Prawn::Graphics::Transformation

Public Instance Methods

rotate(angle, options={}, &block) click to toggle source

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

Options

:origin

[number, number]. The point around which to rotate. A block must be provided if using the :origin

raises Prawn::Errors::BlockRequired if an :origin option is provided, but no block is given

Example without a block:

  
  save_graphics_state
  rotate 30
  text "rotated text"
  restore_graphics_state

Example with a block: 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

    # File lib/prawn/graphics/transformation.rb, line 42
42:       def rotate(angle, options={}, &block)
43:         Prawn.verify_options(:origin, options)
44:         rad = degree_to_rad(angle)
45:         cos = Math.cos(rad)
46:         sin = Math.sin(rad)
47:         if options[:origin].nil?
48:           transformation_matrix(cos, sin, -sin, cos, 0, 0, &block)
49:         else
50:           raise Prawn::Errors::BlockRequired unless block_given?
51:           x = options[:origin][0] + bounds.absolute_left
52:           y = options[:origin][1] + bounds.absolute_bottom
53:           x_prime = x * cos - y * sin
54:           y_prime = x * sin + y * cos
55:           translate(x - x_prime, y - y_prime) do
56:             transformation_matrix(cos, sin, -sin, cos, 0, 0, &block)
57:           end
58:         end
59:       end

scale(factor, options={}, &block) click to toggle source

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

Options

:origin

[number, number]. The point from which to scale. A block must be provided if using the :origin

raises Prawn::Errors::BlockRequired if an :origin option is provided, but no block is given

Example without a block:

  
  save_graphics_state
  scale 1.5
  text "scaled text"
  restore_graphics_state

Example with a block: 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

     # File lib/prawn/graphics/transformation.rb, line 114
114:       def scale(factor, options={}, &block)
115:         Prawn.verify_options(:origin, options)
116:         if options[:origin].nil?
117:           transformation_matrix(factor, 0, 0, factor, 0, 0, &block)
118:         else
119:           raise Prawn::Errors::BlockRequired unless block_given?
120:           x = options[:origin][0] + bounds.absolute_left
121:           y = options[:origin][1] + bounds.absolute_bottom
122:           x_prime = factor * x
123:           y_prime = factor * y
124:           translate(x - x_prime, y - y_prime) do
125:             transformation_matrix(factor, 0, 0, factor, 0, 0, &block)
126:           end
127:         end
128:       end

transformation_matrix(a, b, c, d, e, f) click to toggle source

Transform the user space (see notes for rotate regarding graphics state) Generally, one would use the rotate, scale, translate, and skew convenience methods instead of calling transformation_matrix directly

     # File lib/prawn/graphics/transformation.rb, line 144
144:       def transformation_matrix(a, b, c, d, e, f)
145:         values = [a, b, c, d, e, f].map { |x| "%.5f" % x }.join(" ")
146:         save_graphics_state if block_given?
147:         add_content "#{values} cm"
148:         if block_given?
149:           yield
150:           restore_graphics_state
151:         end
152:       end

translate(x, y, &block) click to toggle source

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

Example without a block: move the text up and over 10

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

Example with a block: 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

    # File lib/prawn/graphics/transformation.rb, line 82
82:       def translate(x, y, &block)
83:         transformation_matrix(1, 0, 0, 1, x, y, &block)
84:       end

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Prawn::Graphics::Transformation

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