Question

有时候我需要调用一个只存在于C中的gtk / gobject函数，但返回一个带有python包装器的对象。以前我使用过基于ctypes的解决方案，效果很好：

http://faq.pygtk.org/index.py?req=show&file=faq23.041.htp

现在我从PyGtk（“import gtk”）开始转向GObject-introspection（“来自gi.repository import Gtk”），我可以使用什么呢？

Answer 1

_PyGObject_API界面在某些时候发生了变化。我需要放弃register_sinkfunc功能。以下作品：

from gi.repository import Gio, GLib
import gi
import ctypes

class _PyGObject_Functions(ctypes.Structure):
   _fields_ = [
       ('register_class',
        ctypes.PYFUNCTYPE(ctypes.c_void_p, ctypes.c_char_p,
                          ctypes.c_int, ctypes.py_object,
                          ctypes.py_object)),
       ('register_wrapper',
        ctypes.PYFUNCTYPE(ctypes.c_void_p, ctypes.py_object)),
       ('lookup_class',
        ctypes.PYFUNCTYPE(ctypes.py_object, ctypes.c_int)),
       ('newgobj',
        ctypes.PYFUNCTYPE(ctypes.py_object, ctypes.c_void_p)),
       ]

class PyGObjectCPAI(object):
   def __init__(self):
       PyCObject_AsVoidPtr = ctypes.pythonapi.PyCObject_AsVoidPtr
       PyCObject_AsVoidPtr.restype = ctypes.c_void_p
       PyCObject_AsVoidPtr.argtypes = [ctypes.py_object]
       addr = PyCObject_AsVoidPtr(ctypes.py_object(
           gi._gobject._PyGObject_API))
       self._api = _PyGObject_Functions.from_address(addr)

   def pygobject_new(self, addr):
       return self._api.newgobj(addr)

capi = PyGObjectCPAI()

从指针获取对象：

obj = capi.pygobject_new(pointer)

从（g）对象获取指针：

pointer = hash(obj)

我必须补充一下，在我的情况下，这并没有帮助我解决我的实际问题。我试图与dconf接口，但dconf返回GVariant类型的值，它不从GObject继承。遗憾的是，PyGI / GObject似乎没有公开必要的函数来将C（* GVariant）变成Python GLib.Variant。我想那时候你必须抛弃你的初始方法并尝试不同的东西。

Answer 2

jdm's answer中的代码与Python 3不兼容。由于CObject在Python 2.7和3.1中是deprecated，并且从3.2开始删除，我将代码调整为使用Capsule（available在2.7和3.1中）：

import ctypes, gi

class _PyGObject_Functions(ctypes.Structure):
    _fields_ = [
        ('register_class',
            ctypes.PYFUNCTYPE(ctypes.c_void_p, ctypes.c_char_p,
                ctypes.c_int, ctypes.py_object, ctypes.py_object)),
        ('register_wrapper',
            ctypes.PYFUNCTYPE(ctypes.c_void_p, ctypes.py_object)),
        ('lookup_class',
            ctypes.PYFUNCTYPE(ctypes.py_object, ctypes.c_int)),
        ('newgobj',
            ctypes.PYFUNCTYPE(ctypes.py_object, ctypes.c_void_p)),
        ]

class PyGObjectCAPI(object):
    def __init__(self):
        self._as_void_ptr.restype = ctypes.c_void_p
        self._as_void_ptr.argtypes = [ctypes.py_object]
        addr = self._as_void_ptr(ctypes.py_object(
            gi._gobject._PyGObject_API))
        self._api = _PyGObject_Functions.from_address(addr)

    @staticmethod
    def _as_void_ptr(obj):
        name = ctypes.pythonapi.PyCapsule_GetName(obj)
        return ctypes.pythonapi.PyCapsule_GetPointer(obj, name)

    def pygobject_new(self, addr):
        return self._api.newgobj(addr)

capi = PyGObjectCAPI()

（我也将它重命名为PyGobjectC API - 不确定CPAI代表什么，但这样对我来说更有意义。）

Answer 3

PyGOject api自AlliedEnvy update

以来发生了变化

import gi
import ctypes
from ctypes import pythonapi

class _PyGObject_Functions(ctypes.Structure):
    _fields_ = [
        ('pygobject_register_class',
            ctypes.PYFUNCTYPE(ctypes.c_void_p)),
        ('pygobject_register_wrapper',
            ctypes.PYFUNCTYPE(ctypes.c_void_p)),
        ('pygobject_lookup_class',
            ctypes.PYFUNCTYPE(ctypes.c_void_p)),
        ('pygobject_new',
            ctypes.PYFUNCTYPE(ctypes.py_object, ctypes.c_void_p)),
        ]

  class PyGObjectCAPI(object):
    def __init__(self):
        addr = self._as_void_ptr(gi._gobject._PyGObject_API)
        self._api = _PyGObject_Functions.from_address(addr)

    @classmethod
    def _capsule_name(cls, capsule):
        pythonapi.PyCapsule_GetName.restype = ctypes.c_char_p
        pythonapi.PyCapsule_GetName.argtypes = [ctypes.py_object]
        return pythonapi.PyCapsule_GetName(capsule)

    @classmethod
    def _as_void_ptr(cls, capsule):
        name = cls._capsule_name(capsule)
        pythonapi.PyCapsule_GetPointer.restype = ctypes.c_void_p
        pythonapi.PyCapsule_GetPointer.argtypes = [
            ctypes.py_object, ctypes.c_char_p]
        return pythonapi.PyCapsule_GetPointer(capsule, name)

    def to_object(self, addr):
        return self._api.pygobject_new(addr)

capi = PyGObjectCAPI()

Answer 4

随着instrospection文件（.typelib，.gir）的出现，无论使用何种语言，都应该可以使用相同的API，也就是说，如果你使用的是C函数，那么API，您可能正在使用仅在内部使用的函数。

从内存地址创建python对象（使用gi.repository）

4 个答案: