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fastimage/lib/fastimage.rb
Janko Marohnić 04d1030756 Always rewind the given IO 
When an error occured when extracting dimensions, rewinding would be
skipped and the code would jump straight to "rescue" statements. We want
that the IO is always rewinded, even in case of errors.

Note that this doesn't affect the return value of the method, because
the return value of a method-level "ensure" is always ignored by Ruby.
2016-03-08 21:09:42 +07:00

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# coding: ASCII-8BIT
# FastImage finds the size or type of an image given its uri.
# It is careful to only fetch and parse as much of the image as is needed to determine the result.
# It does this by using a feature of Net::HTTP that yields strings from the resource being fetched
# as soon as the packets arrive.
#
# No external libraries such as ImageMagick are used here, this is a very lightweight solution to
# finding image information.
#
# FastImage knows about GIF, JPEG, BMP, TIFF, ICO, CUR, PNG, PSD, SVG and WEBP files.
#
# FastImage can also read files from the local filesystem by supplying the path instead of a uri.
# In this case FastImage reads the file in chunks of 256 bytes until
# it has enough. This is possibly a useful bandwidth-saving feature if the file is on a network
# attached disk rather than truly local.
#
# FastImage will automatically read from any object that responds to :read - for
# instance an IO object if that is passed instead of a URI.
#
# FastImage will follow up to 4 HTTP redirects to get the image.
#
# FastImage also provides a reader for the content length header provided in HTTP.
# This may be useful to assess the file size of an image, but do not rely on it exclusively -
# it will not be present in chunked responses for instance.
#
# FastImage accepts additional HTTP headers. This can be used to set a user agent
# or referrer which some servers require. Pass an :http_header argument to specify headers,
# e.g., :http_header => {'User-Agent' => 'Fake Browser'}.
#
# FastImage can give you information about the parsed display orientation of an image with Exif
# data (jpeg or tiff).
#
# === Examples
# require 'fastimage'
#
# FastImage.size("http://stephensykes.com/images/ss.com_x.gif")
# => [266, 56]
# FastImage.type("http://stephensykes.com/images/pngimage")
# => :png
# FastImage.type("/some/local/file.gif")
# => :gif
# File.open("/some/local/file.gif", "r") {|io| FastImage.type(io)}
# => :gif
# FastImage.new("http://stephensykes.com/images/pngimage").content_length
# => 432
# FastImage.new("http://stephensykes.com/images/ExifOrientation3.jpg").orientation
# => 3
#
# === References
# * http://snippets.dzone.com/posts/show/805
# * http://www.anttikupila.com/flash/getting-jpg-dimensions-with-as3-without-loading-the-entire-file/
# * http://pennysmalls.wordpress.com/2008/08/19/find-jpeg-dimensions-fast-in-pure-ruby-no-ima/
# * https://rubygems.org/gems/imagesize
# * https://github.com/remvee/exifr
#
require 'net/https'
require 'addressable/uri'
require 'fastimage/fbr.rb'
require 'delegate'
require 'pathname'
require 'zlib'
class FastImage
attr_reader :size, :type, :content_length, :orientation
attr_reader :bytes_read
class FastImageException < StandardError # :nodoc:
end
class UnknownImageType < FastImageException # :nodoc:
end
class ImageFetchFailure < FastImageException # :nodoc:
end
class SizeNotFound < FastImageException # :nodoc:
end
class CannotParseImage < FastImageException # :nodoc:
end
DefaultTimeout = 2 unless const_defined?(:DefaultTimeout)
LocalFileChunkSize = 256 unless const_defined?(:LocalFileChunkSize)
