8000 Rework backend loading. · matplotlib/matplotlib@a16e3ec · GitHub
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Rework backend loading.
This is preliminary work towards fixing the runtime detection of default backend problem (the first step being to make it easier to check whether a backend *can* be loaded). No publically visible API is changed. Backend loading now defines default versions of `backend_version`, `draw_if_interactive`, and `show` using the same inheritance strategy as builtin backends do. For non-interactive backends (which don't override `mainloop`), restore the default implementation of `show()` that prints a warning when run from a console (the backend refactor accidentally removed this error message as it provided a silent default `show()`). The `_Backend` class had to be moved to the end of the module as `FigureManagerBase` needs to be defined first. The `ShowBase` class had to be moved even after that as it depends on the `_Backend` class.
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‎lib/matplotlib/backend_bases.py‎

Lines changed: 128 additions & 114 deletions
Original file line numberDiff line numberDiff line change
@@ -41,6 +41,7 @@
4141
from contextlib import contextmanager
4242
from functools import partial
4343
import importlib
44+
import inspect
4445
import io
4546
import os
4647
import sys
@@ -49,6 +50,7 @@
4950
from weakref import WeakKeyDictionary
5051

5152
import numpy as np
53+
import matplotlib
5254
import matplotlib.cbook as cbook
5355
import matplotlib.colors as colors
5456
import matplotlib.transforms as transforms
@@ -136,120 +138,6 @@ def get_registered_canvas_class(format):
136138
return backend_class
137139

