Module: Prawn::Graphics::Transformation

Included in:
Prawn::Graphics
Defined in:
lib/prawn/graphics/transformation.rb

Overview

Implements user-space coordinate transformation.

Stable API collapse

Instance Method Details

#rotate(angle, options = {}) { ... } ⇒ void

This method returns an undefined value.

Rotate the user space. If a block is not provided, then you must save and restore the graphics state yourself.

Examples:

save_graphics_state
rotate 30
text "rotated text"
restore_graphics_state

Rotating a rectangle around its upper-left corner

x = 300
y = 300
width = 150
height = 200
angle = 30
pdf.rotate(angle, :origin => [x, y]) do
  pdf.stroke_rectangle([x, y], width, height)
end

Parameters:

  • angle (Number) —

    Angle in degrees.

  • options (Hash{Symbol => any}) (defaults to: {})

Options Hash (options):

  • :origin (Array(Number, Number)) —

    Rotation origin point. A block must be provided if specified.

Yields:

Raises:

Source Code
lib/prawn/graphics/transformation.rb, line 36
36
def rotate(angle, options = {}, &block)

37
  Prawn.verify_options(:origin, options)

38
  rad = degree_to_rad(angle)

39
  cos = Math.cos(rad)

40
  sin = Math.sin(rad)

41
  if options[:origin].nil?

42
    transformation_matrix(cos, sin, -sin, cos, 0, 0, &block)

43
  else

44
    raise Prawn::Errors::BlockRequired unless block

45
46
    x = options[:origin][0] + bounds.absolute_left

47
    y = options[:origin][1] + bounds.absolute_bottom

48
    x_prime = (x * cos) - (y * sin)

49
    y_prime = (x * sin) + (y * cos)

50
    translate(x - x_prime, y - y_prime) do

51
      transformation_matrix(cos, sin, -sin, cos, 0, 0, &block)

52
    end

53
  end

54
end







    
      

  

  
    #scale(factor, options = {}) { ... } ⇒ void 
  

  

  


  

    
This method returns an undefined value.
Scale the user space. If a block is not provided, then you must save
and restore the graphics state yourself.



  





  
  

    
Examples:

    
      
      
save_graphics_state
scale 1.5
text "scaled text"
restore_graphics_state


    
      
        
Scale a rectangle from its upper-left corner



      
      
x = 300
y = 300
width = 150
height = 200
factor = 1.5
pdf.scale(angle, :origin => [x, y]) do
  pdf.stroke_rectangle([x, y], width, height)
end


    
  



Parameters:


    
  
    
  • 
      
        factor
      
      
        (Number)
      
      
      
        —
        
    Scale factor.
    

    
      
    
    • 
  
    
  • 
      
        options
      
      
        (Hash{Symbol => any})
      
      
        (defaults to: {})
      
      
    
    • 
  



  
    
    
    
    
    
Options Hash (options):

    
    
      
        
  • 
          :origin
          (Array(Number, Number))
          
            
          
          
            — 
    The point from which to
scale. A block must be provided if specified.
    

    
          
        
    • 
      
    

  


Yields:


    
  
    
  • 
      
      
        
      
      
      
    
    • 
  



Raises:







  Source Code
  
lib/prawn/graphics/transformation.rb, line 109

  
109
def scale(factor, options = {}, &block)

110
  Prawn.verify_options(:origin, options)

111
  if options[:origin].nil?

112
    transformation_matrix(factor, 0, 0, factor, 0, 0, &block)

113
  else

114
    raise Prawn::Errors::BlockRequired unless block

115
116
    x = options[:origin][0] + bounds.absolute_left

117
    y = options[:origin][1] + bounds.absolute_bottom

118
    x_prime = factor * x

119
    y_prime = factor * y

120
    translate(x - x_prime, y - y_prime) do

121
      transformation_matrix(factor, 0, 0, factor, 0, 0, &block)

122
    end

123
  end

124
end







    
      

  

  
    #transformation_matrix(*matrix) { ... } ⇒ void 
  

  

  


  

    
This method returns an undefined value.
Transform the user space (see notes for rotate regarding graphics state)
Generally, one would use the #rotate, #scale, and #translate
convenience methods instead of calling transformation_matrix directly



  





  

Parameters:


    
  
    
  • 
      
        matrix
      
      
        (Array(Number, Number, Number, Number, Number, Number))
      
      
      
        —
        
    Transformation matrix.
    


    The six elements correspond to the following elements of the
transformation matrix:
    


    a b 0
c d 0
e f 0

    

    
      
    
    • 
  




Yields:


    
  
    
  • 
      
      
        
      
      
      
    
    • 
  







  Source Code
  
lib/prawn/graphics/transformation.rb, line 154

  
154
def transformation_matrix(*matrix)

155
  if matrix.length != 6

156
    raise ArgumentError,

157
      'Transformation matrix must have exacty 6 elements'

158
  end

159
  save_graphics_state if block_given?

160
161
  add_to_transformation_stack(*matrix)

162
163
  values = PDF::Core.real_params(matrix)

164
  renderer.add_content("#{values} cm")

165
  if block_given?

166
    yield

167
    restore_graphics_state

168
  end

169
end







    
      

  

  
    #translate(x, y) { ... } ⇒ void 
  

  

  


  

    
This method returns an undefined value.
Translate the user space. If a block is not provided, then you must
save and restore the graphics state yourself.



  





  
  

    
Examples:

    
      
        
Move the text up and over 10



      
      
save_graphics_state
translate(10, 10)
text "scaled text"
restore_graphics_state


    
      
        
draw a rectangle with its upper-left corner at x + 10, y + 10



      
      
x = 300
y = 300
width = 150
height = 200
pdf.translate(10, 10) do
  pdf.stroke_rectangle([x, y], width, height)
end


    
  



Parameters:


    
  
    
  • 
      
        x
      
      
        (Number)
      
      
      
    
    • 
  
    
  • 
      
        y
      
      
        (Number)
      
      
      
    
    • 
  




Yields:


    
  
    
  • 
      
      
        
      
      
      
    
    • 
  







  Source Code
  
lib/prawn/graphics/transformation.rb, line 78

  
78
def translate(x, y, &block)

79
  transformation_matrix(1, 0, 0, 1, x, y, &block)

80
end