%% @author Marc Worrell <marc@worrell.nl>
%% @copyright 2009-2014 Marc Worrell
%%
%% @doc Identify files, fetch metadata about an image
%% @todo Recognize more files based on magic number, think of office files etc.
%% Copyright 2009-2014 Marc Worrell, Konstantin Nikiforov
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
-module(z_media_identify).
-author("Marc Worrell <marc@worrell.nl").
%% interface functions
-export([
identify/2,
identify/3,
identify/4,
identify_file/2,
identify_file/3,
identify_file_direct/2,
extension/1,
extension/2,
extension/3,
guess_mime/1,
is_mime_vector/1,
is_mime_compressed/1
]).
-include_lib("zotonic.hrl").
-type optional_filename() :: undefined | file:filename_all().
-type filename_extension() :: binary().
-type mime_type() :: binary().
-type os_family() :: win32 | unix.
-type media_info() :: map().
-export_type([
media_info/0
]).
%% @doc Caching version of identify/3. Fetches information about an image, returns width, height, type, etc.
-spec identify( #upload{} | file:filename_all(), z:context() ) -> {ok, media_info()} | {error, term()}.
identify(#upload{tmpfile=undefined, data=Data, filename=Filename}, Context) when is_binary(Data) ->
TmpFile = z_tempfile:new(),
case file:write_file(TmpFile, Data) of
ok ->
Result = identify_file(TmpFile, Filename, Context),
file:delete(TmpFile),
Result;
{error, _} = Error ->
file:delete(TmpFile),
?LOG_WARNING(#{
text => <<"z_media_identify: could not write temporary file">>,
in => zotonic_core,
size => size(Data),
file => TmpFile
}),
Error
end;
identify(#upload{tmpfile=File, filename=Filename}, Context) ->
% Don't cache identify results for uploaded files
identify_file(File, Filename, Context);
identify(File, Context) ->
identify(File, File, Context).
-spec identify(#upload{}|file:filename_all(), optional_filename(), z:context()) -> {ok, media_info()} | {error, term()}.
identify(File, OriginalFilename, Context) ->
identify(File, File, OriginalFilename, Context).
identify(File, MediumFilename, OriginalFilename, Context) ->
F = fun() ->
case m_media:identify(MediumFilename, Context) of
{ok, _Props} = Result -> Result;
{error, _Reason} -> identify_file(File, OriginalFilename, Context)
end
end,
z_depcache:memo(F, {media_identify, MediumFilename}, ?DAY, [media_identify], Context).
%% @doc Fetch information about a file, returns mime, width, height, type, etc. First checks if a module
%% has a specific identification methods.
-spec identify_file( file:filename_all(), z:context() ) -> {ok, media_info()} | {error, term()}.
identify_file(File, Context) ->
identify_file(File, File, Context).
-spec identify_file( file:filename_all(), optional_filename(), z:context() ) -> {ok, media_info()} | {error, term()}.
identify_file(File, OriginalFilename, Context) ->
Extension = maybe_extension(File, OriginalFilename),
case z_notifier:first(
#media_identify_file{
filename = File,
original_filename = OriginalFilename,
extension = Extension
},
Context)
of
{ok, Props} ->
{ok, Props};
undefined ->
identify_file_direct(File, OriginalFilename)
end.
-spec maybe_extension(file:filename_all(), optional_filename()) -> filename_extension().
maybe_extension(File, undefined) ->
maybe_extension(File);
maybe_extension(_File, OriginalFilename) ->
maybe_extension(OriginalFilename).
-spec maybe_extension( optional_filename() ) -> filename_extension().
maybe_extension(undefined) ->
<<>>;
maybe_extension(Filename) ->
z_convert:to_binary(z_string:to_lower(filename:extension(Filename))).
%% @doc Fetch information about a file, returns mime, width, height, type, etc.
-spec identify_file_direct( file:filename_all(), optional_filename() ) -> {ok, media_info()} | {error, term()}.
identify_file_direct(File, OriginalFilename) ->
check_acceptable(File, maybe_identify_extension(identify_file_direct_1(File, OriginalFilename), OriginalFilename)).
