Class: Scruffy::Graph

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
Helpers::LayerContainer
Defined in:
lib/scruffy/graph.rb

Overview

Scruffy Graphs

Author

Brasten Sager

Date

August 5th, 2006

Graphs vs. Layers (Graph Types)

Scruffy::Graph is the primary class you will use to generate your graphs. A Graph does not define a graph type nor does it directly hold any data. Instead, a Graph object can be thought of as a canvas on which other graphs are draw. (The actual graphs themselves are subclasses of Scruffy::Layers::Base) Despite the technical distinction, we will refer to Scruffy::Graph objects as ‘graphs’ and Scruffy::Layers as ‘layers’ or ‘graph types.’

Creating a Graph

You can begin building a graph by instantiating a Graph object and optionally passing a hash of properties.

graph = Scruffy::Graph.new

OR

graph = Scruffy::Graph.new(:title => "Monthly Profits", :theme => Scruffy::Themes::RubyBlog.new)

Once you have a Graph object, you can set any Graph-level properties (title, theme, etc), or begin adding graph layers. You can add a graph layer to a graph by using the Graph#add or Graph#<< methods. The two methods are identical and used to accommodate syntax preferences.

graph.add(:line, 'John', [100, -20, 30, 60])
graph.add(:line, 'Sara', [120, 50, -80, 20])

OR

graph << Scruffy::Layers::Line.new(:title => 'John', :points => [100, -20, 30, 60])
graph << Scruffy::Layers::Line.new(:title => 'Sara', :points => [120, 50, -80, 20])

Now that we’ve created our graph and added a layer to it, we’re ready to render! You can render the graph directly to SVG or any other image format (supported by RMagick) with the Graph#render method:

graph.render    # Renders a 600x400 SVG graph

OR

graph.render(:width => 1200)

# For image formats other than SVG:
graph.render(:width => 1200, :as => 'PNG')

# To render directly to a file:
graph.render(:width => 5000, :to => '<filename>')

graph.render(:width => 700, :as => 'PNG', :to => '<filename>')

And that’s your basic Scruffy graph! Please check the documentation for the various methods and classes you’ll be using, as there are a bunch of options not demonstrated here.

A couple final things worth noting:

  • You can call Graph#render as often as you wish with different rendering options. In fact, you can modify the graph any way you wish between renders.

  • There are no restrictions to the combination of graph layers you can add. It is perfectly valid to do something like:

    graph.add(:line, [100, 200, 300])
graph.add(:bar, [200, 150, 150])

    Of course, while you may be able to combine some things such as pie charts and line graphs, that doesn’t necessarily mean they will make any logical sense together. We leave those decisions up to you. :)

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Helpers::LayerContainer

#<<, #bottom_value, #layers, #layers=, #top_value

Constructor Details

#initialize(*args) ⇒ Graph

Returns a new Graph. You can optionally pass in a default graph type and an options hash.

Graph.new           # New graph
Graph.new(:line)    # New graph with default graph type of Line
Graph.new({...})    # New graph with options.

Options:

title

Graph’s title

theme

A theme object to use when rendering graph

layers

An array of Layers for this graph to use

default_type

A symbol indicating the default type of Layer for this graph

value_formatter

Sets a formatter used to modify marker values prior to rendering

point_markers

Sets the x-axis marker values

rasterizer

Sets the rasterizer to use when rendering to an image format. Defaults to RMagick.

Raises:

  • (ArgumentError) 


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# File 'lib/scruffy/graph.rb', line 105

def initialize(*args)
  self.default_type   = args.shift if args.first.is_a?(Symbol)
  options             = args.shift.dup if args.first.is_a?(Hash)
  raise ArgumentError, "The arguments provided are not supported." if args.size > 0

  options ||= {}
  self.theme = Scruffy::Themes::Standard.new
  self.renderer = Scruffy::Renderers::Standard.new
  self.rasterizer = Scruffy::Rasterizers::RMagickRasterizer.new
  self.value_formatter = Scruffy::Formatters::Number.new

  %w(title theme layers default_type value_formatter point_markers rasterizer).each do |arg|
    self.send("#{arg}=".to_sym, options.delete(arg.to_sym)) unless options[arg.to_sym].nil?
  end
  
  raise ArgumentError, "Some options provided are not supported: #{options.keys.join(' ')}." if options.size > 0
end

Instance Attribute Details

#renderer ⇒ Object Also known as: layout

Writer defined below



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# File 'lib/scruffy/graph.rb', line 88

def renderer
  @renderer
end

Instance Method Details

#component(id) ⇒ Object 



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# File 'lib/scruffy/graph.rb', line 176

def component(id)
  renderer.component(id)
end

#remove(id) ⇒ Object 



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# File 'lib/scruffy/graph.rb', line 180

def remove(id)
  renderer.remove(id)
end

#render(options = {}) ⇒ Object

Renders the graph in it’s current state to an SVG object.

Options:

size

An array indicating the size you wish to render the graph. ( [x, y] )

width

The width of the rendered graph. A height is calculated at 3/4th of the width.

theme

Theme used to render graph for this render only.

min_value

Overrides the calculated minimum value used for the graph.

max_value

Overrides the calculated maximum value used for the graph.

renderer

Provide a Renderer object to use instead of the default.

For other image formats:

as

File format to render to (‘PNG’, ‘JPG’, etc)

to

Name of file to save graph to, if desired. If not provided, image is returned as blob/string.



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# File 'lib/scruffy/graph.rb', line 136

def render(options = {})
  options[:theme]               ||= theme
  options[:value_formatter]     ||= value_formatter
  options[:point_markers]       ||= point_markers
  options[:size]                ||= (options[:width] ? [options[:width], (options.delete(:width) * 0.6).to_i] : [600, 360])
  options[:title]               ||= title
  options[:layers]              ||= layers
  options[:min_value]           ||= bottom_value(:padded)
  options[:max_value]           ||= top_value
  options[:graph]               ||= self
  

  # Removed for now.
  # Added for making smaller fonts more legible, but may not be needed after all.
  #
  # if options[:as] && (options[:size][0] <= 300 || options[:size][1] <= 200)
  #   options[:actual_size] = options[:size]
  #   options[:size] = [800, (800.to_f * (options[:actual_size][1].to_f / options[:actual_size][0].to_f))]
  # end
  
  svg = ( options[:renderer].nil? ? self.renderer.render( options ) : options[:renderer].render( options ) )
  
  # SVG to file.
  if options[:to] && options[:as].nil?
    File.open(options[:to], 'w') { |file|
      file.write(svg)
    }
  end
  
  options[:as] ? rasterizer.rasterize(svg, options) : svg
end