Implement Face loading from memory

[madig]

The fourth PR to tackle loading a font from memory instead of from disk.

• Since we still have to support Python 2(?), testing the file_or_stream argument for being a bytes object won't work, accept a io.BytesIO object instead.
• Implement @rougier's suggestion at https://github.com/rougier/freetype-py/pull/33#issuecomment-167834852. Since loading from a path is the default, I did not add a from_file class method. It would make more sense when Face::__init__ is refactored to not have any logic and just stores what it's given.

Not sure what to do about Face::_filename. it doesn't seem to be used anywhere.

Working on attach_file, I need a test case.

Closes https://github.com/rougier/freetype-py/pull/33, https://github.com/rougier/freetype-py/pull/103, https://github.com/rougier/freetype-py/pull/104

[AppVeyorBot]

:white_check_mark: Build freetype-py 1.0.114 completed (commit https://github.com/rougier/freetype-py/commit/e23a551703 by @madig)

[madig]

Bah. Can't get attaching bytes to work because FT_Open_Args -> memory_base expects c_ubyte when it should be POINTER(c_ubyte), which also doesn't work. Did this ever work?

[anthrotype]

from the CI failures, I think you need to update the multibuild submodule

[AppVeyorBot]

:white_check_mark: Build freetype-py 1.0.115 completed (commit https://github.com/rougier/freetype-py/commit/d301b4d0b1 by @madig)

[madig]

I lost patience with attach_file, no idea what the problem is. Maybe in another PR.

Edit: I have this code:

    def attach_file( self, path_or_stream ):
        if hasattr(path_or_stream, "read"):
            error = self._attach_memory(path_or_stream.read())
        else:
            try:
                u_filename = c_char_p(_encode_filename(path_or_stream))
                error = FT_Attach_File(self._FT_Face, u_filename)
            except UnicodeError:
                with open(path_or_stream, mode="rb") as f:
                    filebody = f.read()
                error = self._attach_memory(filebody)
        if error:
            raise FT_Exception(error)

    def _attach_memory(self, byte_stream):
        parameters = FT_Open_Args()
        parameters.flags = FT_OPEN_MEMORY
        parameters.memory_base = POINTER(FT_Byte)(byte_stream)
        parameters.memory_size = len(byte_stream)
        parameters.stream = None
        error = FT_Attach_Stream(self._FT_Face, parameters)
        if error:
            raise FT_Exception(error)
        self._filebodys.append(byte_stream)  # prevent gc
        return error

This errors with "Invalid argument". Meh.

[AppVeyorBot]

:white_check_mark: Build freetype-py 1.0.116 completed (commit https://github.com/rougier/freetype-py/commit/eb4a387387 by @madig)

[madig]

@rougier Please have a look. Can merge and tag if you give your ok. Do you know what Face::_filename is used for?

[rougier]

@madig what Face::_filename are you referring to exactly?

[madig]

https://github.com/rougier/freetype-py/pull/106/files#diff-c981959bb975a2ca7046d119aeb25b02L990

I removed it in this PR, but maybe you know what it's used for?

[rougier]

I can imagine the idea was to keep the reference to the filename but I'm not sure it is actually used elsewhere.

[madig]

I couldn't find a reference to it in the code 🤔 I can leave it in if it's unclear, but only assign when I think a path is passed in?

[rougier]

Well, if it is not used, maybe it's better to remove it completely.

[madig]

I like your attitude. So! Anything else to do here?

[rougier]

Nope. Let's pull the trigger.