# Returns an array containing the width and height of the image.
# It will return nil if the image could not be fetched, or if the image type was not recognised.
#
# By default there is a timeout of 2 seconds for opening and reading from a remote server.
# This can be changed by passing a :timeout => number_of_seconds in the options.
#
# If you wish FastImage to raise if it cannot size the image for any reason, then pass
# :raise_on_failure => true in the options.
#
# FastImage knows about GIF, JPEG, BMP, TIFF, ICO, CUR, PNG, PSD, SVG and WEBP files.
#
# === Example
#
# require 'fastimage'
#
# FastImage.size("http://stephensykes.com/images/ss.com_x.gif")
# => [266, 56]
# FastImage.size("http://stephensykes.com/images/pngimage")
# => [16, 16]
# FastImage.size("http://farm4.static.flickr.com/3023/3047236863_9dce98b836.jpg")
# => [500, 375]
# FastImage.size("http://www-ece.rice.edu/~wakin/images/lena512.bmp")
# => [512, 512]
# FastImage.size("test/fixtures/test.jpg")
# => [882, 470]
# FastImage.size("http://pennysmalls.com/does_not_exist")
# => nil
# FastImage.size("http://pennysmalls.com/does_not_exist", :raise_on_failure=>true)
# => raises FastImage::ImageFetchFailure
# FastImage.size("http://stephensykes.com/favicon.ico", :raise_on_failure=>true)
# => [16, 16]
# FastImage.size("http://stephensykes.com/images/squareBlue.icns", :raise_on_failure=>true)
# => raises FastImage::UnknownImageType
# FastImage.size("http://stephensykes.com/favicon.ico", :raise_on_failure=>true, :timeout=>0.01)
# => raises FastImage::ImageFetchFailure
# FastImage.size("http://stephensykes.com/images/faulty.jpg", :raise_on_failure=>true)
# => raises FastImage::SizeNotFound
#
# === Supported options
# [:timeout]
# Overrides the default timeout of 2 seconds. Applies both to reading from and opening the http connection.
# [:raise_on_failure]
# If set to true causes an exception to be raised if the image size cannot be found for any reason.
#
def self.size(uri, options={})