138140

139-
class _Backend(object):
140-
# A backend can be defined by using the following pattern:
141-
#
142-
# @_Backend.export
143-
# class FooBackend(_Backend):
144-
# # override the attributes and methods documented below.
145-
146-
# The following attributes and methods must be overridden by subclasses.
147-
148-
# The `FigureCanvas` and `FigureManager` classes must be defined.
149-
FigureCanvas = None
150-
FigureManager = None
151-
152-
# The following methods must be left as None for non-interactive backends.
153-
# For interactive backends, `trigger_manager_draw` should be a function
154-
# taking a manager as argument and triggering a canvas draw, and `mainloop`
155-
# should be a function taking no argument and starting the backend main
156-
# loop.
157-
trigger_manager_draw = None
158-
mainloop = None
159-
160-
# The following methods will be automatically defined and exported, but
161-
# can be overridden.
162-
163-
@classmethod
164-
def new_figure_manager(cls, num, *args, **kwargs):
165-
"""Create a new figure manager instance.
166-
"""
167-
# This import needs to happen here due to circular imports.
168-
from matplotlib.figure import Figure
169-
fig_cls = kwargs.pop('FigureClass', Figure)
170-
fig = fig_cls(*args, **kwargs)
171-
return cls.new_figure_manager_given_figure(num, fig)
172-
173-
@classmethod
174-
def new_figure_manager_given_figure(cls, num, figure):
175-
"""Create a new figure manager instance for the given figure.
176-
"""
177-
canvas = cls.FigureCanvas(figure)
178-
manager = cls.FigureManager(canvas, num)
179-
return manager
180-
181-
@classmethod
182-
def draw_if_interactive(cls):
183-
if cls.trigger_manager_draw is not None and is_interactive():
184-
manager = Gcf.get_active()
185-
if manager:
186-
cls.trigger_manager_draw(manager)
187-
188-
@classmethod
189-
def show(cls, block=None):
190-
"""Show all figures.
191-
192-
`show` blocks by calling `mainloop` if *block* is ``True``, or if it
193-
is ``None`` and we are neither in IPython's ``%pylab`` mode, nor in
194-
`interactive` mode.
195-
"""
196-
if cls.mainloop is None:
197-
return
198-
managers = Gcf.get_all_fig_managers()
199-
if not managers:
200-
return
201-
for manager in managers:
202-
manager.show()
203-
if block is None:
204-
# Hack: Are we in IPython's pylab mode?
205-
from matplotlib import pyplot
206-
try:
207-
# IPython versions >= 0.10 tack the _needmain attribute onto
208-
# pyplot.show, and always set it to False, when in %pylab mode.
209-
ipython_pylab = not pyplot.show._needmain
210-
except AttributeError:
211-
ipython_pylab = False
212-
block = not ipython_pylab and not is_interactive()
213-
# TODO: The above is a hack to get the WebAgg backend working with
214-
# ipython's `%pylab` mode until proper integration is implemented.
215-
if get_backend() == "WebAgg":
216-
block = True
217-
if block:
218-
cls.mainloop()
219-
220-
# This method is the one actually exporting the required methods.
221-
222-
@staticmethod
223-
def export(cls):
224-
for name in ["FigureCanvas",
225-
"FigureManager",
226-
"new_figure_manager",
227-
"new_figure_manager_given_figure",
228-
"draw_if_interactive",
229-
"show"]:
230-
setattr(sys.modules[cls.__module__], name, getattr(cls, name))
231-
232-
# For back-compatibility, generate a shim `Show` class.
233-
234-
class Show(ShowBase):
235-
def mainloop(self):
236-
return cls.mainloop()
237-
238-
setattr(sys.modules[cls.__module__], "Show", Show)
239-
return cls
240-
241-
242-
class ShowBase(_Backend):
243-
"""
244-
Simple base class to generate a show() callable in backends.
245-
246-
Subclass must override mainloop() method.
247-
"""
248-
249-
def __call__(self, block=None):
250-
return self.show(block=block)
251-
252-
253141
class RendererBase(object):
254142
"""An abstract base class to handle drawing/rendering operations.
255143
@@ -3375,3 +3263,129 @@ def set_message(self, s):
33753263
Message text
33763264
"""
33773265
pass
3266+
3267+
3268+
class _Backend(object):
3269+
# A backend can be defined by using the following pattern:
3270+
#
3271+
# @_Backend.export
3272+
# class FooBackend(_Backend):
3273+
# # override the attributes and methods documented below.
3274+
3275+
# May be overridden by the subclass.
3276+
backend_version = "unknown"
3277+
# The `FigureCanvas` class must be overridden.
3278+
FigureCanvas = None
3279+
# For interactive backends, the `FigureManager` class must be overridden.
3280+
FigureManager = FigureManagerBase
3281+
# The following methods must be left as None for non-interactive backends.
3282+
# For interactive backends, `trigger_manager_draw` should be a function
3283+
# taking a manager as argument and triggering a canvas draw, and `mainloop`
3284+
# should be a function taking no argument and starting the backend main
3285+
# loop.
3286+
trigger_manager_draw = None
3287+
mainloop = None
3288+
3289+
# The following methods will be automatically defined and exported, but
3290+
# can be overridden.
3291+
3292+
@classmethod
3293+
def new_figure_manager(cls, num, *args, **kwargs):
3294+
"""Create a new figure manager instance.
3295+
"""
3296+
# This import needs to happen here due to circular imports.
3297+
from matplotlib.figure import Figure
3298+
fig_cls = kwargs.pop('FigureClass', Figure)
3299+
fig = fig_cls(*args, **kwargs)
3300+
return cls.new_figure_manager_given_figure(num, fig)
3301+
3302+
@classmethod
3303+
def new_figure_manager_given_figure(cls, num, figure):
3304+
"""Create a new figure manager instance for the given figure.
3305+
"""
3306+
canvas = cls.FigureCanvas(figure)
3307+
manager = cls.FigureManager(canvas, num)
3308+
return manager
3309+
3310+
@classmethod
3311+
def draw_if_interactive(cls):
3312+
if cls.trigger_manager_draw is not None and is_interactive():
3313+
manager = Gcf.get_active()
3314+
if manager:
3315+
cls.trigger_manager_draw(manager)
3316+
3317+
@classmethod
3318+
def show(cls, block=None):
3319+
"""Show all figures.
3320+
3321+
`show` blocks by calling `mainloop` if *block* is ``True``, or if it
3322+
is ``None`` and we are neither in IPython's ``%pylab`` mode, nor in
3323+
`interactive` mode.
3324+
"""
3325+
if cls.mainloop is None:
3326+
frame = inspect.currentframe()
3327+
while frame:
3328+
if frame.f_code.co_filename in [
3329+
"<stdin>", "<ipython console>"]:
3330+
warnings.warn("""\
3331+
Your currently selected backend does not support show().
3332+
Please select a GUI backend in your matplotlibrc file ('{}')
3333+
or with matplotlib.use()""".format(matplotlib.matplotlib_fname()))
3334+
break
3335+
else:
3336+
frame = frame.f_back
3337+
return
3338+
managers = Gcf.get_all_fig_managers()
3339+
if not managers:
3340+
return
3341+
for manager in managers:
3342+
manager.show()
3343+
if block is None:
3344+
# Hack: Are we in IPython's pylab mode?
3345+
from matplotlib import pyplot
3346+
try:
3347+
# IPython versions >= 0.10 tack the _needmain attribute onto
3348+
# pyplot.show, and always set it to False, when in %pylab mode.
3349+
ipython_pylab = not pyplot.show._needmain
3350+
except AttributeError:
3351+
ipython_pylab = False
3352+
block = not ipython_pylab and not is_interactive()
3353+
# TODO: The above is a hack to get the WebAgg backend working with
3354+
# ipython's `%pylab` mode until proper integration is implemented.
3355+
if get_backend() == "WebAgg":
3356+
block = True
3357+
if block:
3358+
cls.mainloop()
3359+
3360+
# This method is the one actually exporting the required methods.
3361+
3362+
@staticmethod
3363+
def export(cls):
3364+
for name in ["backend_version",
3365+
"FigureCanvas",
3366+
"FigureManager",
3367+
"new_figure_manager",
3368+
"new_figure_manager_given_figure",
3369+
"draw_if_interactive",
3370+
"show"]:
3371+
setattr(sys.modules[cls.__module__], name, getattr(cls, name))
3372+
3373+
# For back-compatibility, generate a shim `Show` class.
3374+
3375+
class Show(ShowBase):
3376+
def mainloop(self):
3377+
return cls.mainloop()
3378+
3379+
setattr(sys.modules[cls.__module__], "Show", Show)
3380+
return cls
3381+
3382+
3383+
class ShowBase(_Backend):
3384+
"""
3385+
Simple base class to generate a show() callable in backends.
3386+
3387+
Subclass must override mainloop() method.
3388+
"""
3389+
3390+
def __call__(self, block=None):
3391+
return self.show(block=block)

