Class: Bio::Graphics::Ruler

Inherits:
Object
  • Object
show all
Defined in:
lib/bio/graphics/ruler.rb

Overview

The Bio::Graphics::Ruler class describes the ruler to be drawn on the graph. This is created automatically when creating the picture by using Bio::Graphics::Panel.to_svg. See BioExt::Graphics documentation for explanation of interplay between different classes. – TODO: the ruler might be implemented as a special case of a track, so it would inherit from it (class Ruler < Bio::Graphics::Track). But I haven't really thought this through yet. ++

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(panel, colour = [0,0,0]) ⇒ Ruler

Creates a new Bio::Graphics::Ruler object.


Arguments:

  • panel (required)

    Bio::Graphics::Panel object that this ruler

    belongs to

  • colour

    colour of the ruler. Default = 'black'

Returns

Bio::Graphics::Ruler object


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# File 'lib/bio/graphics/ruler.rb', line 27

def initialize(panel, colour = [0,0,0])
  @panel = panel
  @name = 'ruler'
  @colour = colour
  
  # Number of pixels between each tick, used to calculate tick spacing
  @min_pixels_per_tick = 5
  # The base height of minor ticks in pixels
  @tick_height = 5
  # The height of the text in pixels
  @tick_text_height = 10

  @minor_tick_distance = @min_pixels_per_tick ** self.scaling_factor
  @major_tick_distance = @minor_tick_distance * 10       
end

Instance Attribute Details

#colourObject

Returns the value of attribute colour


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# File 'lib/bio/graphics/ruler.rb', line 42

def colour
  @colour
end

#heightObject

Returns the value of attribute height


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# File 'lib/bio/graphics/ruler.rb', line 42

def height
  @height
end

#major_tick_distanceObject

Returns the value of attribute major_tick_distance


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# File 'lib/bio/graphics/ruler.rb', line 42

def major_tick_distance
  @major_tick_distance
end

#min_pixels_per_tickObject

Returns the value of attribute min_pixels_per_tick


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# File 'lib/bio/graphics/ruler.rb', line 42

def min_pixels_per_tick
  @min_pixels_per_tick
end

#minor_tick_distanceObject

Returns the value of attribute minor_tick_distance


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# File 'lib/bio/graphics/ruler.rb', line 42

def minor_tick_distance
  @minor_tick_distance
end

#nameObject

Returns the value of attribute name


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# File 'lib/bio/graphics/ruler.rb', line 42

def name
  @name
end

#panelObject

Returns the value of attribute panel


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# File 'lib/bio/graphics/ruler.rb', line 42

def panel
  @panel
end

#tick_heightObject

Returns the value of attribute tick_height


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# File 'lib/bio/graphics/ruler.rb', line 42

def tick_height
  @tick_height
end

#tick_text_heightObject

Returns the value of attribute tick_text_height


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# File 'lib/bio/graphics/ruler.rb', line 42

def tick_text_height
  @tick_text_height
end

Instance Method Details

#draw(panel_drawing) ⇒ Object


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# File 'lib/bio/graphics/ruler.rb', line 64

def draw(panel_drawing)
  ruler_drawing = Cairo::Context.new(panel_drawing)

  # Draw line
  ruler_drawing.move_to(0,10)
  ruler_drawing.line_to(panel.width, 10)
  ruler_drawing.stroke

  # Draw ticks
  #  * And start drawing the rest.
  first_tick_position.step(@panel.display_stop, @minor_tick_distance) do |tick|
    tick_pixel_position = (tick - panel.display_start) / @panel.rescale_factor
    ruler_drawing.move_to(tick_pixel_position.floor, @min_pixels_per_tick)
    if tick.modulo(@major_tick_distance) == 0
      ruler_drawing.rel_line_to(0, 3*@tick_height)
      
      # Draw tick number
      ruler_drawing.select_font_face(*Bio::Graphics::FONT)
      ruler_drawing.set_font_size(@tick_text_height)
      ruler_drawing.move_to(tick_pixel_position.floor, 4*@tick_height + @tick_text_height)
      ruler_drawing.show_text(tick.to_i.to_s)
    else
      ruler_drawing.rel_line_to(0, @tick_height)
      
    end
    ruler_drawing.stroke
  end

  @height = 5*@tick_height + @tick_text_height          
end

#first_tick_position(start = @panel.display_start, minor_tick = @minor_tick_distance) ⇒ Object


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# File 'lib/bio/graphics/ruler.rb', line 52

def first_tick_position(start = @panel.display_start,
                        minor_tick = @minor_tick_distance)
  #  * Find position of first tick.
  #    Most of the time, we don't want the first tick on the very first
  #    basepair of the view. Suppose that would be position 333 in the
  #    sequence. Then the numbers under the major tickmarks would be:
  #    343, 353, 363, 373 and so on. Instead, we want 350, 360, 370, 380.
  #    So we want to find the position of the first tick.
  modulo_from_tick = (start % minor_tick)
  start + (modulo_from_tick > 0 ? (minor_tick - modulo_from_tick + 1) : 0)
end

#scaling_factor(min_pixels_per_tick = @min_pixels_per_tick, rescale_factor = @panel.rescale_factor) ⇒ Object


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# File 'lib/bio/graphics/ruler.rb', line 46

def scaling_factor(min_pixels_per_tick = @min_pixels_per_tick,
                        rescale_factor = @panel.rescale_factor)
  (Math.log(min_pixels_per_tick * rescale_factor) /
   Math.log(min_pixels_per_tick)).ceil 
end