defmodule FormatParser.Image do
alias __MODULE__
@moduledoc """
An Image struct and functions.
The Image struct contains the fields format, width_px, height_px, intrinsics and nature.
"""
defstruct [:format, :width_px, :height_px, nature: :image, intrinsics: %{}]
@doc """
Parses a file and extracts some information from it.
Takes a `binary file` as argument.
Returns a struct which contains all information that has been extracted from the file if the file is recognized.
Returns the following tuple if file not recognized: `{:error, file}`.
"""
def parse({:error, file}) when is_binary(file) do
parse_image(file)
end
def parse(file) when is_binary(file) do
parse_image(file)
end
def parse(result) do
result
end
# credo:disable-for-lines:18 Credo.Check.Refactor.CyclomaticComplexity
defp parse_image(file) do
case file do
<<0x89, "PNG", 0x0D, 0x0A, 0x1A, 0x0A, x::binary>> -> parse_png(x)
<<"BM", x::binary>> -> parse_bmp(x)
<<"GIF89a", x::binary>> -> parse_gif(x)
<<"GIF87a", x::binary>> -> parse_gif(x)
<<0xFF, 0xD8, 0xFF, x::binary>> -> parse_jpeg(x)
<<"II", 0x2A, 0x00, x::binary>> -> parse_tif(x)
<<"MM", 0x00, 0x2A, x::binary>> -> parse_tif(x, true)
<<0x00, 0x00, 0x01, 0x00, x::binary>> -> parse_ico(x)
<<0x00, 0x00, 0x02, 0x00, x::binary>> -> parse_cur(x)
<<"8BPS", x::binary>> -> parse_psd(x)
<<0x97, "JB2", 0x0D, 0x0A, 0x1A, 0x0A, x::binary>> -> parse_jb2(x)
<<"gimp xcf", x::binary>> -> parse_xcf(x)
<<0x76, 0x2F, 0x31, 0x01, x::binary>> -> parse_exr(x)
<<"RIFF", _::binary-size(4), "WEBP", x::binary>> -> parse_webp(x)
_ -> {:error, file}
end
end
defp parse_exr(<<_::binary>>) do
%Image{format: :exr}
end
defp parse_xcf(<<_::binary>>) do
%Image{format: :xcf}
end
defp parse_jb2(<<_::binary>>) do
%Image{format: :jb2}
end
defp parse_webp(<<_::binary>>) do
%Image{format: :webp}
end
defp parse_psd(<<_::size(80), height::size(32), width::size(32), _::binary>>) do
%Image{format: :psd, width_px: width, height_px: height}
end
defp parse_ico(
<<_::size(16), width::size(8), height::size(8), num_color_palette::size(8), 0x00,
color_planes::size(16), bits_per_pixel::size(16), _::binary>>
) do
width_px = if width == 0, do: 256, else: width
height_px = if height == 0, do: 256, else: height
intrinsics = %{
num_color_palette: num_color_palette,
color_planes: color_planes,
bits_per_pixel: bits_per_pixel
}
%Image{
format: :ico,
width_px: width_px,
height_px: height_px,
intrinsics: intrinsics
}
end
defp parse_cur(
<<_::size(16), width::size(8), height::size(8), num_color_palette::size(8), 0x00,
hotspot_horizontal_coords::size(16), hotspot_vertical_coords::size(16), _::binary>>
) do
width_px = if width == 0, do: 256, else: width
height_px = if height == 0, do: 256, else: height
intrinsics = %{
num_color_palette: num_color_palette,
hotspot_horizontal_coords: hotspot_horizontal_coords,
hotspot_vertical_coords: hotspot_vertical_coords
}
%Image{
format: :cur,
width_px: width_px,
height_px: height_px,
intrinsics: intrinsics
}
end
defp parse_tif(<<ifd0_offset::little-integer-size(32), x::binary>>) do
ifd_0 = parse_ifd0(x, shift(ifd0_offset, 8), false)
width = ifd_0[256].value
height = ifd_0[257].value
make =
parse_make_tag(
x,
shift(ifd_0[271][:value], 8),
shift(ifd_0[271][:length], 0)
)
model =
parse_make_tag(
x,
shift(ifd_0[272][:value], 8),
shift(ifd_0[272][:length], 0)
)
date_time =
parse_make_tag(
x,
shift(ifd_0[306][:value], 8),
shift(ifd_0[306][:length], 0)
)
intrinsics = %{
preview_offset: ifd_0[273].value,
