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require File.dirname(__FILE__) + '/base'
##
# Here's how to make a Pie graph:
#
# g = Gruff::Pie.new
# g.title = "Visual Pie Graph Test"
# g.data 'Fries', 20
# g.data 'Hamburgers', 50
# g.write("test/output/pie_keynote.png")
#
# To control where the pie chart starts creating slices, use #zero_degree.
class Gruff::Pie < Gruff::Base
TEXT_OFFSET_PERCENTAGE = 0.15
# Can be used to make the pie start cutting slices at the top (-90.0)
# or at another angle. Default is 0.0, which starts at 3 o'clock.
attr_accessor :zero_degree
# Do not show labels for slices that are less than this percent. Use 0 to always show all labels.
# Defaults to 0
attr_accessor :hide_labels_less_than
def initialize_ivars
super
@zero_degree = 0.0
@hide_labels_less_than = 0.0
end
def draw
@hide_line_markers = true
super
return unless @has_data
diameter = @graph_height
radius = ([@graph_width, @graph_height].min / 2.0) * 0.8
top_x = @graph_left + (@graph_width - diameter) / 2.0
center_x = @graph_left + (@graph_width / 2.0)
center_y = @graph_top + (@graph_height / 2.0) - 10 # Move graph up a bit
total_sum = sums_for_pie()
prev_degrees = @zero_degree
# Use full data since we can easily calculate percentages
data = (@sort ? @data.sort{ |a, b| a[DATA_VALUES_INDEX].first <=> b[DATA_VALUES_INDEX].first } : @data)
data.each do |data_row|
if data_row[DATA_VALUES_INDEX].first > 0
@d = @d.stroke data_row[DATA_COLOR_INDEX]
@d = @d.fill 'transparent'
@d.stroke_width(radius) # stroke width should be equal to radius. we'll draw centered on (radius / 2)
current_degrees = (data_row[DATA_VALUES_INDEX].first / total_sum) * 360.0
# ellipse will draw the the stroke centered on the first two parameters offset by the second two.
# therefore, in order to draw a circle of the proper diameter we must center the stroke at
# half the radius for both x and y
@d = @d.ellipse(center_x, center_y,
radius / 2.0, radius / 2.0,
prev_degrees, prev_degrees + current_degrees + 0.5) # <= +0.5 'fudge factor' gets rid of the ugly gaps
half_angle = prev_degrees + ((prev_degrees + current_degrees) - prev_degrees) / 2
label_val = ((data_row[DATA_VALUES_INDEX].first / total_sum) * 100.0).round
unless label_val < @hide_labels_less_than
# End the string with %% to escape the single %.
# RMagick must use sprintf with the string and % has special significance.
label_string = label_val.to_s + '%%'
@d = draw_label(center_x,center_y, half_angle,
radius + (radius * TEXT_OFFSET_PERCENTAGE),
label_string)
end
prev_degrees += current_degrees
end
end
# TODO debug a circle where the text is drawn...
@d.draw(@base_image)
end
private
##
# Labels are drawn around a slightly wider ellipse to give room for
# labels on the left and right.
def draw_label(center_x, center_y, angle, radius, amount)
# TODO Don't use so many hard-coded numbers
r_offset = 20.0 # The distance out from the center of the pie to get point
x_offset = center_x # + 15.0 # The label points need to be tweaked slightly
y_offset = center_y # This one doesn't though
radius_offset = (radius + r_offset)
ellipse_factor = radius_offset * 0.15
x = x_offset + ((radius_offset + ellipse_factor) * Math.cos(angle.deg2rad))
y = y_offset + (radius_offset * Math.sin(angle.deg2rad))
# Draw label
@d.fill = @font_color
@d.font = @font if @font
@d.pointsize = scale_fontsize(@marker_font_size)
@d.stroke = 'transparent'
@d.font_weight = BoldWeight
@d.gravity = CenterGravity
@d.annotate_scaled( @base_image,
0, 0,
x, y,
amount, @scale)
end
def sums_for_pie
total_sum = 0.0
@data.collect {|data_row| total_sum += data_row[DATA_VALUES_INDEX].first }
total_sum
end
end
class Float
# Used for degree => radian conversions
def deg2rad
self * (Math::PI/180.0)
end
end
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