuth.de/distrib/images/uccellino.jpg";
  var im = brd.create('image',
          [urlImg1, [-3, 0], [3, 3]],
          { opacity: 0.4 }             // original position
          ); 
  var im1 = brd.create('image',
          [urlImg1, [-3, 0], [3, 3]],
          { opacity: 0.6 }            
          ); 

  var tOff = brd.create('transform', [
                    function () {
                        return -im1.X() - im1.W()*0.5;
                    }, function () {
                        return -im1.Y() - im1.H()*0.5;
                    }
                ], {type: 'translate'});
  var tOffInverse = brd.create('transform', [
                    function () {
                        return im1.X() + im1.W()*0.5;
                    }, function () {
                        return im1.Y() + im1.H()*0.5;
                    }
                ], {type: 'translate'});
  var tRot = brd.create('transform', [
                    60 * Math.PI / 180.0        // Rotate by 60°
                ], {type: 'rotate'});



  tOff.bindTo(im1);        // Shift image to origin
  tRot.bindTo(im1);        // Rotate
  tOffInverse.bindTo(im1); // Shift image back

  brd.update();