translate.js Example File | Qt Script

Qt 5.9 | Qt Script | Context2D Example | translate.js Example File

Qt 5.9.3 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();
      }