waving flag waving flag - html5-canvas

Question

<script type="text/javascript">
canvas.onmouseover = function onMouseover(e) {
waveFlag( flag, 20, 10, 150, 200, -0.1 );
}
canvas.onmouseout = function onMouseover(e) {
}
</script>
Above code is when the mouse move to the flag the flag will waving, how can i stop waving the flag when mouse out???

Answer 1

Just stop the setInterval from firing and the function will stop
<script type="text/javascript">
var timer = null;
function waveFlag( canvas, wavelength, amplitude, period, shading, squeeze ) {
if (!squeeze) squeeze = 0;
if (!shading) shading = 100;
if (!period) period = 200;
if (!amplitude) amplitude = 10;
if (!wavelength) wavelength = canvas.width/10;
var fps = 30;
var ctx = canvas.getContext('2d');
var w = canvas.width, h = canvas.height;
var od = ctx.getImageData(0,0,w,h).data;
// var ct = 0, st=new Date;
return setInterval(function(){
var id = ctx.getImageData(0,0,w,h);
var d = id.data;
var now = (new Date)/period;
for (var y=0;y<h;++y){
var lastO=0,shade=0;
var sq = (y-h/2)*squeeze;
for (var x=0;x<w;++x){
var px = (y*w + x)*4;
var pct = x/w;
var o = Math.sin(x/wavelength-now)*amplitude*pct;
var y2 = y + (o+sq*pct)<<0;
var opx = (y2*w + x)*4;
shade = (o-lastO)*shading;
d[px ] = od[opx ]+shade;
d[px+1] = od[opx+1]+shade;
d[px+2] = od[opx+2]+shade;
d[px+3] = od[opx+3];
lastO = o;
}
}
ctx.putImageData(id,0,0);
// if ((++ct)%100 == 0) console.log( 1000 * ct / (new Date - st));
},1000/fps);
}
var canvas = document.getElementById("flag");
canvas.onmouseover = function onMouseover(e) {
timer = waveFlag( flag, 20, 10, 150, 200, -0.1 );
}
canvas.onmouseout = function onMouseover(e) {
window.clearInterval(timer);
timer = null;
}
</script>