Class: Prawn::Images::Image

Inherits:
Object
  • Object
show all
Defined in:
lib/prawn/images/image.rb

Direct Known Subclasses

JPG, PNG

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.detect_image_format(content) ⇒ Object 



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# File 'lib/prawn/images/image.rb', line 47

def self.detect_image_format(content)
  top = content[0,128]                       

  # Unpack before comparing for JPG header, so as to avoid having to worry
  # about the source string encoding. We just want a byte-by-byte compare.
  if top[0, 3].unpack("C*") == [255, 216, 255]
    return :jpg
  elsif top[0, 8].unpack("C*") == [137, 80, 78, 71, 13, 10, 26, 10]
    return :png
  else
    raise Errors::UnsupportedImageType, "image file is an unrecognised format"
  end
end

Instance Method Details

#calc_image_dimensions(options) ⇒ Object 



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# File 'lib/prawn/images/image.rb', line 14

def calc_image_dimensions(options)
  w = options[:width] || width
  h = options[:height] || height

  if options[:width] && !options[:height]
    wp = w / width.to_f 
    w = width * wp
    h = height * wp
  elsif options[:height] && !options[:width]         
    hp = h / height.to_f
    w = width * hp
    h = height * hp   
  elsif options[:scale] 
    w = width * options[:scale]
    h = height * options[:scale]
  elsif options[:fit] 
    bw, bh = options[:fit]
    bp = bw / bh.to_f
    ip = width / height.to_f
    if ip > bp
      w = bw
      h = bw / ip
    else
      h = bh
      w = bh * ip
    end
  end
  self.scaled_width = w
  self.scaled_height = h

  [w,h]
end