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Contents
# A wrapper around the google charts service.
# TODO consider making generic and open sourcing
class GooglePieChart
attr_accessor :width, :height, :color
def initialize
# an array of [label, value]
@data = []
self.width = 300
self.height = 200
end
def add_data_point(label, value)
@data << [label, value]
@max = (@max.nil? || @max < value ? value : @max)
end
# render the chart to html by creating an image object and
# placing the correct URL to the google charts api
def render
labels = ''
values = ''
@data.each do |label, value|
labels << CGI::escape(label) + '|'
values << (value * 100 / @max).round.to_s + ","
end
# strip of the last separator char for labels and values
labels = labels[0..-2]
values = values[0..-2]
params = {:cht => 'p', :chs => "#{width}x#{height}", :chd => "t:#{values}", :chl => labels }
params['chco'] = color if color
url = "http://chart.apis.google.com/chart?#{to_query(params)}"
alt_msg = "This pie chart is generated by Google Charts. You must be connected to the Internet to view this chart."
html = "<img id=\"pie_chart_image\" src=\"#{url}\" alt=\"#{alt_msg}\"/>"
return html
end
private
# Hash#to_query is not present in all supported rails platforms, so implement
# its equivalent here.
def to_query(params)
p = []
params.each do |k,v|
p << "#{k}=#{v}"
end
p.join "&"
end
end
Version data entries
20 entries across 20 versions & 2 rubygems