Class Scruffy::Graph
In: lib/scruffy/graph.rb
Parent: Object

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. :)

Methods

component   new   remove   render   renderer=  

Included Modules

Scruffy::Helpers::LayerContainer

External Aliases

renderer -> layout

Attributes

default_type  [RW] 
point_markers  [RW] 
rasterizer  [RW] 
renderer  [R] 
theme  [RW] 
title  [RW] 
value_formatter  [RW] 

Public Class methods

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.

Public Instance methods

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.

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.

[Validate]