%% Images, pdf and ps are further investigated by ImageMagick
identify_file_direct_1(File, OriginalFilename) ->
OsFamily = os_family(),
case identify_file_os(OsFamily, File, OriginalFilename) of
{error, _} ->
%% Last resort, give ImageMagick a try
identify_file_imagemagick(OsFamily, File, undefined);
{ok, #{ <<"mime">> := <<"image/", _/binary>> = Mime }} ->
identify_file_imagemagick(OsFamily, File, Mime);
{ok, #{ <<"mime">> := <<"application/pdf">> = Mime }} ->
identify_file_imagemagick(OsFamily, File, Mime);
{ok, #{ <<"mime">> := <<"application/postscript">> = Mime }} ->
identify_file_imagemagick(OsFamily, File, Mime);
{ok, Props} = OK when is_map(Props) ->
OK
end.
-spec os_family() -> os_family().
os_family() ->
{OsFamily, _} = os:type(),
OsFamily.
check_acceptable(_File, {error, _} = Error) ->
Error;
check_acceptable(File, {ok, Props}) ->
case z_media_sanitize:is_file_acceptable(File, Props) of
false -> {ok, #{ <<"mime">> => <<"application/octet-stream">> }};
true -> {ok, Props}
end.
maybe_identify_extension({ok, #{ <<"mime">> := <<"application/octet-stream">> }}, OriginalFilename) ->
{ok, #{ <<"mime">> => guess_mime(OriginalFilename) }};
maybe_identify_extension({error, identify}, OriginalFilename) ->
{ok, #{ <<"mime">> => guess_mime(OriginalFilename) }};
maybe_identify_extension(Result, _OriginalFilename) ->
Result.
%% @doc Identify the mime type of a file using the unix "file" command.
-spec identify_file_os(win32|unix, File :: file:filename_all(), OriginalFilename :: file:filename_all()) ->
{ok, media_info()} | {error, term()}.
identify_file_os(win32, _File, OriginalFilename) ->
{ok, #{ <<"mime">> => guess_mime(OriginalFilename)}};
identify_file_os(unix, File, OriginalFilename) ->
identify_file_unix(os:find_executable("file"), File, OriginalFilename).
identify_file_unix(false, _File, _OriginalFilename) ->
?LOG_ERROR("Please install 'file' for identifying the type of uploaded files."),
{error, no_file_cmd};
identify_file_unix(Cmd, File, OriginalFilename) ->
CmdLine = unicode:characters_to_list([
z_filelib:os_filename(Cmd),
" -b --mime-type ",
z_filelib:os_filename(File)
]),
Mime = z_string:trim( unicode:characters_to_binary( os:cmd( CmdLine ) ) ),
case re:run(Mime, "^[a-zA-Z0-9_\\-\\.]+/[a-zA-Z0-9\\.\\-_]+$") of
nomatch ->
case Mime of
<<"CDF V2 Document, corrupt:", _/binary>> ->
% Probably just a semi-illegal variation on a MS Office file, use the extension
case guess_mime(OriginalFilename) of
<<"application/msword">> -> {ok, #{ <<"mime">> => <<"application/msword">>}};
<<"application/vnd.ms-excel">> -> {ok, #{ <<"mime">> => <<"application/vnd.ms-excel">>}};
<<"application/vnd.ms-powerpoint">> -> {ok, #{ <<"mime">> => <<"application/vnd.ms-powerpoint">>}};
_ -> {error, Mime}
end;
_ ->
{error, Mime}
end;
{match, _} ->
case Mime of
<<"text/x-c">> ->
%% "file" does a lousy job recognizing files with curly braces in them.
