module PNG

Defined in:

Constant Summary

MAGIC = Bytes[137, 80, 78, 71, 13, 10, 26, 10]

MAGIC is the first 8 bytes of a PNG file: "\x89PNG\r\n\x1a\n"

VERSION = {{ (`shards version`).stringify.chomp }}

Class Method Summary

• .read(path : String) : Canvas

  Reads a png stream returns a PNG::Canvas

• .read(io : IO) : Canvas

  Reads a png stream returns a PNG::Canvas

• .write(path : String, canvas : Canvas, &heuristic : Scanline | Nil, Scanline -> Scanline)

  Write a canvas to a .png file given a path

• .write(io : IO, canvas : Canvas, &heuristic : Scanline | Nil, Scanline -> Scanline)

  Write a canvas to a given io in png format.

• .write(path : String, canvas : Canvas)
• .write(io : IO, canvas : Canvas)

Macro Summary

• debug(args)

  Only logs messages if built with -Dpng-debug

Class Method Detail

canvas = PNG.read("examples/gradient.png")
canvas.header.color_type # => PNG::ColorType::RGB
canvas[0, 0]             # => Bytes[0, 255, 0]

canvas = PNG.read("examples/gradient.png")
canvas.header.color_type # => PNG::ColorType::RGB
canvas[0, 0]             # => Bytes[0, 255, 0]

canvas = PNG::Canvas.new(255, 255)
0.upto(canvas.height - 1) do |y|
  0.upto(canvas.width - 1) do |x|
    canvas[x, y] = Bytes[x, 255, y]
  end
end

PNG.write("examples/gradient.png", canvas)

Macro Detail