Class: CSSquirt::ImageFile

Inherits:
Object
  • Object
show all
Defined in:
lib/cssquirt/image_file.rb

Constant Summary collapse

MAX_FILE_SIZE = 
32768
VALID_FILE_MIMETYPES = 
['image/png', 'image/jpeg', 'image/gif', 'image/svg+xml']

Instance Method Summary collapse

Constructor Details

#initialize(file_path) ⇒ ImageFile

Public: Intialize a new ImageFile object.

file_path - A String representing the relative path to an image file.

Raises IOError if the file cannot be found. Raises TypeError if the file is not a valid image file. Raises RangeError if the file is larger than the maximum size that can be

encoded as a Data URI (default: 32 kilobytes).

Raises:

  • (IOError) 


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# File 'lib/cssquirt/image_file.rb', line 16

def initialize(file_path)
  @file_path = file_path
  raise IOError, "No file found at #{file_path}!" unless File.exist? file_path

  unless self.valid_image_format?
    raise TypeError, "File #{file_path} reports type #{self.filetype} which is not a supported image format."
  end

  file_size = File.size(@file_path)
  if file_size > MAX_FILE_SIZE
    raise RangeError, "File #{file_path} is too big - #{file_size} greater than #{MAX_FILE_SIZE}."
  end
end

Instance Method Details

#as_css_background ⇒ Object

Public: Formats a CSS background image rule for the file.

Returns the CSS background rule as a String.



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# File 'lib/cssquirt/image_file.rb', line 66

def as_css_background()
  "background: url(#{self.encode}) no-repeat;"
end

#as_css_background_with_class(klass = nil) ⇒ Object

Public: Formats a CSS background image rule for the file, and wraps

it in a class definition.

klass - The name of the class to use for the CSS rule. Optional. If

ommitted, the default will the basename of the file path.

Returns the class wrapped CSS background rule as a String.



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# File 'lib/cssquirt/image_file.rb', line 58

def as_css_background_with_class(klass=nil)
  klass=File.basename(@file_path).tr('.','_') unless klass
  ".#{klass} {\n  #{self.as_css_background}\n}"
end

#as_img_tag ⇒ Object

Public: Formats a data-uri based HTML IMG tag for the file.

Returns the entire IMG tag as a String.



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# File 'lib/cssquirt/image_file.rb', line 47

def as_img_tag()
  "<img src='#{self.encode}' />"
end

#encode ⇒ Object

Public: Encodes file into a CSS string representation.

Returns the Base64 encoded String with filetype information embedded.



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# File 'lib/cssquirt/image_file.rb', line 73

def encode()
  "data:#{self.filetype};base64," + self.raw_encode
end

#filetype ⇒ Object

Public: Returns the MIME type for the file.

Examples

ImageFile.new('example.png')
# => 'image/png'
ImageFile.new('example.svg')
# => 'image/svg+xml'

Returns a String representation of the MIME type.



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# File 'lib/cssquirt/image_file.rb', line 40

def filetype
  `file --mime-type -b #{@file_path}`.chomp
end

#raw_encode ⇒ Object

Public: file into its raw Base64 string representation.

Returns the Base64 encoded String.



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# File 'lib/cssquirt/image_file.rb', line 80

def raw_encode()
  return Base64.encode64(File.read @file_path).delete("\n") if RUBY_VERSION < "1.9.0"
  Base64.strict_encode64(File.read @file_path)
end