MXc = case guess_mime(OriginalFilename) of
<<"text/csv">> ->
case z_csv_parser:inspect_file(File) of
{ok, _Hs, _Sep} -> <<"text/csv">>;
{error, _} -> <<"text/plain">>
end;
<<"text/", _/binary>> = MimeFilename -> MimeFilename;
<<"application/x-", _/binary>> = MimeFilename -> MimeFilename;
<<"application/json">> -> <<"application/json">>;
_ -> <<"text/plain">>
end,
{ok, #{ <<"mime">> => MXc}};
<<"text/plain">> ->
MText = case guess_mime(OriginalFilename) of
<<"text/csv">> ->
case z_csv_parser:inspect_file(File) of
{ok, _Hs, _Sep} -> <<"text/csv">>;
{error, _} -> <<"text/plain">>
end;
_ ->
<<"text/plain">>
end,
{ok, #{ <<"mime">> => MText }};
<<"application/x-gzip">> ->
%% Special case for the often used extension ".tgz" instead of ".tar.gz"
MGZip = case filename:extension(OriginalFilename) of
".tgz" -> <<"application/x-gzip+tar">>;
<<".tgz">> -> <<"application/x-gzip+tar">>;
_ -> <<"application/x-gzip">>
end,
{ok, #{ <<"mime">> => MGZip }};
<<"application/zip">> ->
%% Special case for zip'ed office files
MZip = case guess_mime(OriginalFilename) of
<<"application/vnd.openxmlformats-officedocument.", _/binary>> = OfficeMime ->
OfficeMime;
_ ->
<<"application/zip">>
end,
{ok, #{ <<"mime">> => MZip }};
<<"application/ogg">> ->
% The file utility does some miss-guessing
MOgg = case guess_mime(OriginalFilename) of
<<"video/ogg">> -> <<"video/ogg">>;
<<"audio/ogg">> -> <<"audio/ogg">>;
_ -> <<"application/ogg">>
end,
{ok, #{ <<"mime">> => MOgg }};
<<"application/octet-stream">> ->
% The file utility does some miss-guessing
MOctet = case guess_mime(OriginalFilename) of
<<"text/csv">> -> <<"text/csv">>;
<<"application/vnd.oasis.opendocument.", _/binary>> = ODF -> ODF;
<<"application/inspire">> -> <<"application/inspire">>;
<<"video/mpeg">> -> <<"video/mpeg">>;
<<"audio/mpeg">> -> <<"audio/mpeg">>;
_ ->
case identify_magicnumber(File) of
{ok, MagicNumberMime} -> MagicNumberMime;
{error, _} -> <<"application/octet-stream">>
end
end,
{ok, #{ <<"mime">> => MOctet }};
<<"application/vnd.ms-office">> ->
% Generic ms-office mime type, check if the filename is more specific
MOffice = case guess_mime(OriginalFilename) of
<<"application/vnd.ms", _/binary>> = M -> M;
<<"application/msword">> -> <<"application/msword">>;
<<"application/vnd.visio">> -> <<"application/vnd.visio">>;
_ -> <<"application/vnd.ms-office">>
end,
{ok, #{ <<"mime">> => MOffice }};
<<"application/vnd.ms-excel">> = Excel ->
MExcel = case guess_mime(OriginalFilename) of
<<"application/vnd.openxmlformats", _/binary>> = M -> M;
_ -> Excel
end,
{ok, #{ <<"mime">> => MExcel }};
Wav when Wav =:= <<"audio/x-wav">>; Wav =:= <<"audio/wav">> ->
MWav = case guess_mime(OriginalFilename) of
<<"audio/", _/binary>> = M -> M;
_ -> <<"audio/wav">>
end,
{ok, #{ <<"mime">> => MWav }};
<<"audio/x-", _/binary>> ->
MAudio = case guess_mime(OriginalFilename) of
<<"audio/", _/binary>> = M -> M;
_ -> Mime
end,
{ok, #{ <<"mime">> => MAudio }};
<<"video/x-ms-asf">> ->
MAsf = case guess_mime(OriginalFilename) of
<<"audio/", _/binary>> = M -> M;
_ -> <<"video/x-ms-asf">>
end,
{ok, #{ <<"mime">> => MAsf }};
<<"video/mp4">> ->
MMP4 = case guess_mime(OriginalFilename) of
<<"audio/", _/binary>> = M -> M;
_ -> <<"video/mp4">>
end,
{ok, #{ <<"mime">> => MMP4 }};
_ ->
{ok, #{ <<"mime">> => Mime }}
end
end.
%% @doc Try to identify the file using image magick
-spec identify_file_imagemagick(os_family(), file:filename_all(), undefined | mime_type()) -> {ok, media_info()} | {error, term()}.
identify_file_imagemagick(OsFamily, ImageFile, MimeFile) ->
identify_file_imagemagick_1(os:find_executable("identify"), OsFamily, ImageFile, MimeFile).
