var pictureSrc = 'style_images/snow.gif'; //the location of the snowflakes
var pictureWidth = 13;                    //the width of the snowflakes
var pictureHeight = 13;                   //the height of the snowflakes
var numFlakes = 7;                        //the number of snowflakes
var downSpeed = 0.003;                    //the falling speed of snowflakes (portion of screen per 100 ms)
var lrFlakes = 3;                         //the speed that the snowflakes should swing from side to side
                                          //relative to distance fallen (swing increases with fewer
                                          //snowflakes to fill available space)
var snowEnabled = false;                  //true+false
var intervalID = 0;

/****** Do not edit below this line unless you know what you are doing ******/

//safety checks. Browsers will hang if this is wrong. If other values are wrong there will just be errors
if( typeof( numFlakes ) != 'number' || Math.round( numFlakes ) != numFlakes || numFlakes < 1 ) { numFlakes = 10; }

//draw the snowflakes
for( var x = 0; x < numFlakes; x++ ) {
        if( document.layers ) { //releave NS4 bug
                document.write('<layer id="snFlkDiv'+x+'"><img src="'+pictureSrc+'" height="'+pictureHeight+'" width="'+pictureWidth+'" alt="*" border="0" onclick="StopSnow()"></layer>');
        } else {
                document.write('<div style="position:absolute;" id="snFlkDiv'+x+'"><img src="'+pictureSrc+'" height="'+pictureHeight+'" width="'+pictureWidth+'" alt="*" border="0" onclick="StopSnow()"></div>');
        }
}

//calculate initial positions (in portions of browser window size)
var xcoords = new Array(), ycoords = new Array(), snFlkTemp;
for( var x = 0; x < numFlakes; x++ ) {
        xcoords[x] = ( x + 1 ) / ( numFlakes + 1 );
        do { snFlkTemp = Math.round( ( numFlakes - 1 ) * Math.random() );
        } while( typeof( ycoords[snFlkTemp] ) == 'number' );
        ycoords[snFlkTemp] = x / numFlakes;
}

//now animate
function flakeFall() {
        if( !snowEnabled )
        {
                window.clearInterval(intervalID);
                for( var x = 0; x < numFlakes; x++ )
                {
                        var divRef = getRefToDivNest('snFlkDiv'+x); if( !divRef ) { return; }
                        if( divRef.style ) { divRef = divRef.style; }
                        divRef.visibility = 'hidden';
                }
                return;
        }
        if( !getRefToDivNest('snFlkDiv0') ) { return; }
        var scrWidth = 0, scrHeight = 0, scrollHeight = 0, scrollWidth = 0;
        //find screen settings for all variations. doing this every time allows for resizing and scrolling
        if( typeof( window.innerWidth ) == 'number' ) { scrWidth = window.innerWidth; scrHeight = window.innerHeight; } else {
                if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
                        scrWidth = document.documentElement.clientWidth; scrHeight = document.documentElement.clientHeight; } else {
                        if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
                                scrWidth = document.body.clientWidth; scrHeight = document.body.clientHeight; } } }
        if( typeof( window.pageYOffset ) == 'number' ) { scrollHeight = pageYOffset; scrollWidth = pageXOffset; } else {
                if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) { scrollHeight = document.body.scrollTop; scrollWidth = document.body.scrollLeft; } else {
                        if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) { scrollHeight = document.documentElement.scrollTop; scrollWidth = document.documentElement.scrollLeft; } }
        }
        //move the snowflakes to their new position
        for( var x = 0; x < numFlakes; x++ ) {
                if( ycoords[x] * scrHeight > scrHeight - pictureHeight ) { ycoords[x] = 0; }
                var divRef = getRefToDivNest('snFlkDiv'+x); if( !divRef ) { return; }
                if( divRef.style ) { divRef = divRef.style; } var oPix = document.childNodes ? 'px' : 0;
                divRef.top = ( Math.round( ycoords[x] * scrHeight ) + scrollHeight ) + oPix;
                divRef.left = ( Math.round( ( ( xcoords[x] * scrWidth ) - ( pictureWidth / 2 ) ) + ( ( scrWidth / ( ( numFlakes + 1 ) * 4 ) ) * ( Math.sin( lrFlakes * ycoords[x] ) - Math.sin( 3 * lrFlakes * ycoords[x] ) ) ) ) + scrollWidth ) + oPix;
                ycoords[x] += downSpeed;
        }
}

//DHTML handlers
function getRefToDivNest(divName) {
        if( document.layers ) { return document.layers[divName]; } //NS4
        if( document[divName] ) { return document[divName]; } //NS4 also
        if( document.getElementById ) { return document.getElementById(divName); } //DOM (IE5+, NS6+, Mozilla0.9+, Opera)
        if( document.all ) { return document.all[divName]; } //Proprietary DOM - IE4
        return false;
}

function StopSnow()
{
        snowEnabled = false;
}

intervalID = window.setInterval('flakeFall();',40);