new(uri, options).size
end
# Returns an symbol indicating the image type fetched from a uri.
# It will return nil if the image could not be fetched, or if the image type was not recognised.
#
# By default there is a timeout of 2 seconds for opening and reading from a remote server.
# This can be changed by passing a :timeout => number_of_seconds in the options.
#
# If you wish FastImage to raise if it cannot find the type of the image for any reason, then pass
# :raise_on_failure => true in the options.
#
# === Example
#
# require 'fastimage'
#
# FastImage.type("http://stephensykes.com/images/ss.com_x.gif")
# => :gif
# FastImage.type("http://stephensykes.com/images/pngimage")
# => :png
# FastImage.type("http://farm4.static.flickr.com/3023/3047236863_9dce98b836.jpg")
# => :jpeg
# FastImage.type("http://www-ece.rice.edu/~wakin/images/lena512.bmp")
# => :bmp
# FastImage.type("test/fixtures/test.jpg")
# => :jpeg
# FastImage.type("http://stephensykes.com/does_not_exist")
# => nil
# File.open("/some/local/file.gif", "r") {|io| FastImage.type(io)}
# => :gif
# FastImage.type("test/fixtures/test.tiff")
# => :tiff
# FastImage.type("test/fixtures/test.psd")
# => :psd
#
# === Supported options
# [:timeout]
# Overrides the default timeout of 2 seconds. Applies both to reading from and opening the http connection.
# [:raise_on_failure]
# If set to true causes an exception to be raised if the image type cannot be found for any reason.
#
def self.type(uri, options={})
new(uri, options.merge(:type_only=>true)).type
end
def initialize(uri, options={})
@uri = uri
@options = {
:type_only => false,
:timeout => DefaultTimeout,
:raise_on_failure => false,
:proxy => nil,
:http_header => {}
}.merge(options)
@property = @options[:type_only] ? :type : :size
if uri.respond_to?(:read)
fetch_using_read(uri)
else
begin
@parsed_uri = Addressable::URI.parse(uri)
rescue Addressable::URI::InvalidURIError
fetch_using_file_open
else
if @parsed_uri.scheme == "http" || @parsed_uri.scheme == "https"
fetch_using_http
else
fetch_using_file_open
end
end
end
raise SizeNotFound if @options[:raise_on_failure] && @property == :size && !@size
rescue Timeout::Error, SocketError, Errno::ECONNREFUSED, Errno::EHOSTUNREACH, Errno::ECONNRESET,
ImageFetchFailure, Net::HTTPBadResponse, EOFError, Errno::ENOENT
raise ImageFetchFailure if @options[:raise_on_failure]
rescue NoMethodError # 1.8.7p248 can raise this due to a net/http bug
raise ImageFetchFailure if @options[:raise_on_failure]
rescue UnknownImageType
raise UnknownImageType if @options[:raise_on_failure]
rescue CannotParseImage
if @options[:raise_on_failure]
if @property == :size
raise SizeNotFound
else
raise ImageFetchFailure
end
end
ensure
uri.rewind if uri.respond_to?(:rewind)
end
private
def fetch_using_http
@redirect_count = 0
fetch_using_http_from_parsed_uri
end
def fetch_using_http_from_parsed_uri
http_header = {'Accept-Encoding' => 'identity'}.merge(@options[:http_header])
setup_http
@http.request_get(@parsed_uri.request_uri, http_header) do |res|
if res.is_a?(Net::HTTPRedirection) && @redirect_count < 4
@redirect_count += 1
begin
newly_parsed_uri = Addressable::URI.parse(res['Location'])
# The new location may be relative - check for that
if newly_parsed_uri.scheme != "http" && newly_parsed_uri.scheme != "https"
@parsed_uri.path = res['Location']
else
@parsed_uri = newly_parsed_uri
end
rescue Addressable::URI::InvalidURIError
else
fetch_using_http_from_parsed_uri
break
end
end
raise ImageFetchFailure unless res.is_a?(Net::HTTPSuccess)
@content_length = res.content_length
read_fiber = Fiber.new do
res.read_body do |str|
Fiber.yield str
end
end
case res['content-encoding']
when 'deflate', 'gzip', 'x-gzip'
begin
gzip = Zlib::GzipReader.new(FiberStream.new(read_fiber))
rescue FiberError, Zlib::GzipFile::Error
raise CannotParseImage
end
read_fiber = Fiber.new do
while data = gzip.readline
Fiber.yield data
end
end
end
parse_packets FiberStream.new(read_fiber)
break # needed to actively quit out of the fetch
end
end
def proxy_uri
begin
if @options[:proxy]
proxy = Addressable::URI.parse(@options[:proxy])
else
proxy = ENV['http_proxy'] && ENV['http_proxy'] != "" ? Addressable::URI.parse(ENV['http_proxy']) : nil
end
rescue Addressable::URI::InvalidURIError
proxy = nil
end
proxy
end
def setup_http
proxy = proxy_uri
if proxy
@http = Net::HTTP::Proxy(proxy.host, proxy.port).new(@parsed_uri.host, @parsed_uri.inferred_port)
else
@http = Net::HTTP.new(@parsed_uri.host, @parsed_uri.inferred_port)
end
@http.use_ssl = (@parsed_uri.scheme == "https")
@http.verify_mode = OpenSSL::SSL::VERIFY_NONE
@http.open_timeout = @options[:timeout]
@http.read_timeout = @options[:timeout]
end
def fetch_using_read(readable)