identify_file_imagemagick_1(false, _OsFamily, _ImageFile, _MimeFile) ->
?LOG_ERROR("Please install ImageMagick 'identify' for identifying the type of uploaded files."),
{error, "'identify' not installed"};
identify_file_imagemagick_1(Cmd, OsFamily, ImageFile, MimeTypeFromFile) ->
CleanedImageFile = z_filelib:os_filename(z_convert:to_list(ImageFile) ++ "[0]"),
CmdOutput = os:cmd(z_filelib:os_filename(Cmd)
++ " -quiet "
++ z_convert:to_list(CleanedImageFile)
++ " 2> " ++ devnull(OsFamily)),
Lines = lists:dropwhile(
fun
("Warning:" ++ _) -> true;
("Can't" ++ _) -> true;
(" ****" ++ _) -> true;
(_) -> false
end,
string:tokens(CmdOutput, "\n")),
case Lines of
[] ->
Err = os:cmd(z_filelib:os_filename(Cmd)
++ " -quiet "
++ z_convert:to_list(CleanedImageFile)
++ " 2>&1"),
?LOG_NOTICE(#{
text => <<"identify of file failed">>,
in => zotonic_core,
file => CleanedImageFile,
result => error,
output => Err
}),
{error, identify};
[Result|_] ->
%% ["test/a.jpg","JPEG","3440x2285","3440x2285+0+0","8-bit","DirectClass","2.899mb"]
%% sometimes:
%% test.jpg[0]=>test.jpg JPEG 2126x1484 2126x1484+0+0 DirectClass 8-bit 836.701kb 0.130u 0:02
%% "/tmp/ztmp-zotonic008prod@miffy.local-1321.452998.868252[0]=>/tmp/ztmp-zotonic008prod@miffy.local-1321.452998.868252 JPEG 1824x1824 1824x1824+0+0 8-bit DirectClass 1.245MB 0.000u 0:00.000"
try
Result1 = z_string:trim( lists:last( binary:split( z_convert:to_binary(Result), z_convert:to_binary(ImageFile), [ global ] ) ) ),
[Type, Dim, _Dim2 | _] = binary:split(Result1, <<" ">>, [ global ]),
Mime = im_mime(Type, MimeTypeFromFile),
[Width,Height] = binary:split( hd( binary:split(Dim, <<"=>">>) ), <<"x">>),
{W1,H1} = maybe_size_correct(Mime, binary_to_integer(Width), binary_to_integer(Height)),
Props1 = #{
<<"width">> => W1,
<<"height">> => H1,
<<"mime">> => Mime
},
Props2 = case Mime of
<<"image/", _/binary>> ->
Exif = exif(ImageFile),
Orientation = exif_orientation(Exif),
Orientation1 = correct_orientation(Orientation, Exif, W1, H1),
Props1#{
<<"orientation">> => Orientation1,
<<"exif">> => Exif,
<<"subject_point">> => exif_subject_point(Exif, Orientation, W1, H1)
};
_ ->
Props1
end,
{ok, Props2}
catch
X:B:Stacktrace ->
?LOG_WARNING(#{
text => <<"identify of file failed">>,
in => zotonic_core,
file => CleanedImageFile,
result => X,
reason => B,
output => CmdOutput,
stack => Stacktrace
}),
{error, identify}
end
end.
%% @doc Prevent unneeded 'extents' for vector based inputs.
maybe_size_correct(Mime, W, H) when W < 3000, H < 3000 ->
case is_mime_vector(Mime) of
true -> {W*2, H*2};
false -> {W,H}
end;
maybe_size_correct(Mime, W, H) when W > 6000; H > 6000 ->
case is_mime_vector(Mime) of
true -> maybe_size_correct(Mime, W div 2, H div 2);
false -> {W,H}
end;
maybe_size_correct(_Mime, W, H) ->
{W, H}.
-spec is_mime_vector( string() | mime_type() ) -> boolean().
is_mime_vector(<<"application/pdf">>) -> true;
is_mime_vector(<<"application/postscript">>) -> true;
is_mime_vector(<<"image/svg+xml">>) -> true;
is_mime_vector(Mime) when is_binary(Mime) -> false;
is_mime_vector(Mime) -> is_mime_vector( z_convert:to_binary(Mime) ).
-spec devnull(win32|unix) -> string().
devnull(win32) -> "nul";
devnull(unix) -> "/dev/null".
%% @doc Map ImageMagick identify to mime_type, special case for PDF/PS files identifying as PBM
%% This is a known problem of IM 6.8.9 (used on Ubuntu 16)
-spec im_mime(binary(), mime_type()|undefined) -> mime_type().
im_mime(<<"PBM">>, MimeFile) when MimeFile =/= undefined -> MimeFile;
im_mime(Type, _) -> mime(Type).
