class Paperclip::Thumbnail
Handles thumbnailing images that are uploaded.
Constants
- ANIMATED_FORMATS
List of formats that we need to preserve animation
Attributes
Public Class Methods
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].to_s @crop = geometry[-1,1] == '#' @target_geometry = options.fetch(:string_geometry_parser, Geometry).parse(geometry) @current_geometry = options.fetch(:file_geometry_parser, Geometry).from_file(@file) @source_file_options = options[:source_file_options] @convert_options = options[:convert_options] @whiny = options.fetch(:whiny, true) @format = options[:format] @animated = options.fetch(:animated, true) @auto_orient = options.fetch(:auto_orient, true) if @auto_orient && @current_geometry.respond_to?(:auto_orient) @current_geometry.auto_orient end @source_file_options = @source_file_options.split(/\s+/) if @source_file_options.respond_to?(:split) @convert_options = @convert_options.split(/\s+/) if @convert_options.respond_to?(:split) @current_format = File.extname(@file.path) @basename = File.basename(@file.path, @current_format) end
Public Instance Methods
Returns true if the image is meant to make use of additional convert options.
# File lib/paperclip/thumbnail.rb, line 58 def convert_options? !@convert_options.nil? && !@convert_options.empty? end
Returns true if the target_geometry
is meant to crop.
# File lib/paperclip/thumbnail.rb, line 53 def crop? @crop end
Performs the conversion of the file
into a thumbnail. Returns
the Tempfile that contains the new image.
# File lib/paperclip/thumbnail.rb, line 64 def make src = @file filename = [@basename, @format ? ".#{@format}" : ""].join dst = TempfileFactory.new.generate(filename) 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
Returns the command ImageMagick's convert
needs to
transform the image into the thumbnail.
# File lib/paperclip/thumbnail.rb, line 91 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 << '-layers "optimize"' if animated? trans end
Protected Instance Methods
Return true if the format is animated
# File lib/paperclip/thumbnail.rb, line 105 def animated? @animated && (ANIMATED_FORMATS.include?(@format.to_s) || @format.blank?) && identified_as_animated? end
Return true if ImageMagick's identify
returns an animated
format
# File lib/paperclip/thumbnail.rb, line 110 def identified_as_animated? if @identified_as_animated.nil? @identified_as_animated = ANIMATED_FORMATS.include? identify("-format %m :file", :file => "#{@file.path}[0]").to_s.downcase.strip end @identified_as_animated 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