CFLib.org – Common Function Library Project

Description:
Allows you to assign colors. The value is compared to a range of passed in values and the element is assigned a "heat" color based on its derived value's position within the range. (Useful in non-javascript environments or calculating charting colors.) Based on HeatColor jQuery plugin http://www.jnathanson.com/blog/client/jquery/heatcolor/

Return Values:
Returns a string.

Example:

<cfoutput>
<cfloop from="1" to="80" index="this">
<cfset c = heatColor(this,0,80,"roygbiv",0.75,1)>
<div style="background-color:#c#">#c#</div>
</cfloop>
</cfoutput>

Parameters:

Full UDF Source:

/**
 * Assign a "heat" color based on value's position within the range.
 * 
 * @param num      Value to check. (Required)
 * @param minVal      Minimum value. Defaults to 1. (Optional)
 * @param maxVal      Maximum value. Defaults to 100. (Optional)
 * @param colorStyle      Either roygiv or greentored. Defaults to greentored. (Optional)
 * @param lightness      Lightness of color. 0 is darkest, 0.9 is lightest. Defaults to 0. (Optional)
 * @param reverseOrder      Colors will go highest to lowest unless this argument is true. Defaults to false. (Optional)
 * @return Returns a string. 
 * @author James Moberg (james@ssmedia.com) 
 * @version 1, August 5, 2011 
 */
function heatColor(num) {
    var minval = 1;
    var maxval = 100;
    var colorStyle = 'greentored'; //roygbiv OR greentored
    var lightness = 0;  //sets lightness of color - 0 is darkest, 0.9 is lightest
    var reverseOrder = 0; // By default the values will be colored highest to lowest; set this to true to color lowest to highest 
    var position = 0;
    var x = 0;
    var R = "";
    var G = "";
    var B = "";
    var shft = 0;
    if(ArrayLen(arguments) GTE 2 AND isnumeric(arguments[2])) {
        minval = val(arguments[2]);
    }
    if(ArrayLen(arguments) GTE 3 AND val(arguments[3])) {
        maxval = val(arguments[3]);
    }
    if(ArrayLen(arguments) GTE 4 AND arguments[4] IS 'roygbiv') {
        colorStyle = arguments[4];
    }
    if(ArrayLen(arguments) GTE 5 AND val(arguments[5]) GTE 0 AND val(arguments[5]) LTE 0.9) {
        lightness = val(arguments[5]);
    }
    if(ArrayLen(arguments) GTE 6 AND val(arguments[6])) {
        reverseOrder = YesNoFormat(1);
    }
    if (reverseOrder){
        x = minval;
        minval = maxval;
        maxval = x;
    }
    position = (num - minval) / (maxval - minval);
    shft = position + 0.2 + 5.5*(1-position);
    if (colorStyle IS 'roygbiv'){
        shft = 0.5*position + 1.7*(1-position);
    }
    x = shft + position * (2*Pi());    
    if (colorStyle NEQ 'roygbiv'){    
        x = x * -1;
    }
    R = INT((cos(x) + 1) * 128);
    R = Ucase(FormatBaseN(INT(R + lightness * (256 - R)),16));
    if (Len(R) IS 1){ R = "0" & R;}
    
    G = INT((cos(x+Pi()/2) + 1) * 128);
    G = Ucase(FormatBaseN(INT(G + lightness * (256 - G)),16));
    if (Len(G) IS 1){ G = "0" & G;}
    
    B = INT((cos(x+Pi()) + 1) * 128);
    B = Ucase(FormatBaseN(INT(B + lightness * (256 - B)),16));
    if (Len(B) IS 1){ B = "0" & B;}
    
    return '##' & R & G & B;
}