%% @doc Map the type returned by ImageMagick to a mime type
%% @todo Add more imagemagick types, check the mime types
-spec mime( binary() ) -> mime_type().
mime(<<"JPEG">>) -> <<"image/jpeg">>;
mime(<<"GIF">>) -> <<"image/gif">>;
mime(<<"TIFF">>) -> <<"image/tiff">>;
mime(<<"BMP">>) -> <<"image/bmp">>;
mime(<<"PDF">>) -> <<"application/pdf">>;
mime(<<"PS">>) -> <<"application/postscript">>;
mime(<<"PS2">>) -> <<"application/postscript">>;
mime(<<"PS3">>) -> <<"application/postscript">>;
mime(<<"PNG">>) -> <<"image/png">>;
mime(<<"PNG8">>) -> <<"image/png">>;
mime(<<"PNG24">>) -> <<"image/png">>;
mime(<<"PNG32">>) -> <<"image/png">>;
mime(<<"SVG">>) -> <<"image/svg+xml">>;
mime(Type) -> <<"image/", (z_string:to_lower(Type))/binary>>.
% Some PDFs start with a '\t' or whitespace, which causes 'file'
% to mis-guess the filetype.
-spec identify_magicnumber( file:filename_all() ) -> {ok, mime_type()} | {error, term()}.
identify_magicnumber(File) ->
case file:open(File, [read, raw, binary]) of
{ok, Fd} ->
R = file:read(Fd, 10),
ok = file:close(Fd),
case R of
{ok, <<"%PDF", _/binary>>} ->
{ok, <<"application/pdf">>};
{ok, <<Space, "%PDF", _/binary>>} when Space =:= $\t; Space =:= 32 ->
{ok, <<_, Data/binary>>} = file:read_file(File),
ok = file:write_file(File, Data),
{ok, <<"application/pdf">>};
_ ->
{error, unknown}
end;
{error, _} = Error ->
Error
end.
%% @doc Return the extension for a known mime type (eg. ".mov").
-spec extension(Mime) -> filename_extension()
when Mime :: string()
| binary()
| {binary(), binary(), list()}.
extension(Mime) ->
extension(Mime, undefined).
%% @doc Return the extension for a known mime type (eg. ".mov"). When
%% multiple extensions are found for the given mime type, returns the
%% one that is given as the preferred extension. Otherwise, it returns
%% the first extension.
-spec extension(Mime, PreferExtension, z:context()) -> filename_extension()
when Mime :: string()
| binary()
| {binary(), binary(), list()},
PreferExtension :: string()
| binary()
| undefined.
extension(Mime, PreferExtension, Context) when is_binary(Mime) ->
case z_notifier:first(
#media_identify_extension{
mime = maybe_binary(Mime),
preferred = maybe_binary(PreferExtension)},
Context)
of
undefined ->
extension(Mime, PreferExtension);
Extension ->
Extension
end;
extension(Mime, PreferExtension, Context) ->
extension(z_convert:to_binary(Mime), PreferExtension, Context).
maybe_binary(undefined) -> undefined;
maybe_binary({A, B, _}) -> <<A/binary, $/, B/binary>>;
maybe_binary(L) -> z_convert:to_binary(L).
-spec extension(Mime, PreferExtension) -> filename_extension()
when Mime :: string()
| binary()
| {binary(), binary(), list()},
PreferExtension :: string()
| binary()
| undefined.
extension({A, B, _}, PreferExtension) ->
extension(<<A/binary, $/, B/binary>>, PreferExtension);
extension(Mime, PreferExtension) when is_list(Mime) ->
extension(list_to_binary(Mime), PreferExtension);
extension(<<"image/jpeg">>, _PreferExtension) -> <<".jpg">>;
extension(<<"application/vnd.ms-excel">>, _) -> <<".xls">>;
extension(<<"text/plain">>, _PreferExtension) -> <<".txt">>;
extension(<<"audio/wav">>, _PreferExtension) -> <<".wav">>;
extension(<<"audio/x-m4a">>, _PreferExtension) -> <<".m4a">>;
extension(<<"audio/mp4">>, _PreferExtension) -> <<".m4a">>;
extension(<<"audio/mp4a-latm">>, _PreferExtension) -> <<".m4a">>;
extension(<<"application/pgp-keys">>, _PreferExtension) -> <<".asc">>;
extension(<<"application/x-bert">>, _PreferExtension) -> <<".bert">>;
% Fonts have since 2017 their own mime types- https://tools.ietf.org/html/rfc8081#section-4.4.5
extension(<<"font/woff">>, _PreferExtension) -> <<".woff">>;
extension(<<"font/woff2">>, _PreferExtension) -> <<".woff2">>;
extension(<<"font/ttf">>, _PreferExtension) -> <<".ttf">>;
extension(<<"font/eot">>, _PreferExtension) -> <<".eot">>;
extension(<<"font/otf">>, _PreferExtension) -> <<".otf">>;
extension(Mime, undefined) ->
Extensions = mimetypes:extensions(Mime),
first_extension(Extensions);
extension(Mime, PreferExtension) ->
%% convert prefer extension to something that mimetypes likes
Ext1 = z_string:to_lower(PreferExtension),
Ext2 = case Ext1 of
<<$.,Rest/binary>> -> Rest;
_ -> Ext1
end,
Extensions = mimetypes:extensions(Mime),
case lists:member(Ext2, Extensions) of
true -> <<$., Ext2/binary>>;
false -> first_extension(Extensions)
end.
