a6fac80e66
* Use libvips instead of ruby-imagespec for reading dimensions of jpeg, png, and gif files. * Copy the code for reading the dimensions of flash files from ruby-imagespec. Fixes an incompatibility between ruby-imagespec and the rubocop gem that prevented us from including rubocop in the Gemfile.
58 lines
2.1 KiB
Ruby
58 lines
2.1 KiB
Ruby
# Adapted from https://github.com/dim/ruby-imagespec/blob/f2f3ce8bb5b1b411f8658e66a891a095261d94c0/lib/image_spec/parser/swf.rb
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# License: https://github.com/dim/ruby-imagespec/blob/master/LICENSE
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class MediaFile::Flash < MediaFile::Image
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def dimensions
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# Read the entire stream into memory because the
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# dimensions aren't stored in a standard location
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contents = file.read.force_encoding("ASCII-8BIT")
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# Our 'signature' is the first 3 bytes
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# Either FWS or CWS. CWS indicates compression
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signature = contents[0..2]
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# SWF version
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version = contents[3].unpack('C').join.to_i
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# Determine the length of the uncompressed stream
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length = contents[4..7].unpack('V').join.to_i
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# If we do, in fact, have compression
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if signature == 'CWS'
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# Decompress the body of the SWF
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body = Zlib::Inflate.inflate( contents[8..length] )
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# And reconstruct the stream contents to the first 8 bytes (header)
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# Plus our decompressed body
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contents = contents[0..7] + body
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end
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# Determine the nbits of our dimensions rectangle
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nbits = contents.unpack('C'*contents.length)[8] >> 3
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# Determine how many bits long this entire RECT structure is
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rectbits = 5 + nbits * 4 # 5 bits for nbits, as well as nbits * number of fields (4)
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# Determine how many bytes rectbits composes (ceil(rectbits/8))
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rectbytes = (rectbits.to_f / 8).ceil
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# Unpack the RECT structure from the stream in little-endian bit order, then join it into a string
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rect = contents[8..(8 + rectbytes)].unpack("#{'B8' * rectbytes}").join
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# Read in nbits incremenets starting from 5
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dimensions = Array.new
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4.times do |n|
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s = 5 + (n * nbits) # Calculate our start index
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e = s + (nbits - 1) # Calculate our end index
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dimensions[n] = rect[s..e].to_i(2) # Read that range (binary) and convert it to an integer
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end
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# The values we have here are in "twips"
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# 20 twips to a pixel (that's why SWFs are fuzzy sometimes!)
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width = (dimensions[1] - dimensions[0]) / 20
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height = (dimensions[3] - dimensions[2]) / 20
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[width, height]
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end
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end
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