Add android provider (#3)

* Add an android font filename provider
* Bump version to 0.1.0

README.md

@@ -5,6 +5,7 @@ It uses some APIs to find the font filename:
 - Windows: [DirectWrite API](https://learn.microsoft.com/en-us/windows/win32/directwrite/direct-write-portal)
 - macOS: [Core Text API](https://developer.apple.com/documentation/coretext)
 - Linux: [Fontconfig API](https://www.freedesktop.org/wiki/Software/fontconfig/)
+- Android: [NDK Font API](https://developer.android.com/ndk/reference/group/font)
 
 ## Installation
 ```
@@ -13,15 +14,17 @@ pip install FindSystemFontsFilename
 
 ## How to use it
 ```python
-from find_system_fonts_filename import get_system_fonts_filename, FontConfigNotFound, OSNotSupported
+from find_system_fonts_filename import AndroidLibraryNotFound, get_system_fonts_filename, FontConfigNotFound, OSNotSupported
 
 try:
     fonts_filename = get_system_fonts_filename()
-except (FontConfigNotFound, OSNotSupported):
+except (AndroidLibraryNotFound, FontConfigNotFound, OSNotSupported):
     # Deal with the exception
-    # OSNotSupported can only happen in Windows and macOS
+    # OSNotSupported can only happen in Windows, macOS and Android
     #   - Windows Vista SP2 and more are supported
     #   - macOS 10.6 and more are supported
+    #   - Android SDK/API 29 and more are supported
     # FontConfigNotFound can only happen on Linux when Fontconfig could't be found.
+    # AndroidLibraryNotFound can only happen on Android when the android library could't be found.
     pass
 ```

find_system_fonts_filename/__init__.py

@@ -1,4 +1,4 @@
 from .fonts_filename import get_system_fonts_filename
-from .exceptions import FontConfigNotFound, OSNotSupported
+from .exceptions import AndroidLibraryNotFound, FontConfigNotFound, OSNotSupported
 
-__version__ = "0.0.4"
+__version__ = "0.1.0"

find_system_fonts_filename/android_fonts.py

@@ -0,0 +1,93 @@
+from contextlib import contextmanager
+from ctypes import c_char_p, c_void_p, cdll, util
+from os import close, devnull, dup, dup2, O_WRONLY, open
+from sys import stderr, stdout
+from typing import Set
+from .exceptions import AndroidLibraryNotFound, OSNotSupported
+from .system_fonts import SystemFonts
+
+
+class AndroidFonts(SystemFonts):
+    _android = None
+
+    def get_system_fonts_filename() -> Set[str]:
+        if AndroidFonts._android is None:
+             AndroidFonts._load_android_library()
+
+        fonts_filename = set()
+
+        # Redirect the stderr_and_stdout to null since we don't care about android logs
+        # There is __android_log_set_minimum_priority to set the log level, but even if I set it to 8 (which correspond to ANDROID_LOG_SILENT),
+        #   it was still logging: https://developer.android.com/ndk/reference/group/logging#__android_log_set_minimum_priority
+        with AndroidFonts._silence_stderr_and_stdout():
+            font_iterator = AndroidFonts._android.ASystemFontIterator_open()
+
+            while True:
+                font = AndroidFonts._android.ASystemFontIterator_next(font_iterator)
+
+                if font is None:
+                    break
+
+                font_filename = AndroidFonts._android.AFont_getFontFilePath(font).decode("utf-8")
+                fonts_filename.add(font_filename)
+
+                AndroidFonts._android.AFont_close(font)
+            AndroidFonts._android.ASystemFontIterator_close(font_iterator)
+
+        return fonts_filename
+
+    @staticmethod
+    def _load_android_library():
+        android_library_name = util.find_library("android")
+
+        if android_library_name is None:
+            raise AndroidLibraryNotFound("You need to have the libandroid library. It is only available since the SDK/API level 29.")
+
