Class: ChunkyPNG::Chunk::CompressedText

The CompressedText (zTXt) chunk contains keyword/value metadata about the PNG stream. In this chunk, the value is compressed using Deflate compression.

@see ChunkyPNG::Chunk::CompressedText @see ChunkyPNG::Chunk::InternationalText

Methods

content new read

Attributes

keyword	[RW]
value	[RW]

Public Class methods

new(keyword, value)

[Source]

     # File lib/chunky_png/chunk.rb, line 281
281:       def initialize(keyword, value)
282:         super('zTXt')
283:         @keyword, @value = keyword, value
284:       end

read(type, content)

[Source]

     # File lib/chunky_png/chunk.rb, line 286
286:       def self.read(type, content)
287:         keyword, compression, value = content.unpack('Z*Ca*')
288:         raise ChunkyPNG::NotSupported, "Compression method #{compression.inspect} not supported!" unless compression == ChunkyPNG::COMPRESSION_DEFAULT
289:         new(keyword, Zlib::Inflate.inflate(value))
290:       end

Public Instance methods

content()

Creates the content to write to the stream, by concatenating the keyword with the deflated value, joined by a null character.

@return The content that should be written to the datastream.

[Source]

     # File lib/chunky_png/chunk.rb, line 296
296:       def content
297:         [keyword, ChunkyPNG::COMPRESSION_DEFAULT, Zlib::Deflate.deflate(value)].pack('Z*Ca*')
298:       end