class Paperclip::Thumbnail

Handles thumbnailing images that are uploaded.

Constants

ANIMATED_FORMATS

List of formats that we need to preserve animation

Attributes

animated[RW]
auto_orient[RW]
convert_options[RW]
current_geometry[RW]
format[RW]
source_file_options[RW]
target_geometry[RW]
whiny[RW]

Public Class Methods

new(file, options = {}, attachment = nil) click to toggle source

Creates a Thumbnail object set to work on the file given. It will attempt to transform the image into one defined by target_geometry which is a “WxH”-style string. format will be inferred from the file unless specified. Thumbnail creation will raise no errors unless whiny is true (which it is, by default. If convert_options is set, the options will be appended to the convert command upon image conversion

Options include:

+geometry+ - the desired width and height of the thumbnail (required)
+file_geometry_parser+ - an object with a method named +from_file+ that takes an image file and produces its geometry and a +transformation_to+. Defaults to Paperclip::Geometry
+string_geometry_parser+ - an object with a method named +parse+ that takes a string and produces an object with +width+, +height+, and +to_s+ accessors. Defaults to Paperclip::Geometry
+source_file_options+ - flags passed to the +convert+ command that influence how the source file is read
+convert_options+ - flags passed to the +convert+ command that influence how the image is processed
+whiny+ - whether to raise an error when processing fails. Defaults to true
+format+ - the desired filename extension
+animated+ - whether to merge all the layers in the image. Defaults to true
# File lib/paperclip/thumbnail.rb, line 28
def initialize(file, options = {}, attachment = nil)
  super

  geometry             = options[:geometry] # this is not an option
  @file                = file
  @crop                = geometry[-1,1] == '#'
  @target_geometry     = (options[:string_geometry_parser] || Geometry).parse(geometry)
  @current_geometry    = (options[:file_geometry_parser] || Geometry).from_file(@file)
  @source_file_options = options[:source_file_options]
  @convert_options     = options[:convert_options]
  @whiny               = options[:whiny].nil? ? true : options[:whiny]
  @format              = options[:format]
  @animated            = options[:animated].nil? ? true : options[:animated]
  @auto_orient         = options[:auto_orient].nil? ? true : options[:auto_orient]

  @source_file_options = @source_file_options.split(%r\s+/) if @source_file_options.respond_to?(:split)
  @convert_options     = @convert_options.split(%r\s+/)     if @convert_options.respond_to?(:split)

  @current_format      = File.extname(@file.path)
  @basename            = File.basename(@file.path, @current_format)
end

Public Instance Methods

convert_options?() click to toggle source

Returns true if the image is meant to make use of additional convert options.

# File lib/paperclip/thumbnail.rb, line 56
def convert_options?
  !@convert_options.nil? && !@convert_options.empty?
end
crop?() click to toggle source

Returns true if the target_geometry is meant to crop.

# File lib/paperclip/thumbnail.rb, line 51
def crop?
  @crop
end
make() click to toggle source

Performs the conversion of the file into a thumbnail. Returns the Tempfile that contains the new image.

# File lib/paperclip/thumbnail.rb, line 62
def make
  src = @file
  dst = Tempfile.new([@basename, @format ? ".#{@format}" : ''])
  dst.binmode

  begin
    parameters = []
    parameters << source_file_options
    parameters << ":source"
    parameters << transformation_command
    parameters << convert_options
    parameters << ":dest"

    parameters = parameters.flatten.compact.join(" ").strip.squeeze(" ")

    success = convert(parameters, :source => "#{File.expand_path(src.path)}#{'[0]' unless animated?}", :dest => File.expand_path(dst.path))
  rescue Cocaine::ExitStatusError => e
    raise Paperclip::Error, "There was an error processing the thumbnail for #{@basename}" if @whiny
  rescue Cocaine::CommandNotFoundError => e
    raise Paperclip::Errors::CommandNotFoundError.new("Could not run the `convert` command. Please install ImageMagick.")
  end

  dst
end
transformation_command() click to toggle source

Returns the command ImageMagick’s convert needs to transform the image into the thumbnail.

# File lib/paperclip/thumbnail.rb, line 89
def transformation_command
  scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
  trans = []
  trans << "-coalesce" if animated?
  trans << "-auto-orient" if auto_orient
  trans << "-resize" << %Q["#{scale}"] unless scale.nil? || scale.empty?
  trans << "-crop" << %Q["#{crop}"] << "+repage" if crop
  trans
end

Protected Instance Methods

animated?() click to toggle source

Return true if the format is animated

# File lib/paperclip/thumbnail.rb, line 102
def animated?
  @animated && (ANIMATED_FORMATS.include?(@format.to_s) || @format.blank?)  && identified_as_animated?
end
identified_as_animated?() click to toggle source

Return true if ImageMagick’s identify returns an animated format

# File lib/paperclip/thumbnail.rb, line 107
def identified_as_animated?
  ANIMATED_FORMATS.include? identify("-format %m :file", :file => "#{@file.path}[0]").to_s.downcase.strip
rescue Cocaine::ExitStatusError => e
  raise Paperclip::Error, "There was an error running `identify` for #{@basename}" if @whiny
rescue Cocaine::CommandNotFoundError => e
  raise Paperclip::Errors::CommandNotFoundError.new("Could not run the `identify` command. Please install ImageMagick.")
end