+        AndroidFonts._android = cdll.LoadLibrary(android_library_name)
+
+        # The android device need to be at least on the level 29.
+        # The function android_get_device_api_level is only available since the level 29, so we can't use it. See: https://developer.android.com/ndk/reference/group/apilevels#android_get_device_api_level
+        # So, we try and see if the function are available
+        try:
+            # https://developer.android.com/ndk/reference/group/font#asystemfontiterator_open
+            AndroidFonts._android.ASystemFontIterator_open.restype = c_void_p
+            AndroidFonts._android.ASystemFontIterator_open.argtypes = []
+        except AttributeError:
+            raise OSNotSupported("FindSystemFontsFilename only works on Android API level 29 or more.")
+
+        # https://developer.android.com/ndk/reference/group/font#asystemfontiterator_next
+        AndroidFonts._android.ASystemFontIterator_next.restype = c_void_p
+        AndroidFonts._android.ASystemFontIterator_next.argtypes = [c_void_p]
+
+        # https://developer.android.com/ndk/reference/group/font#asystemfontiterator_close
+        AndroidFonts._android.ASystemFontIterator_close.restype = None
+        AndroidFonts._android.ASystemFontIterator_close.argtypes = [c_void_p]
+
+        # https://developer.android.com/ndk/reference/group/font#afont_getfontfilepath
+        AndroidFonts._android.AFont_getFontFilePath.restype = c_char_p
+        AndroidFonts._android.AFont_getFontFilePath.argtypes = [c_void_p]
+
+        # https://developer.android.com/ndk/reference/group/font#afont_close
+        AndroidFonts._android.AFont_close.restype = None
+        AndroidFonts._android.AFont_close.argtypes = [c_void_p]
+
+    @contextmanager
+    def _silence_stderr_and_stdout():
+        # From: https://stackoverflow.com/a/75037627/15835974
+        stderr_fd = stderr.fileno()
+        orig_stderr_fd = dup(stderr_fd)
+
+        stdout_fd = stdout.fileno()
+        orig_stdout_fd = dup(stdout_fd)
+
+        null_fd = open(devnull, O_WRONLY)
+        dup2(null_fd, stderr_fd)
+        dup2(null_fd, stdout_fd)
+        try:
+            yield
+        finally:
+            dup2(orig_stderr_fd, stderr_fd)
+            dup2(orig_stdout_fd, stdout_fd)
+            close(orig_stderr_fd)
+            close(orig_stdout_fd)
+            close(null_fd)

find_system_fonts_filename/exceptions.py

@@ -4,5 +4,10 @@ class OSNotSupported(Exception):
 
 
 class FontConfigNotFound(Exception):
-    "Raised when a Fontconfig API haven't been found"
-    pass
+    "Raised when the Fontconfig API haven't been found"
+    pass
+
+
+class AndroidLibraryNotFound(Exception):
+    "Raised when the android library haven't been found"
+    pass

find_system_fonts_filename/fonts_filename.py

@@ -1,17 +1,24 @@
 from platform import system
+from os import environ
+from typing import Set
 from .exceptions import OSNotSupported
 
 
-def get_system_fonts_filename():
+def get_system_fonts_filename() -> Set[str]:
     system_name = system()
 
     if system_name == "Windows":
         from .windows_fonts import WindowsFonts
         return WindowsFonts.get_system_fonts_filename()
 
     elif system_name == "Linux":
-        from .linux_fonts import LinuxFonts
-        return LinuxFonts.get_system_fonts_filename()
+        # ANDROID_ROOT or ANDROID_BOOTLOGO - https://stackoverflow.com/a/66174754/15835974
+        if any(t in environ.values() for t in ("ANDROID_ROOT", "ANDROID_BOOTLOGO")):
+            from .android_fonts import AndroidFonts
+            return AndroidFonts.get_system_fonts_filename()
+        else:
+            from .linux_fonts import LinuxFonts
+            return LinuxFonts.get_system_fonts_filename()
 
     elif system_name == "Darwin":
         from .mac_fonts import MacFonts