Module: ChunkyPNG::Canvas::PNGEncoding

Included in:
ChunkyPNG::Canvas
Defined in:
lib/chunky_png/canvas/png_encoding.rb

Overview

Methods for encoding a Canvas into a PNG datastream

Constant Summary collapse

TRUECOLOR_ENCODER = 
lambda { |color| Color.to_truecolor_bytes(color) }
TRUECOLOR_ALPHA_ENCODER = 
lambda { |color| Color.to_truecolor_alpha_bytes(color) }
GRAYSCALE_ENCODER = 
lambda { |color| Color.to_grayscale_bytes(color) }
GRAYSCALE_ALPHA_ENCODER = 
lambda { |color| Color.to_grayscale_alpha_bytes(color) }

Instance Method Summary collapse

Instance Method Details

#save(filename, constraints = {}) ⇒ Object 



17
18
19
 
# File 'lib/chunky_png/canvas/png_encoding.rb', line 17

def save(filename, constraints = {})
  File.open(filename, 'wb') { |io| write(io, constraints) }
end

#to_blob(constraints = {}) ⇒ Object Also known as: to_string, to_s 



21
22
23
 
# File 'lib/chunky_png/canvas/png_encoding.rb', line 21

def to_blob(constraints = {})
  to_datastream(constraints).to_blob
end

#to_datastream(constraints = {}) ⇒ Object

Converts this Canvas to a datastream, so that it can be saved as a PNG image.

Parameters:

  • constraints (Hash) (defaults to: {}) —

    The constraints to use when encoding the canvas.



30
31
32
33
34
35
36
37
38
39
 
# File 'lib/chunky_png/canvas/png_encoding.rb', line 30

def to_datastream(constraints = {})
  data = encode_png(constraints)
  ds = Datastream.new
  ds.header_chunk       = Chunk::Header.new(data[:header])
  ds.palette_chunk      = data[:palette_chunk]      if data[:palette_chunk]
  ds.transparency_chunk = data[:transparency_chunk] if data[:transparency_chunk]
  ds.data_chunks        = Chunk::ImageData.split_in_chunks(data[:pixelstream])
  ds.end_chunk          = Chunk::End.new
  return ds
end

#write(io, constraints = {}) ⇒ Object 



13
14
15
 
# File 'lib/chunky_png/canvas/png_encoding.rb', line 13

def write(io, constraints = {})
  to_datastream(constraints).write(io)
end