line.rb in grosser-db_graph-0.1.5

- old
+ new

@@ -31,11 +31,11 @@
 
     def to_url
       size = @options[:size] || '600x500'
       GoogleChart::LineChart.new(size, nil, false) do |line|
         for name, hash in data
-          line.data(name, self.class.filled_and_sorted_values(hash, x_values), random_color)
+          line.data(name, klass.filled_and_sorted_values(hash, x_values), klass.color_for(name))
         end
         line.axis :x, :labels => x_labels
         line.axis :y, :labels => y_labels
         line.show_legend = (@options[:show_legend]!=false)
       end.to_url
@@ -49,11 +49,11 @@
       end
     end
 
     def y_labels
       values = []
-      data.each{|name,hash|values += self.class.filled_and_sorted_values(hash, x_values)}
+      data.each{|name,hash|values += klass.filled_and_sorted_values(hash, x_values)}
       distribute_evently(values, NUM_Y_LABELS)
     end
 
     def self.url(style, model, attribute, options={})
       g = self.new(style, :at=>options.delete(:at))
@@ -61,10 +61,14 @@
       g.to_url
     end
 
     private
 
+    def klass
+      self.class
+    end
+
     def x_values
       case @style
       when :minutes then 0..59
       when :hours then 0..23
       when :days then 1..31
@@ -72,18 +76,23 @@
       when :months then 1..12
       else raise "#{@style} is not supported"
       end.to_a
     end
 
-    def random_color
-      [1,2,3].map{ (('0'..'9').to_a + ('a'..'f').to_a)[rand(16)] * 2 } * ''
+    #determines a unique color based on a name
+    def self.color_for(name)
+      name = name.inspect + "some randomness for fun"
+      hash = (name.hash % 1_000_000_000).to_s #get a hash of a constant size
+      colors = [hash[0..1], hash[2..3], hash[4..5]].map{|c| c.to_f / 100.0 * 16} #use 3 parts of the hash to get numbers from 0 to 15.99
+      palette = ('0'..'9').to_a + ('a'..'f').to_a #hex values 0..f
+      colors.map{|c| palette[c.floor].to_s * 2} * '' #each color is duplicated and the joined
     end
     
     def interval_for(time)
       interval_word = {:minutes=>:hour,:hours=>:day,:days=>:month,:weeks=>:year,:months=>:year}[@style]
       raise "style #{@style} is not supported" unless interval_word
 
-      start = self.class.at_beginning_of_interval(time, interval_word)
+      start = klass.at_beginning_of_interval(time, interval_word)
       ende = start + 1.send(interval_word) - 1.second
       [start, ende]
     end
 
     def self.at_beginning_of_interval(time, interval_type)
\ No newline at end of file