Class: Prawn::Canvas

Inherits:
Object
  • Object
show all
Includes:
Chunkable
Defined in:
lib/prawn/canvas.rb

Constant Summary collapse

KAPPA = 
4.0 * ((Math.sqrt(2) - 1.0) / 3.0)

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Chunkable

#chunk, #find_chunks, included, #to_pdf

Constructor Details

#initialize ⇒ Canvas

Returns a new instance of Canvas.



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# File 'lib/prawn/canvas.rb', line 5

def initialize
  @chunks = []
end

Instance Attribute Details

#chunks ⇒ Object

Returns the value of attribute chunks.



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# File 'lib/prawn/canvas.rb', line 9

def chunks
  @chunks
end

Instance Method Details

#circle!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 81

def circle!(params)
  chunk(:circle, params) do
    ellipse!(:point    => params[:point],
             :x_radius => params[:radius],
             :y_radius => params[:radius]) 
                
  end
end

#curve!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 36

def curve!(params)
  chunk(:curve, params) do |c|
    [ move_to!(:point => params[:point1]),
      curve_to!(:point  => params[:point2],
                :bound1 => params[:bound1],
                :bound2 => params[:bound2]) ]

  end
end

#curve_to!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 26

def curve_to!(params)
  unless params[:bound1] && params[:bound2]
    raise Prawn::Errors::InvalidGraphicsPath
  end

  chunk(:curve_to, params) do |c|
    "%.3f %.3f %.3f %.3f %.3f %.3f c" % (c[:bound1] + c[:bound2] + c[:point])
  end
end

#ellipse!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 48

def ellipse!(params)
  chunk(:ellipse, params) do |c|
    x, y = c[:point]
    r1   = c[:x_radius]
    r2   = c[:y_radius]

    l1 = r1 * KAPPA
    l2 = r2 * KAPPA

    start          =  move_to!(:point => [x + r1, y])

    to_upper_right = curve_to!(:point  => [x,  y + r2],
                               :bound1 => [x + r1, y + l1], 
                               :bound2 => [x + l2, y + r2])
    to_upper_left = curve_to!(:point => [x - r1, y],
                              :bound1 => [x - l2, y + r2],
                              :bound2 => [x - r1, y + l1])
    
    to_lower_left = curve_to!(:point => [x, y - r2],
                              :bound1 => [x - r1, y - l1], 
                              :bound2 => [x - l2, y - r2])

    to_lower_right = curve_to!(:point  => [x + r1, y],
                               :bound1 => [x + l2, y - r2], 
                               :bound2 => [x + r1, y - l1])

    back_to_start = move_to!(:point => [x,y])

    [start, to_upper_right, to_upper_left,
            to_lower_left,  to_lower_right, back_to_start]
  end
end

#fill! ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 101

def fill!
  chunk(:fill) { "F" }
end

#fill_and_stroke! ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 105

def fill_and_stroke!
  chunk(:fill_and_stroke) { "b" }
end

#line!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 90

def line!(params)
  chunk(:line, params) do |c|
    [ move_to!(:point => c.params[:point1]), 
      line_to!(:point => c.params[:point2]) ]
  end
end

#line_to!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 20

def line_to!(params)
  chunk(:line_to, params) do |c|
    "%.3f %.3f l" % c[:point]
  end
end

#move_to!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 14

def move_to!(params)
  chunk(:move_to, params) do |c|
    "%.3f %.3f m" % c[:point]
  end
end

#rectangle!(params) ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 109

def rectangle!(params)
  chunk(:rectangle, params) do |c|
    x,y = params[:point]
    y  -= params[:height]

    "%.3f %.3f %.3f %.3f re" % [ x, y, params[:width], params[:height] ]
  end
end

#stroke! ⇒ Object 



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# File 'lib/prawn/canvas.rb', line 97

def stroke!
  chunk(:stroke) { "S" }
end