sharpetronics/fastimage
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Encapsulate reading in a new class

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Marc-Andre Lafortune 2014-01-29 09:15:28 -05:00
parent e0ba178869
commit 0c613a441d
1 changed files with 43 additions and 26 deletions
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47
lib/fastimage.rb
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@ -225,13 +225,13 @@ class FastImage
raise ImageFetchFailure unless res.is_a?(Net::HTTPSuccess) raise ImageFetchFailure unless res.is_a?(Net::HTTPSuccess)
@read_fiber = Fiber.new do read_fiber = Fiber.new do
res.read_body do |str| res.read_body do |str|
Fiber.yield str Fiber.yield str
end end
end end
parse_packets parse_packets FiberStream.new(read_fiber)
break # needed to actively quit out of the fetch break # needed to actively quit out of the fetch
end end
@ -261,13 +261,13 @@ class FastImage
end end
def fetch_using_read(readable) def fetch_using_read(readable)
@read_fiber = Fiber.new do read_fiber = Fiber.new do
while str = readable.read(LocalFileChunkSize) while str = readable.read(LocalFileChunkSize)
Fiber.yield str Fiber.yield str
end end
end end
parse_packets parse_packets FiberStream.new(read_fiber)
end end
def fetch_using_open_uri def fetch_using_open_uri
@ -276,10 +276,8 @@ class FastImage
end end
end end
def parse_packets def parse_packets(stream)
@str = "" @stream = stream
@strpos = 0
@bytes_delivered = 0
begin begin
result = send("parse_#{@property}") result = send("parse_#{@property}")
@ -298,7 +296,17 @@ class FastImage
send("parse_size_for_#{@type}") send("parse_size_for_#{@type}")
end end
def peek_chars(n) class FiberStream
attr_reader :bytes_delivered
def initialize(read_fiber)
@read_fiber = read_fiber
@bytes_delivered = 0
@strpos = 0
@str = ''
end
def peek(n)
while @strpos + n - 1 >= @str.size while @strpos + n - 1 >= @str.size
unused_str = @str[@strpos..-1] unused_str = @str[@strpos..-1]
new_string = @read_fiber.resume new_string = @read_fiber.resume
@ -314,12 +322,21 @@ class FastImage
result = @str[@strpos..(@strpos + n - 1)] result = @str[@strpos..(@strpos + n - 1)]
end end
def get_chars(n) def read(n)
result = peek_chars(n) result = peek(n)
@strpos += n @strpos += n
@bytes_delivered += n @bytes_delivered += n
result result
end end
end
def peek_chars(n)
@stream.peek(n)
end
def get_chars(n)
@stream.read(n)
end
def get_byte def get_byte
get_chars(1).unpack("C")[0] get_chars(1).unpack("C")[0]
@ -368,12 +385,12 @@ class FastImage
case get_byte case get_byte
when 0xe1 # APP1 when 0xe1 # APP1
skip_chars = get_int - 2 skip_chars = get_int - 2
skip_from = @bytes_delivered skip_from = @stream.bytes_delivered
if get_chars(4) == "Exif" if get_chars(4) == "Exif"
get_chars(2) get_chars(2)
parse_exif parse_exif
end end
get_chars(skip_chars - (@bytes_delivered - skip_from)) get_chars(skip_chars - (@stream.bytes_delivered - skip_from))
:started :started
when 0xe0..0xef when 0xe0..0xef
:skipframe :skipframe
@ -445,7 +462,7 @@ class FastImage
end end
next_offset = get_chars(4).unpack(@long)[0] next_offset = get_chars(4).unpack(@long)[0]
relative_offset = next_offset - (@bytes_delivered - @exif_start_byte) relative_offset = next_offset - (@stream.bytes_delivered - @exif_start_byte)
if relative_offset >= 0 if relative_offset >= 0
get_chars(relative_offset) get_chars(relative_offset)
parse_exif_ifd parse_exif_ifd
@ -453,7 +470,7 @@ class FastImage
end end
def parse_exif def parse_exif
@exif_start_byte = @bytes_delivered @exif_start_byte = @stream.bytes_delivered
get_exif_byte_order get_exif_byte_order