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Using Nick Coloring in Styles

The first Colloquy style to use this technique, which assigns a different color to messages from each nick in a chat room, was "DecafBland", by Les Orchard. Others styles such as Frugal and Lancia use this technique. The technique is fairly straightforward; the trick lies in mapping each nick to a reasonably unique style name. The Frugal style maps hostmasks, since they are usually more unique and give better results.

The mapping from nick to style is most easily done with a hash function. Les Orchard came up with the following (this should appear in the style's XSL file):

<xsl:variable name="senderNick" select="sender | ../sender"/>
<xsl:variable name="senderHash"
	select="number(translate($senderNick,
		'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM-_^[]{}|',
		'123456789012345678901234567890123456789012345678901234567890'
	))"
/>

<xsl:variable name="senderColor">
	<xsl:choose>
	<xsl:when test="sender/@self = 'yes'">colorself</xsl:when>
	<xsl:when test="../sender/@self = 'yes'">colorself</xsl:when>
	<xsl:when test="string-length(sender/text()) &gt; 0">
	<xsl:value-of select="concat('color', $senderHash mod 15)" />
	</xsl:when>
	</xsl:choose>
</xsl:variable>

(Note: Here I have made slight formatting changes and omitted a few irrelevant bits of code from DecafBland?'s XSL file.)

"senderHash" is created by mapping each letter in the nick to a number. Then, the resulting number is clamped down to a fixed range (in this case, from 0 to 14), and the string "color" is slapped in front of it to yield something like "color11". Later, when the HTML is generated, this string is used as a class, like in the following:

<span id="{@id}" class="{$senderClasses} {$senderColor}">

By styling this class in the CSS file, you can create all sorts of interesting effects on more or less a per-nick basis. Note that since we only generate 15 color classes, it's very likely that more than one nick will map to a single color class. There are two ways to reduce the likelihood of this happing: one is to increase the modulus used to clamp the hash, the other is to use a more sophisticated hashing function. Of course, combining these two approaches is also possible.