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module Paperclip
# Handles thumbnailing images that are uploaded.
class Thumbnail
attr_accessor :file, :current_geometry, :target_geometry, :format, :whiny_thumbnails, :convert_options
# 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_thumbnails+ is true (which it is, by default.
def initialize file, target_geometry, format = nil, convert_options = nil, whiny_thumbnails = true
@file = file
@crop = target_geometry[-1,1] == '#'
@target_geometry = Geometry.parse target_geometry
@current_geometry = Geometry.from_file file
@convert_options = convert_options
@whiny_thumbnails = whiny_thumbnails
@current_format = File.extname(@file.path)
@basename = File.basename(@file.path, @current_format)
@format = format
end
# Creates a thumbnail, as specified in +initialize+, +make+s it, and returns the
# resulting Tempfile.
def self.make file, dimensions, format = nil, convert_options = nil, whiny_thumbnails = true
new(file, dimensions, format, convert_options, whiny_thumbnails).make
end
# Returns true if the +target_geometry+ is meant to crop.
def crop?
@crop
end
# Performs the conversion of the +file+ into a thumbnail. Returns the Tempfile
# that contains the new image.
def make
src = @file
dst = Tempfile.new([@basename, @format].compact.join("."))
dst.binmode
command = <<-end_command
#{ Paperclip.path_for_command('convert') }
"#{ File.expand_path(src.path) }[0]"
#{ transformation_command }
"#{ File.expand_path(dst.path) }"
end_command
success = system(command.gsub(/\s+/, " "))
if success && $?.exitstatus != 0 && @whiny_thumbnails
raise PaperclipError, "There was an error processing this thumbnail"
end
dst
end
# Returns the command ImageMagick's +convert+ needs to transform the image
# into the thumbnail.
def transformation_command
scale, crop = @current_geometry.transformation_to(@target_geometry, crop?)
trans = "-resize \"#{scale}\""
trans << " -crop \"#{crop}\" +repage" if crop
trans << " #{convert_options}" if convert_options
trans
end
end
# Due to how ImageMagick handles its image format conversion and how Tempfile
# handles its naming scheme, it is necessary to override how Tempfile makes
# its names so as to allow for file extensions. Idea taken from the comments
# on this blog post:
# http://marsorange.com/archives/of-mogrify-ruby-tempfile-dynamic-class-definitions
class Tempfile < ::Tempfile
# Replaces Tempfile's +make_tmpname+ with one that honors file extensions.
def make_tmpname(basename, n)
extension = File.extname(basename)
sprintf("%s,%d,%d%s", File.basename(basename, extension), $$, n, extension)
end
end
end
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