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PNG format Parser in Elixir
defmodule Expng do
defstruct [:width, :height, :bit_depth, :color_type, :compression, :filter, :interlace, :chunks]
def png_parse(<<
0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A,
_length :: size(32),
"IHDR",
width :: size(32),
height :: size(32),
bit_depth,
color_type,
compression_method,
filter_method,
interlace_method,
_crc :: size(32),
chunks :: binary>>) do
png = %Expng{
width: width,
height: height,
bit_depth: bit_depth,
color_type: color_type,
compression: compression_method,
filter: filter_method,
interlace: interlace_method,
chunks: []}
png_parse_chunks(chunks, png)
end
defp png_parse_chunks(<<
length :: size(32),
chunk_type :: size(32),
chunk_data :: binary - size(length),
crc :: size(32),
chunks :: binary>>, png) do
chunk = %{length: length, chunk_type: chunk_type, data: chunk_data, crc: crc}
png = %{png | chunks: [chunk | png.chunks]}
png_parse_chunks(chunks, png)
end
defp png_parse_chunks(<<>>, png) do
%{png | chunks: Enum.reverse(png.chunks)}
end
end
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