/******************************************************************

   WarpGear JavaScript Fader v1.0 
   Copyright © 2001 WarpGear Software
   
   web: http://www.warpgear.com
   email: jsfader@warpgear.com (suggestions & bugreports)
   author: Tom Kalmijn

   These scripts, referred to as 'the program', are freeware! The 
   program may be used freely by any individual or organization for 
   both non-commercial and commercial purposes.

   You are encouraged to distribute the program to your friends and 
   colleagues but only *in its unaltered form*. 

   The distributable package consists of a zip archive with these 
   two files: fader.js (this file) and demo.html

   Note:
   To configure Fader you typically need not alter this file. 
   See demo.html for configuration instructions.

******************************************************************/

var colors = new Array(steps);
getFadeColors(bgcolor,fcolor,colors);
var color = 0;
var text = 0;
var step = 1;

// fade: magic fader function
function fade()
{
	// insert fader color into message
	var text_out = texts[text].replace("{COLOR}", colors[color]); // texts should be defined in user script, e.g.: var texts = new Array("<font color='{COLOR}' sized='+3' face='Arial'>howdy</font>");

    // actually write message to document
	htmlWrite(text_out, "fader");
	
	// select next fader color
	color += step; 
	
	// completely faded in?
	if (color >= colors.length-1) 
	{ 
		step = -1; // traverse colors array backward to fade out
		
		// stop at last message if loop=false
		if (!loop && text >= texts.length-1) return; // loop should be defined in user script, e.g.: var loop=true;
	}
	
	// completely faded out?
	if (color == 0)
	{
		step = 1; // traverse colors array forward to fade in again
		
		// select next message
		text += 1;
		if (text == texts.length) text = 0; // loop back to first message
	}
	
	// subtle timing logic...
	setTimeout("fade()", (color == colors.length-2 && step == -1) ? show : ((color == 1 && step == 1) ? sleep : 50)); // sleep and show should be defined in user script, e.g.: var sleep=30; var show=500;
}

// helper function to make fader cross browser compatible
function htmlWrite(html,id)
{
	var obj;
	if (document.getElementById) // IE 5+ & Netscape 6+
	{
		obj = document.getElementById(id);
		obj.innerHTML = html;
	}
	else if (document.all) // IE 4+
	{
		obj = document.all[id];
		obj.innerHTML = html;
	}
	else if (document.layers) // Netscape 4+
	{
		obj = document.layers[id];
		obj.document.open();
		obj.document.write(html);
		obj.document.close();
	}
}

// getFadeColors: fills Colors (predefined Array)
// with color hex strings fading from ColorA to ColorB
// note: Colors.length equals the number of steps to fade
function getFadeColors(ColorA, ColorB, Colors)
{
	len = Colors.length; 
	
	// strip '#' signs if present 
	if (ColorA.charAt(0)=='#') ColorA = ColorA.substring(1);
	if (ColorB.charAt(0)=='#') ColorB = ColorB.substring(1);

	// substract rgb compents from hex string 
	var r = HexToInt(ColorA.substring(0,2));
	var g = HexToInt(ColorA.substring(2,4));
	var b = HexToInt(ColorA.substring(4,6));
	var r2 = HexToInt(ColorB.substring(0,2));
	var g2 = HexToInt(ColorB.substring(2,4));
	var b2 = HexToInt(ColorB.substring(4,6));

	// calculate size of step for each color component
	var rStep = Math.round((r2 - r) / len);
	var gStep = Math.round((g2 - g) / len);
	var bStep = Math.round((b2 - b) / len);
	
	// fill Colors array with fader colors
	for (i = 0; i < len-1; i++)
	{
		Colors[i] = "#" + IntToHex(r) + IntToHex(g) + IntToHex(b);
		r += rStep;
		g += gStep;
		b += bStep;
	}
	Colors[len-1] = "#" + ColorB; // make sure we finish exactly at ColorB
}

// IntToHex: converts integers between 0-255 into a two digit hex string.
function IntToHex(n) 
{
	var result = n.toString(16);
	if (result.length==1) result = "0"+result;
	return result;
}

// HexToInt: converts two digit hex strings into integer.
function HexToInt(hex) 
{
	return parseInt(hex, 16); 
}