Qt Reference Documentation

# translate.js Example File

script/context2d/scripts/translate.js

       var ctx = document.getElementById('tutorial').getContext('2d');
       ctx.fillRect(0,0,300,300);
       for (var i=0;i<3;i++) {
         for (var j=0;j<3;j++) {
           ctx.save();
           ctx.strokeStyle = "#9CFF00";
           ctx.translate(50+j*100,50+i*100);
           drawSpirograph(ctx,20*(j+2)/(j+1),-8*(i+3)/(i+1),10);
           ctx.restore();
         }
       }

     function drawSpirograph(ctx,R,r,O){
       var x1 = R-O;
       var y1 = 0;
       var i  = 1;
       ctx.beginPath();
       ctx.moveTo(x1,y1);
       do {
         if (i>20000) break;
         var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72))
         var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72))
         ctx.lineTo(x2,y2);
         x1 = x2;
         y1 = y2;
         i++;
       } while (x2 != R-O && y2 != 0 );
       ctx.stroke();
     }