Class: ChunkyPNG::Chunk::End

Inherits:

Base

• Object
• Base
• ChunkyPNG::Chunk::End

Defined in:

lib/chunky_png/chunk.rb

Overview

The End (IEND) chunk indicates the last chunk of a PNG stream. It does not contain any data.

See Also:

• https://www.w3.org/TR/PNG/#11IEND

Instance Attribute Summary

Attributes inherited from Base

#type

Class Method Summary

• .read(type, content) ⇒ ChunkyPNG::Chunk::End

  Reads the END chunk.

Instance Method Summary

• #content ⇒ ""

  Returns an empty string, because this chunk should always be empty.

• #initialize ⇒ End constructor

  A new instance of End.

Methods inherited from Base

#write, #write_with_crc

Constructor Details

#initialize ⇒ End

Returns a new instance of End.

# File 'lib/chunky_png/chunk.rb', line 176

def initialize
  super("IEND")
end

Class Method Details

.read(type, content) ⇒ ChunkyPNG::Chunk::End

Reads the END chunk. It will check if the content is empty.

Parameters:

• type (String) —

  The four character chunk type indicator (= “IEND”).

• content (String) —

  The content read from the chunk. Should be empty.

Returns:

• (ChunkyPNG::Chunk::End) —

  The new End chunk instance.

Raises:

• (ChunkyPNG::ExpectationFailed) —

  Raises an exception if the content was not empty.

# File 'lib/chunky_png/chunk.rb', line 187

def self.read(type, content)
  raise ExpectationFailed, "The IEND chunk should be empty!" if content.bytesize > 0
  new
end

Instance Method Details

#content ⇒ ""

Returns an empty string, because this chunk should always be empty.

Returns:

• ("") —

  An empty string.

# File 'lib/chunky_png/chunk.rb', line 194

def content
  "".b
end