first_extension([]) ->
<<".bin">>;
first_extension([ Ext | _ ]) ->
<<$., Ext/binary>>.
%% @doc Guess the mime type of a file by the extension of its filename.
-spec guess_mime( file:filename_all() ) -> mime_type().
guess_mime(File) ->
case z_string:to_lower( filename:extension( File ) ) of
<<".bert">> -> <<"application/x-bert">>;
% Fonts have since 2017 their own mime types- https://tools.ietf.org/html/rfc8081#section-4.4.5
<<".woff">> -> <<"font/woff">>;
<<".woff2">> -> <<"font/woff2">>;
<<".ttf">> -> <<"font/ttf">>;
<<".eot">> -> <<"font/eot">>;
<<".otf">> -> <<"font/otf">>;
<<".", Ext/binary>> ->
[Mime|_] = mimetypes:ext_to_mimes(Ext),
maybe_map_mime(Mime);
_ ->
<<"application/octet-stream">>
end.
maybe_map_mime(<<"audio/x-wav">>) -> <<"audio/wav">>;
maybe_map_mime(<<"audio/mp4a-latm">>) -> <<"audio/mp4">>;
maybe_map_mime(Mime) -> Mime.
% Fetch the EXIF information from the file, we remove the maker_note as it can be huge
-spec exif( file:filename_all() ) -> map().
exif(File) ->
try
case erlang_exif:read(File, maps) of
{ok, ExifMap} ->
maps:fold(
fun
(maker_note, _Val, Acc) ->
Acc;
(user_comment, _Val, Acc) ->
Acc;
(Tag, Val, Acc) ->
case is_zero_val(Val) of
true ->
Acc;
false ->
Acc#{ atom_to_binary(Tag, utf8) => Val }
end
end,
#{},
ExifMap);
{error, _} ->
#{}
end
catch
A:B:Stacktrace ->
?LOG_ERROR(#{
text => <<"Error reading exif data from file">>,
in => zotonic_core,
result => A,
reason => B,
filename => File,
stack => Stacktrace
}),
#{}
end.
is_zero_val(L) when is_list(L) ->
lists:all(fun(C) -> C =:= 0 end, L);
is_zero_val(L) when is_binary(L) ->
lists:all(fun(C) -> C =:= 0 end, z_convert:to_list(L));
is_zero_val(_) ->
false.
%% Detect the exif rotation in an image and swaps width/height accordingly.
-spec exif_orientation( map() ) -> 1|2|3|4|5|6|7|8.
exif_orientation(#{ <<"orientation">> := <<"Top-left">> }) -> 1;
exif_orientation(#{ <<"orientation">> := <<"Top-right">> }) -> 2;
exif_orientation(#{ <<"orientation">> := <<"Bottom-right">> }) -> 3;
exif_orientation(#{ <<"orientation">> := <<"Bottom-left">> }) -> 4;
exif_orientation(#{ <<"orientation">> := <<"Left-top">> }) -> 5;
exif_orientation(#{ <<"orientation">> := <<"Right-top">> }) -> 6;
exif_orientation(#{ <<"orientation">> := <<"Right-bottom">> }) -> 7;
exif_orientation(#{ <<"orientation">> := <<"Left-bottom">> }) -> 8;
exif_orientation(_) -> 1.
