class Scruffy::Layers::Base
Scruffy::Layers::Base¶ ↑
- Author
-
Brasten Sager
- Extended By
-
A.J. Ostman
- Created
-
August 5th, 2006
- Last Modified
-
August 27, 2006
Scruffy::Layers::Base contains the basic functionality needed by the various types of graphs. The Base class is responsible holding layer information such as the title and data points.
When the graph is rendered, the graph renderer calls #render. #render sets up some standard information, and calculates the x,y coordinates of each data point. The draw() method, which should have been overridden by the current instance, is then called. The actual rendering of the graph takes place there.
Create New Graph Types¶ ↑
Assuming the information generated by Scruffy::Layers::Base is sufficient, you can create a new graph type simply by overriding the draw() method. See #draw for arguments.
Attributes
The following attributes are set during the layer's render process, and act more as a record of what just happened for later processes. height, width, #min_value, #max_value, color, opacity, complexity
The following attributes are user-definable at any time. title, points, #relevant_data, #preferred_color, options
The following attributes are set during the layer's render process, and act more as a record of what just happened for later processes. height, width, #min_value, #max_value, color, opacity, complexity
Public Class Methods
Returns a new Base object.
Any options other that those specified below are stored in the @options variable for possible later use. This would be a good place to store options needed for a custom graph.
Options:
- title
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Name/title of data group
- points
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Array of data points
- #preferred_color
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Color used to render this graph, overrides theme color.
- #relevant_data
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Rarely used - indicates the data on this graph should not included in any graph data aggregations, such as averaging data points.
# File lib/scruffy/layers/base.rb, line 52 def initialize(options = {}) @title = options.delete(:title) || '' @preferred_color = options.delete(:preferred_color) @relevant_data = options.delete(:relevant_data) || true @points = options.delete(:points) || [] @points.extend Scruffy::Helpers::PointContainer unless @points.kind_of? Scruffy::Helpers::PointContainer @options = options end
Public Instance Methods
The lowest data point on this layer, or nil if #relevant_data == false
# File lib/scruffy/layers/base.rb, line 112 def bottom_value @relevant_data ? points.minimum_value : nil end
The method called by #draw to render the graph.
- svg
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a Builder object to use for creating SVG code.
- coords
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An array of coordinates relating to the graph's data points. ie: [[100, 120], [200, 140], [300, 40]]
- options
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Optional arguments.
# File lib/scruffy/layers/base.rb, line 79 def draw(svg, coords, options={}) raise RenderError, "You must override the Base#draw method." end
Returns a hash with information to be used by the legend.
Alternatively, returns nil if you don't want this layer to be in the legend, or an array of hashes if this layer should have multiple legend entries (stacked?)
By default, legend_data returns nil automatically if #relevant_data is set to false or the @color attribute is nil. @color is set when the layer is rendered, so legends must be rendered AFTER layers.
# File lib/scruffy/layers/base.rb, line 91 def legend_data if relevant_data? && @color {:title => title, :color => @color, :priority => :normal} else nil end end
Returns the value of #relevant_data
# File lib/scruffy/layers/base.rb, line 102 def relevant_data? @relevant_data end
Builds SVG code for this graph using the provided Builder object. This method actually generates data needed by this graph, then passes the rendering responsibilities to #draw.
- svg
-
a Builder object used to create SVG code.
# File lib/scruffy/layers/base.rb, line 67 def render(svg, options = {}) setup_variables(options) coords = generate_coordinates(options) draw(svg, coords, options) end
The sum of all values
# File lib/scruffy/layers/base.rb, line 117 def sum_values points.sum end
The highest data point on this layer, or nil if #relevant_data == false
# File lib/scruffy/layers/base.rb, line 107 def top_value @relevant_data ? points.maximum_value : nil end
Protected Instance Methods
Optimistic generation of coordinates for layer to use. These coordinates are just a best guess, and can be overridden or thrown away (for example, this is overridden in pie charting and bar charts).
# File lib/scruffy/layers/base.rb, line 135 def generate_coordinates(options = {}) options[:point_distance] = width / (points.size - 1).to_f points.inject_with_index([]) do |memo, point, idx| x_coord = options[:point_distance] * idx if point relative_percent = ((point == min_value) ? 0 : ((point - min_value) / (max_value - min_value).to_f)) y_coord = (height - (height * relative_percent)) memo << [x_coord, y_coord] end memo end end
Converts a percentage into a pixel value, relative to the height.
Example:
relative(5) # On a 100px high layer, this returns 5. 200px high layer, this returns 10, etc.
# File lib/scruffy/layers/base.rb, line 156 def relative(pct) # Default to Relative Height relative_height(pct) end
# File lib/scruffy/layers/base.rb, line 167 def relative_height(pct) if pct # Added to handle nils @height * (pct / 100.to_f) end end
# File lib/scruffy/layers/base.rb, line 161 def relative_width(pct) if pct # Added to handle nils @width * (pct / 100.to_f) end end
Sets up several variables that almost every graph layer will need to render itself.
# File lib/scruffy/layers/base.rb, line 124 def setup_variables(options = {}) @color = (preferred_color || options.delete(:color)) @width, @height = options.delete(:size) @min_value, @max_value = options[:min_value], options[:max_value] @opacity = options[:opacity] || 1.0 @complexity = options[:complexity] end