# Pathnames respond to read, but always return the first
# chunk of the file unlike an IO (even though the
# docuementation for it refers to IO). Need to supply
# an offset in this case.
if readable.is_a?(Pathname)
read_fiber = Fiber.new do
offset = 0
while str = readable.read(LocalFileChunkSize, offset)
Fiber.yield str
offset += LocalFileChunkSize
end
end
else
read_fiber = Fiber.new do
while str = readable.read(LocalFileChunkSize)
Fiber.yield str
end
end
end
parse_packets FiberStream.new(read_fiber)
end
def fetch_using_file_open
File.open(@uri) do |s|
fetch_using_read(s)
end
end
def parse_packets(stream)
@stream = stream
begin
result = send("parse_#{@property}")
if result
# extract exif orientation if it was found
if @property == :size && result.size == 3
@orientation = result.pop
else
@orientation = 1
end
instance_variable_set("@#{@property}", result)
else
raise CannotParseImage
end
rescue FiberError
raise CannotParseImage
end
end
def parse_size
@type = parse_type unless @type
send("parse_size_for_#{@type}")
end
module StreamUtil # :nodoc:
def read_byte
read(1)[0].ord
end
def read_int
read(2).unpack('n')[0]
end
def read_string_int
value = []
while read(1) =~ /(\d)/
value << $1
end
value.join.to_i
end
end
class FiberStream # :nodoc:
include StreamUtil
attr_reader :pos
def initialize(read_fiber)
@read_fiber = read_fiber
@pos = 0
@strpos = 0
@str = ''
end
def peek(n)
while @strpos + n - 1 >= @str.size
unused_str = @str[@strpos..-1]
new_string = @read_fiber.resume
raise CannotParseImage if !new_string
# we are dealing with bytes here, so force the encoding
new_string.force_encoding("ASCII-8BIT") if String.method_defined? :force_encoding
@str = unused_str + new_string
@strpos = 0
end
result = @str[@strpos..(@strpos + n - 1)]
end
def read(n)
result = peek(n)
@strpos += n
@pos += n
result
end
end
class IOStream < SimpleDelegator # :nodoc:
include StreamUtil
end
def parse_type
case @stream.peek(2)
when "BM"
:bmp
when "GI"
:gif
when 0xff.chr + 0xd8.chr
:jpeg
when 0x89.chr + "P"
:png
when "II", "MM"
:tiff
when '8B'
:psd
when "\0\0"
# ico has either a 1 (for ico format) or 2 (for cursor) at offset 3
case @stream.peek(3).bytes.to_a.last
when 1 then :ico
when 2 then :cur
end
when "RI"
if @stream.peek(12)[8..11] == "WEBP"
:webp
else
raise UnknownImageType
end
when "<s"
:svg
when "<?"
if @stream.peek(100).include?("<svg")
:svg
else
raise UnknownImageType
end
else
raise UnknownImageType
end
end
def parse_size_for_ico
@stream.read(8)[6..7].unpack('CC').map{|byte| byte == 0 ? 256 : byte }
end
alias_method :parse_size_for_cur, :parse_size_for_ico
def parse_size_for_gif
@stream.read(11)[6..10].unpack('SS')
end
def parse_size_for_png
@stream.read(25)[16..24].unpack('NN')
end
def parse_size_for_jpeg
loop do
@state = case @state
when nil
@stream.read(2)
:started
when :started
@stream.read_byte == 0xFF ? :sof : :started
when :sof
case @stream.read_byte
when 0xe1 # APP1
skip_chars = @stream.read_int - 2
data = @stream.read(skip_chars)
io = StringIO.new(data)
if io.read(4) == "Exif"
io.read(2)
@exif = Exif.new(IOStream.new(io)) rescue nil
end
:started
when 0xe0..0xef
:skipframe
when 0xC0..0xC3, 0xC5..0xC7, 0xC9..0xCB, 0xCD..0xCF
:readsize
when 0xFF
:sof
else
:skipframe
end
when :skipframe
skip_chars = @stream.read_int - 2
@stream.read(skip_chars)
:started
when :readsize
s = @stream.read(3)
height = @stream.read_int
width = @stream.read_int
width, height = height, width if @exif && @exif.rotated?
