Element.truncate.js

Element.implement({
	
	truncate : function(len,str,mid){
		var str = str || '...'; 
		var mid = !!mid; 
		var w = this.getSize().x;
		if( w < len) return this;
		
		var txt = this.get('text');
		var char_size = Math.ceil(w / txt.length);
		var keep = Math.ceil(len / char_size) - str.length;
		
		if(mid) this.set('text', txt.slice(0,keep/2) + str + txt.slice(txt.length - keep/2) );
		else this.set('text', txt.slice(0,keep) + str);
		var w = this.getSize().x;	
		
		while(w > len || ((len-w) > char_size*2)){
			char_size = Math.ceil(w / keep);
			var take = Math.floor((len - w) / char_size);
			keep += take;
			
			if(mid) this.set('text', txt.slice(0,keep/2) + str + txt.slice(txt.length - keep/2) );
			else this.set('text', txt.slice(0,keep) + str);
			w = this.getSize().x;
		}
		return this;
	}
});