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import os
__version__ = '2.3.7'
def default_backend():
"""Get default backend based on the detected platform.
Supports detecting an existing context and standalone contexts.
If no context if found for the platform we return the linux backend.
Example::
# Get the available backend
backend = get_default_backend(standalone=False/True)
# Create an opengl 3.3 context or detect the currently active
# context requiring at least opengl 3.3 support.
ctx = backend(330)
Returns:
A backend object for creating and/or detecting context
"""
PLATFORMS = {'windows', 'linux', 'darwin'}
import platform
target = platform.system().lower()
for known in PLATFORMS:
if target.startswith(known):
target = known
if target not in PLATFORMS:
target = 'linux'
if target == 'windows':
return _wgl()
if target == 'linux':
return _x11()
if target == 'darwin':
return _darwin()
raise ValueError("Cannot find suitable default backend")
def get_backend_by_name(name: str):
"""Request a specific backend by name"""
if name == 'egl':
return _egl()
raise ValueError("Cannot find supported backend: '{}'".format(name))
def _wgl():
"""Create wgl backend"""
from glcontext import wgl
def create(*args, **kwargs):
_apply_env_var(kwargs, 'glversion', 'GLCONTEXT_GLVERSION', arg_type=int)
_apply_env_var(kwargs, 'libgl', 'GLCONTEXT_WIN_LIBGL')
# make sure libgl is an absolute path
if 'libgl' in kwargs:
_libgl = kwargs['libgl']
if '/' in _libgl or '\\' in _libgl:
kwargs['libgl'] = os.path.abspath(_libgl)
kwargs = _strip_kwargs(kwargs, ['glversion', 'mode', 'libgl'])
return wgl.create_context(**kwargs)
return create
def _x11():
"""Create x11 backend"""
from glcontext import x11
from ctypes.util import find_library
def create(*args, **kwargs):
if not kwargs.get('libgl'):
kwargs['libgl'] = find_library('GL')
if not kwargs.get('libx11'):
kwargs['libx11'] = find_library("X11")
_apply_env_var(kwargs, 'glversion', 'GLCONTEXT_GLVERSION', arg_type=int)
_apply_env_var(kwargs, 'libgl', 'GLCONTEXT_LINUX_LIBGL')
_apply_env_var(kwargs, 'libx11', 'GLCONTEXT_LINUX_LIBX11')
kwargs = _strip_kwargs(kwargs, ['glversion', 'mode', 'libgl', 'libx11'])
return x11.create_context(**kwargs)
return create
def _darwin():
"""Create darwin/cgl context"""
from glcontext import darwin
def create(*args, **kwargs):
return darwin.create_context(**_strip_kwargs(kwargs, ['mode']))
return create
def _egl():
from glcontext import egl
from ctypes.util import find_library
def create(*args, **kwargs):
if not kwargs.get('libgl'):
kwargs['libgl'] = find_library('GL')
if not kwargs.get('libegl'):
kwargs['libegl'] = find_library('EGL')
_apply_env_var(kwargs, 'device_index', 'GLCONTEXT_DEVICE_INDEX', arg_type=int)
_apply_env_var(kwargs, 'glversion', 'GLCONTEXT_GLVERSION', arg_type=int)
_apply_env_var(kwargs, 'libgl', 'GLCONTEXT_LINUX_LIBGL')
_apply_env_var(kwargs, 'libegl', 'GLCONTEXT_LINUX_LIBEGL')
kwargs = _strip_kwargs(kwargs, ['glversion', 'mode', 'libgl', 'libegl', 'device_index'])
return egl.create_context(**kwargs)
return create
def _strip_kwargs(kwargs: dict, supported_args: list):
"""Strips away unwanted keyword arguments.
The backends are using ``PyArg_ParseTupleAndKeywords`` to
parse the incoming ``kwargs`` data. It's not well suited
to handle additional arguments.
- Removes None key arguments
- Removes unsupported arguments
"""
return {k: v for k, v in kwargs.items() if v is not None and k in supported_args}
def _apply_env_var(kwargs, arg_name, env_name, arg_type=str):
"""Injects an environment variable into the arg dict if present"""
value = os.environ.get(env_name, kwargs.get(arg_name))
if value:
kwargs[arg_name] = arg_type(value)
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