return [width, height, @exif ? @exif.orientation : 1]
end
end
end
def parse_size_for_bmp
d = @stream.read(32)[14..28]
header = d.unpack("C")[0]
result = if header == 40
d[4..-1].unpack('l<l<')
else
d[4..8].unpack('SS')
end
# ImageHeight is expressed in pixels. The absolute value is necessary because ImageHeight can be negative
[result.first, result.last.abs]
end
def parse_size_for_webp
vp8 = @stream.read(16)[12..15]
len = @stream.read(4).unpack("V")
case vp8
when "VP8 "
parse_size_vp8
when "VP8L"
parse_size_vp8l
when "VP8X"
parse_size_vp8x
else
nil
end
end
def parse_size_vp8
w, h = @stream.read(10).unpack("@6vv")
[w & 0x3fff, h & 0x3fff]
end
def parse_size_vp8l
@stream.read(1) # 0x2f
b1, b2, b3, b4 = @stream.read(4).bytes.to_a
[1 + (((b2 & 0x3f) << 8) | b1), 1 + (((b4 & 0xF) << 10) | (b3 << 2) | ((b2 & 0xC0) >> 6))]
end
def parse_size_vp8x
flags = @stream.read(4).unpack("C")[0]
b1, b2, b3, b4, b5, b6 = @stream.read(6).unpack("CCCCCC")
width, height = 1 + b1 + (b2 << 8) + (b3 << 16), 1 + b4 + (b5 << 8) + (b6 << 16)
if flags & 8 > 0 # exif
# parse exif for orientation
# TODO: find or create test images for this
end
return [width, height]
end
class Exif # :nodoc:
attr_reader :width, :height, :orientation
def initialize(stream)
@stream = stream
parse_exif
end
def rotated?
@orientation >= 5
end
private
def get_exif_byte_order
byte_order = @stream.read(2)
case byte_order
when 'II'
@short, @long = 'v', 'V'
when 'MM'
@short, @long = 'n', 'N'
else
raise CannotParseImage
end
end
def parse_exif_ifd
tag_count = @stream.read(2).unpack(@short)[0]
tag_count.downto(1) do
type = @stream.read(2).unpack(@short)[0]
@stream.read(6)
data = @stream.read(2).unpack(@short)[0]
case type
when 0x0100 # image width
@width = data
when 0x0101 # image height
@height = data
when 0x0112 # orientation
@orientation = data
end
if @width && @height && @orientation
return # no need to parse more
end
@stream.read(2)
end
end
def parse_exif
@start_byte = @stream.pos
get_exif_byte_order
@stream.read(2) # 42
offset = @stream.read(4).unpack(@long)[0]
@stream.read(offset - 8)
parse_exif_ifd
@orientation ||= 1
end
end
def parse_size_for_tiff
exif = Exif.new(@stream)
if exif.rotated?
[exif.height, exif.width, exif.orientation]
else
[exif.width, exif.height, exif.orientation]
end
end
def parse_size_for_psd
@stream.read(26).unpack("x14NN").reverse
end
class Svg # :nodoc:
def initialize(stream)
@stream = stream
parse_svg
end
def width_and_height
if @width && @height
[@width, @height]
elsif @width && @ratio
[@width, @width / @ratio]
elsif @height && @ratio
[@height * @ratio, @height]
end
end
private
def parse_svg
attr_name = []
state = nil
while (char = @stream.read(1)) && state != :stop do
case char
when "="
if attr_name.join =~ /width/i
@stream.read(1)
@width = @stream.read_string_int
return if @height
elsif attr_name.join =~ /height/i
@stream.read(1)
@height = @stream.read_string_int
return if @width
elsif attr_name.join =~ /viewbox/i
values = attr_value.split(/\s/)
@ratio = values[2].to_f / values[3].to_f
end
when /\w/
attr_name << char
when ">"
state = :stop if state == :started
else
state = :started if attr_name.join == "svg"
attr_name.clear
end
end
end
def attr_value
@stream.read(1)
value = []
while @stream.read(1) =~ /([^"])/
value << $1
end
value.join
end
end
def parse_size_for_svg
svg = Svg.new(@stream)
svg.width_and_height
end
end
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