Erlang EXIF Library

Building and Testing

Prerequisites

• Erlang/OTP 18 or higher.

To build the application and run the test suite, use the Makefile like so:

$ make
$ make test

Usage

To add erlang_exif as a dependency to your rebar-based project, simply add the following to your rebar.config file, then run the ./rebar3 upgrade command to retrieve it.

{deps, [
    {erlang_exif, "3.0.0"}
]}.

Example

The erlang_exif:read(Path) function actually calls erlang_exif:read(Path, map).

The erlang_exif:read(Path, ReturnType) function returns {ok, Exif} where Exif is a dict:dict() or a map of the values read from the JPEG image. ReturnType has two valid values: dict and maps. If no such values are present, the structure will be empty. However, if there was an error, an {error, Reason} tuple will be returned, where Reason is nearly always invalid_exif.

case erlang_exif:read(Path, dict) of
    {error, Reason} ->
        error_logger:error_msg("Unable to read EXIF data from ~s, ~p~n", [Path, Reason]);
    {ok, ExifData} ->
        case dict:find(date_time_original, ExifData) of
            {ok, Original} ->
                % do something with the date...
                ok;
            error ->
                error_logger:info_msg("No original date available")
        end
end.

Two more functions are present: erlang_exif:read_binary/1 and erlang_exif:read_binary/2 which are equivalents of erlang_exif:read/1,2. They accept actual file in binary format as a first argument, instead of a path.