Allow instantiation with file objects. (#103)

README.md

@@ -26,6 +26,10 @@ Just import the font class:
 from fontbro import Font
 
 font = Font("fonts/MyFont.ttf")
+
+# or you can use any file-like object:
+with open("fonts/MyFont.ttf") as fh:
+    font = Font(fh)
 ```
 
 ### Methods
@@ -65,6 +69,7 @@ font = Font("fonts/MyFont.ttf")
 -   [`save`](#save)
 -   [`save_as_woff`](#save_as_woff)
 -   [`save_as_woff2`](#save_as_woff2)
+-   [`save_to_file_object`](#save_to_file_object)
 -   [`set_name`](#set_name)
 -   [`set_names`](#set_names)
 -   [`set_style_flag`](#set_style_flag)
@@ -548,6 +553,21 @@ Saves font as woff2.
 saved_font_path = font.save_as_woff2(filepath=None, overwrite=True)
 ```
 
+#### `save_to_fileobject`
+```python
+"""
+Writes the font to a file-like object. If no file-object is passed, an
+instance of `BytesIO` is created for the user.
+:param fileobject: A file-like object to write to.
+
+:returns: The file object that was originally pass, or a new BytesIO
+instance.
+:rtype: typing.io.IO
+"""
+
+fileobject = font.save_to_fileobject(fileobject=None)
+```
+
 #### `set_name`
 ```python
 """

fontbro/font.py

@@ -4,6 +4,7 @@
 import sys
 import tempfile
 from curses import ascii
+from io import BytesIO
 from pathlib import Path
 
 import fsutil
@@ -213,11 +214,14 @@ def __init__(self, filepath, **kwargs):
         super().__init__()
 
         self._filepath = None
+        self._fileobject = None
         self._kwargs = None
         self._ttfont = None
 
         if isinstance(filepath, (Path, str)):
             self._init_with_filepath(str(filepath), **kwargs)
+        elif hasattr(filepath, "read"):
+            self._init_with_fileobject(filepath, **kwargs)
         else:
             filepath_type = type(filepath).__name__
             raise ValueError(
@@ -233,6 +237,15 @@ def _init_with_filepath(self, filepath, **kwargs):
         except TTLibError as error:
             raise ValueError(f"Invalid font at filepath: {filepath!r}.") from error
 
+    def _init_with_fileobject(self, fileobject, **kwargs):
+        try:
+            self._fileobject = fileobject
+            self._kwargs = kwargs
+            self._ttfont = TTFont(self._fileobject, **kwargs)
+
+        except TTLibError as error:
+            raise ValueError(f"Invalid font at fileobject: {fileobject!r}.") from error
+
     def __enter__(self):
         return self
 
@@ -1001,7 +1014,15 @@ def save(self, filepath=None, overwrite=False):
 
         :raises ValueError: If the filepath is the same of the source font
         and overwrite is not allowed.
+
+        :raises ValueError: If the font was created from a file object, and filepath is
+        not specififed.
         """
+        if not filepath and not self._filepath:
+            raise ValueError(
+                "Font doesn't have a filepath. Please specify a filepath to save to."
+            )
+
         if filepath is None:
             filepath = self._filepath
 
@@ -1075,6 +1096,22 @@ def save_as_woff2(self, filepath=None, overwrite=True):
             flavor=self.FORMAT_WOFF2, filepath=filepath, overwrite=overwrite
         )
 
+    def save_to_fileobject(self, fileobject=None):
+        """
+        Writes the font to a file-like object. If no file-object is passed, an
+        instance of `BytesIO` is created for the user.
+        :param fileobject: A file-like object to write to.
+
+        :returns: The file object that was originally pass, or a new BytesIO
+        instance.
+        :rtype: typing.io.IO
+        """
+        font = self.get_ttfont()
+        if fileobject is None:
+            fileobject = BytesIO()
+        font.save(fileobject)
+        return fileobject
+
     def set_name(self, key, value):
         """
         Sets the name by its identifier in the font name table.

tests/test_init.py

@@ -1,3 +1,4 @@
+from io import BytesIO
 from pathlib import Path
 
 from fontbro import Font
@@ -20,6 +21,16 @@ def test_init_with_filepath_using_pathlib_path(self):
         filepath = dirpath / Path("Noto_Sans_TC/NotoSansTC-Regular.otf")
         Font(filepath=filepath)
 
+    def test_init_with_file_object(self):
+        filepath = self._get_font_path("/Noto_Sans_TC/NotoSansTC-Regular.otf")
+        with open(filepath, "rb") as fh:
+            Font(fh)
+
+    def test_init_with_file_object_but_invalid_font_file(self):
+        empty = BytesIO()
+        with self.assertRaises(ValueError):
+            Font(empty)
+
     def test_init_with_filepath_but_invalid_font_file(self):
         with self.assertRaises(ValueError):
             filepath = self._get_font_path("/Noto_Sans_TC/OFL.txt")

tests/test_save.py

@@ -1,3 +1,5 @@
+from io import BytesIO
+
 from fontbro import Font
 from tests import AbstractTestCase
 
@@ -23,6 +25,38 @@ def test_save_with_font_src_path_as_filepath_without_overwrite(self):
         with self.assertRaises(ValueError):
             font.save(font_filepath)
 
+    def test_save_fileobject(self):
+        font_filepath = self._get_font_path("/Noto_Sans_TC/NotoSansTC-Regular.otf")
+        with open(font_filepath, "rb") as fh:
+            font = Font(fh)
+            font_saved_path = font.save(font_filepath, overwrite=True)
+            self.assertEqual(font_saved_path, font_filepath)
+
+    def test_save_fileobject_error(self):
+        filepath = self._get_font_path("/Noto_Sans_TC/NotoSansTC-Regular.otf")
+        with open(filepath, "rb") as fh:
+            font = Font(fh)
+            with self.assertRaises(ValueError):
+                font.save()
+
+    def test_save_to_fileobject(self):
+        font = self._get_font("/Roboto_Mono/static/RobotoMono-Regular.ttf")
+        buf = BytesIO()
+        returned = font.save_to_fileobject(buf)
+        returned.seek(0)
+        content = returned.read()
+        # 00 01 00 00 00 is the file signature for TrueType fonts
+        self.assertEqual(content[:5], b"\x00\x01\x00\x00\x00")
+        self.assertIs(buf, returned)
+
+    def test_save_to_fileobject_new(self):
+        font = self._get_font("/Roboto_Mono/static/RobotoMono-Regular.ttf")
+        returned = font.save_to_fileobject()
+        returned.seek(0)
+        content = returned.read()
+        # 00 01 00 00 00 is the file signature for TrueType fonts
+        self.assertEqual(content[:5], b"\x00\x01\x00\x00\x00")
+
     def test_save_as_woff(self):
         # font = self._get_font('/Noto_Sans_TC/NotoSansTC-Regular.otf')
         font = self._get_font("/Roboto_Mono/static/RobotoMono-Regular.ttf")