require("chartdirector")
class VarwidthbarController < ApplicationController
def index()
@title = "Variable Width Bar Chart"
@ctrl_file = File.expand_path(__FILE__)
@noOfCharts = 1
render :template => "templates/chartview"
end
#
# Render and deliver the chart
#
def getchart()
# The data for the chart
data = [800, 600, 1000, 1400]
widths = [250, 500, 960, 460]
labels = ["Wind", "Hydro", "Coal", "Natural Gas"]
# The colors to use
colors = [0x00aa00, 0x66aaee, 0xee6622, 0xffbb00]
# Create a XYChart object of size 500 x 350 pixels
c = ChartDirector::XYChart.new(500, 350)
# Add a title to the chart using 15pt Arial Italic font
c.addTitle("Energy Generation Breakdown", "ariali.ttf", 15)
# Set the plotarea at (60, 60) and of (chart_width - 90) x (chart_height - 100) in size. Use
# a vertical gradient color from light blue (f9f9ff) to sky blue (aaccff) as background. Set
# grid lines to white (ffffff).
plotAreaBgColor = c.linearGradientColor(0, 60, 0, c.getHeight() - 40, 0xaaccff, 0xf9fcff)
c.setPlotArea(60, 60, c.getWidth() - 90, c.getHeight() - 100, plotAreaBgColor, -1, -1,
0xffffff)
# Add a legend box at (50, 30) using horizontal layout and transparent background.
c.addLegend(55, 30, false).setBackground(ChartDirector::Transparent)
# Add titles to x/y axes with 10 points Arial Bold font
c.xAxis().setTitle("Mega Watts", "arialbd.ttf", 10)
c.yAxis().setTitle("Cost per MWh (dollars)", "arialbd.ttf", 10)
# Set the x axis rounding to false, so that the x-axis will fit the data exactly
c.xAxis().setRounding(false, false)
# In ChartDirector, there is no bar layer that can have variable bar widths, but you may
# create a bar using an area layer. (A bar can be considered as the area under a rectangular
# outline.) So by using a loop to create one bar per area layer, we can achieve a variable
# width bar chart.
# starting position of current bar
currentX = 0
0.upto(data.length - 1) do |i|
# ending position of current bar
nextX = currentX + widths[i]
# outline of the bar
dataX = [currentX, currentX, nextX, nextX]
dataY = [0, data[i], data[i], 0]
# create the area layer to fill the bar
layer = c.addAreaLayer(dataY, colors[i], labels[i])
layer.setXData(dataX)
# the ending position becomes the starting position of the next bar
currentX = nextX
end
# Output the chart
send_data(c.makeChart2(ChartDirector::PNG), :type => "image/png", :disposition => "inline")
end
end |