class ChartsController

File: charts_controller.rb
(C): Hipposoft 2008
Purpose: Use the Gruff library to generate charts in PNG format for inclusion in HTML reports.

11-Mar-2008 (ADH): Created.

Public Instance Methods

show() click to toggle source

Show a graph. See charts_helper.rb for the way to generate a URL that will correctly convey the required parameters. Essentially, the ID is used to carry the chart type and extra query string parameters carry additional required parameters. This is more of a ‘create’ action than ‘show’, but since it’s used for things like showing reports and the charts are usually generated on-demand as part of IMG tags, it is far more natural from the caller’s perspective to use ‘show’.

# File app/controllers/charts_controller.rb, line 21
def show

  # Extract the request parameters

  type = params[ :id ]

  raise "Chart type #{type} is unknown" if ( type != ChartsHelper::CHART_TYPE_PIE.to_s )

  leaf          = ( params[ :leaf          ] || 'chart' )
  width         = ( params[ :width         ] || '128'   ).to_i
  duration      = ( params[ :duration      ] || '1_0'   ).sub( '_', '.' ).to_f
  committed     = ( params[ :committed     ] || '0_2'   ).sub( '_', '.' ).to_f
  not_committed = ( params[ :not_committed ] || '0_5'   ).sub( '_', '.' ).to_f
  remaining     = duration - committed - not_committed

  # Stop silly widths from loading the server unnecessarily.

  width = 40  if ( width < 40  );
  width = 640 if ( width > 640 );

  g                  = Gruff::Mini::Pie.new( "#{ width }x#{ width * 0.75 }" )
  g.title            = 'Chart'
  g.font             = "#{ Rails.root }/#{ GRAPH_FONT }"
  g.hide_legend      = true
  g.hide_title       = true
  g.marker_font_size = 70

  # Is this a normal or overrun graph?

  if ( remaining >= 0 or duration == 0 )

    g.theme = {
      :colors            => %w( #cc7777 #ffaa77 #99ff99 ),
      :background_colors => %w( white   white           ),
      :marker_color      => 'black'
    }

    # Can't have a pie chart where every entry has zero size;
    # set the remaining time to 100 (as in, 100%) in that case.

    remaining = 0   if ( remaining  < 0 ) # Zero duration task
    remaining = 100 if ( remaining == 0 and committed == 0 and not_committed == 0 )

    g.data( 'Committed',     committed     )
    g.data( 'Not committed', not_committed )
    g.data( 'Remaining',     remaining     )

  else

    g.theme = {
      :colors            => %w( #ffaa77 #880000 #000000 ),
      :background_colors => %w( white   white           ),
      :marker_color      => 'black'
    }

    g.data( 'Duration', duration   )
    g.data( 'Overrun',  -remaining )
    g.data( '-', 0 )

  end

  # Start the chart at 12:00

  g.zero_degree = -90

  # Send out the result

  send_data(
    g.to_blob,
    :disposition => 'inline',
    :type        => 'image/png',
    :filename    => "#{ leaf }.png"
  )
end