%% See also http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/subjectarea.html
exif_subject_point(Exif, Orientation, Width, Height) ->
Point = extract_subject_point(Exif),
Point1 = maybe_resize_point(Point, Exif, Width, Height),
maybe_rotate(Orientation, Point1, Width, Height).
extract_subject_point(#{ <<"subject_area">> := [ X, Y ] }) -> {X, Y};
extract_subject_point(#{ <<"subject_area">> := [X, Y, _Radius] }) -> {X, Y};
extract_subject_point(#{ <<"subject_area">> := [X, Y, _W, _H] }) -> {X, Y};
extract_subject_point(_) -> undefined.
maybe_resize_point(undefined, _Exif, _Width, _Height) ->
undefined;
maybe_resize_point({X, Y}, Exif, Width, Height) ->
ExifWidth = maps:get(<<"pixel_x_dimension">>, Exif, undefined),
ExifHeight = maps:get(<<"pixel_y_dimension">>, Exif, undefined),
case is_integer(ExifWidth) andalso is_integer(ExifHeight) of
true when ExifWidth =:= Width, ExifHeight =:= Height ->
{X, Y};
true when ExifWidth =:= 0; ExifHeight =:= 0 ->
{X, Y};
true ->
{round(X*Width/ExifWidth), round(Y*Height/ExifHeight)};
false ->
{X, Y}
end.
maybe_rotate(_, undefined, _W, _H) -> undefined;
maybe_rotate(1, {X, Y}, _W, _H) -> {X, Y};
maybe_rotate(2, {X, Y}, _W, H) -> {X, H-Y}; % flip
maybe_rotate(3, {X, Y}, W, H) -> {W-X, H-Y}; % rotate 180
maybe_rotate(4, {X, Y}, W, _H) -> {W-X, Y}; % flop
maybe_rotate(5, {X, Y}, W, H) -> {W-X, H-Y}; % transpose
maybe_rotate(6, {X, Y}, _W, H) -> {H-Y, X}; % rotate 90
maybe_rotate(7, {X, Y}, W, H) -> {W-X, H-Y}; % transverse
maybe_rotate(8, {X, Y}, W, _H) -> {Y, W-X}. % rotate 270
%% @doc Check that the orientation makes sense given the width/height of the image
correct_orientation(1, _Exif, _Width, _Height) ->
1;
correct_orientation(Orientation, Exif, Width, Height) ->
IsLandscape = Width > Height,
ExifWidth = maps:get(<<"pixel_x_dimension">>, Exif, 0),
ExifHeight = maps:get(<<"pixel_y_dimension">>, Exif, 0),
case is_integer(ExifWidth) andalso is_integer(ExifHeight) of
true when IsLandscape, ExifWidth < ExifHeight ->
% The image is landscape, but the exif describes a portrait orientated image
% We assume that the rotation has been done already
1;
true when not IsLandscape, ExifWidth > ExifHeight ->
% The image is portrait, but the exif describes a landscape orientated image.
% We assume that the rotation has been done already
1;
_ ->
Orientation
end.
%% @doc Given a mime type, return whether its file contents is already compressed or not.
-spec is_mime_compressed(binary()) -> boolean().
is_mime_compressed(<<"text/", _/binary>>) -> false;
is_mime_compressed(<<"image/svgz", _/binary>>) -> true;
is_mime_compressed(<<"image/svg", _/binary>>) -> false;
is_mime_compressed(<<"image/", _/binary>>) -> true;
is_mime_compressed(<<"video/", _/binary>>) -> true;
is_mime_compressed(<<"audio/x-wav">>) -> false;
is_mime_compressed(<<"audio/wav">>) -> false;
is_mime_compressed(<<"audio/", _/binary>>) -> true;
is_mime_compressed(<<"application/x-compres", _/binary>>) -> true;
is_mime_compressed(<<"application/zip">>) -> true;
is_mime_compressed(<<"application/x-gz", _/binary>>) -> true;
is_mime_compressed(<<"application/x-rar">>) -> true;
is_mime_compressed(<<"application/x-bzip2">>) -> true;
is_mime_compressed(<<"application/x-font-woff">>) -> true;
is_mime_compressed(<<"application/vnd.oasis.opendocument.", _/binary>>) -> true;
is_mime_compressed(<<"application/vnd.openxml", _/binary>>) -> true;
is_mime_compressed(<<"application/x-shockwave-flash">>) -> true;
is_mime_compressed(_) -> false.