preview_byte_count: ifd_0[279].value,
model: model,
date_time: date_time
}
cond do
Regex.match?(~r/canon.+/i, make) ->
%Image{
format: :cr2,
width_px: width,
height_px: height,
intrinsics: intrinsics
}
Regex.match?(~r/nikon.+/i, make) ->
%Image{
format: :nef,
width_px: width,
height_px: height,
intrinsics: intrinsics
}
make == "" ->
%Image{format: :tif, width_px: width, height_px: height}
end
end
defp parse_tif(<<ifd0_offset::big-integer-size(32), x::binary>>, _) do
ifd_0 = parse_ifd0(x, shift(ifd0_offset, 8), true)
width = ifd_0[256].value
height = ifd_0[257].value
make =
parse_make_tag(
x,
shift(ifd_0[271][:value], 8),
shift(ifd_0[271][:length], 0)
)
if Regex.match?(~r/nikon.+/i, make) do
%Image{format: :nef}
else
%Image{format: :tif, width_px: width, height_px: height}
end
end
defp parse_ifd0(<<x::binary>>, offset, big_endian) when big_endian == false do
<<_::size(offset), ifdc::little-integer-size(16), rest::binary>> = x
ifds_sizes = ifdc * 12 * 8
<<ifd_set::size(ifds_sizes), _::binary>> = rest
parse_ifds(<<ifd_set::size(ifds_sizes)>>, big_endian, %{})
end
defp parse_ifd0(<<x::binary>>, offset, big_endian) when big_endian == true do
<<_::size(offset), ifd_count::size(16), rest::binary>> = x
ifds_sizes = ifd_count * 12 * 8
<<ifd_set::size(ifds_sizes), _::binary>> = rest
parse_ifds(<<ifd_set::size(ifds_sizes)>>, big_endian, %{})
end
defp parse_ifds(<<>>, _, accumulator), do: accumulator
defp parse_ifds(<<x::binary>>, big_endian, accumulator) do
ifd = parse_ifd(<<x::binary>>, big_endian)
parse_ifds(ifd.ifd_left, big_endian, Map.merge(ifd, accumulator))
end
defp parse_ifd(
<<tag::little-integer-size(16), _::little-integer-size(16),
length::little-integer-size(32), value::little-integer-size(32), ifd_left::binary>>,
big_endian
)
when big_endian == false do
%{tag => %{tag: tag, length: length, value: value}, ifd_left: ifd_left}
end
defp parse_ifd(
<<tag::size(16), type::size(16), length::size(32), value::size(32), ifd_left::binary>>,
big_endian
)
when big_endian == true and type != 3 do
%{tag => %{tag: tag, length: length, value: value}, ifd_left: ifd_left}
end
defp parse_ifd(
<<tag::size(16), type::size(16), length::size(32), value::size(32), ifd_left::binary>>,
big_endian
)
when big_endian == true and type == 3 do
<<value::size(16), _::binary>> = <<value::size(32)>>
%{tag => %{tag: tag, length: length, value: value}, ifd_left: ifd_left}
end
defp shift(offset, _) when is_nil(offset), do: 0
defp shift(offset, byte), do: (offset - byte) * 8
defp parse_make_tag(<<x::binary>>, offset, len) do
<<_::size(offset), make_tag::size(len), _::binary>> = x
<<make_tag::size(len)>>
end
defp parse_gif(<<width::little-integer-size(16), height::little-integer-size(16), _::binary>>) do
%Image{format: :gif, width_px: width, height_px: height}
end
defp parse_jpeg(<<_::binary>>) do
%Image{format: :jpg}
end
defp parse_bmp(
<<_::size(128), width::little-integer-size(32), height::little-integer-size(32),
_::binary>>
) do
%Image{format: :bmp, width_px: width, height_px: height}
end
defp parse_png(
<<_::size(32), "IHDR", width::size(32), height::size(32), bit_depth, color_type,
compression_method, filter_method, interlace_method, crc::size(32), _::binary>>
) do
intrinsics = %{
bit_depth: bit_depth,
color_type: color_type,
compression_method: compression_method,
filter_method: filter_method,
interlace_method: interlace_method,
crc: crc
}
%Image{
format: :png,
width_px: width,
height_px: height,
intrinsics: intrinsics
}
end
end
