canvas-feedback-1k.js

k=c;c=document.getElementsByTagName('canvas')[0];
c.width=c.clientWidth/4;c.height=c.clientHeight/4;
r=0;s=1;n=40;
cw=c.width;cx=cw/2;
ch=c.height;cy=ch/2;
d=cw/60;
omd=function(e){px=e.pageX;py=e.pageY;d=1;};
b.onmousedown=omd;
b.addEventListener('touchstart',function(e){omd(e.touches[0]);});
omm=function(e){if(d){cx+=(e.pageX-px)/200;cy+=(e.pageY-py)/200;}};
b.onmousemove=omm;
b.addEventListener('touchmove',function(e){omm(e.touches[0]);});
omu=function(){d=0;};
b.onmouseup=omu;
b.addEventListener('touchend',omu);
k.fillStyle="white";
k.fillRect(0,0,cw,ch);
k.fillStyle="black";
for(i=0;i<n;i++) {
 k.save();
 k.translate(cx,cy);
 k.rotate(((Math.PI*2)/n)*i);
 k.beginPath();
 k.moveTo(0,0);
 k.lineTo(-d,cw);
 k.lineTo(+d,cw);
 k.lineTo(0,0);
 k.fill();
 k.restore();
}
s=1;d=0;
setInterval(function(){
 k.save();
 k.translate(cx,cy);
 k.rotate(r);
 k.translate(-cx,-cy);
 r+=0.0005;
 k.drawImage(c,s,s,cw-s-s,ch-s-s);
 k.restore();
},30);