‎lib/matplotlib/backends/__init__.py‎

Lines changed: 27 additions & 45 deletions
< 4755 tr class="diff-line-row">
Original file line numberDiff line numberDiff line change
@@ -3,11 +3,13 @@
33

44
import six
55

6-
import matplotlib
7-
import inspect
8-
import traceback
9-
import warnings
6+
import importlib
107
import logging
8+
import traceback
9+
10+
import matplotlib
11+
from matplotlib.backend_bases import _Backend
12+
1113

1214
_log = logging.getLogger(__name__)
1315

@@ -47,50 +49,30 @@ def pylab_setup(name=None):
4749
'''
4850
# Import the requested backend into a generic module object
4951
if name is None:
50-
# validates, to match all_backends
5152
name = matplotlib.get_backend()
52-
if name.startswith('module://'):
53-
backend_name = name[9:]
54-
else:
55-
backend_name = 'backend_' + name
56-
backend_name = backend_name.lower() # until we banish mixed case
57-
backend_name = 'matplotlib.backends.%s' % backend_name.lower()
58-
59-
# the last argument is specifies whether to use absolute or relative
60-
# imports. 0 means only perform absolute imports.
61-
backend_mod = __import__(backend_name, globals(), locals(),
62-
[backend_name], 0)
63-
64-
# Things we pull in from all backends
65-
new_figure_manager = backend_mod.new_figure_manager
66-
67-
# image backends like pdf, agg or svg do not need to do anything
68-
# for "show" or "draw_if_interactive", so if they are not defined
69-
# by the backend, just do nothing
70-
def do_nothing_show(*args, **kwargs):
71-
frame = inspect.currentframe()
72-
fname = frame.f_back.f_code.co_filename
73-
if fname in ('<stdin>', '<ipython console>'):
74-
warnings.warn("""
75-
Your currently selected backend, '%s' does not support show().
76-
Please select a GUI backend in your matplotlibrc file ('%s')
77-
or with matplotlib.use()""" %
78-
(name, matplotlib.matplotlib_fname()))
79-
80-
def do_nothing(*args, **kwargs):
81-
pass
82-
83-
backend_version = getattr(backend_mod, 'backend_version', 'unknown')
84-
85-
show = getattr(backend_mod, 'show', do_nothing_show)
86-
87-
draw_if_interactive = getattr(backend_mod, 'draw_if_interactive',
88-
do_nothing)
89-
90-
_log.info('backend %s version %s' % (name, backend_version))
53+
backend_name = (name[9:] if name.startswith("module://")
54+
else "matplotlib.backends.backend_{}".format(name.lower()))
55+
56+
backend_mod = importlib.import_module(backend_name)
57+
Backend = type(str("Backend"), (_Backend,), vars(backend_mod))
58+
_log.info('backend %s version %s', name, Backend.backend_version)
9159

9260
# need to keep a global reference to the backend for compatibility
9361
# reasons. See https://github.com/matplotlib/matplotlib/issues/6092
9462
global backend
9563
backend = name
96-
return backend_mod, new_figure_manager, draw_if_interactive, show
64+
65+
# We want to get functions out of a class namespace and call them *without
66+
# the first argument being an instance of the class*. This works directly
67+
# on Py3. On Py2, we need to remove the check that the first argument be
68+
# an instance of the class. The only relevant case is if `.im_self` is
69+
# None, in which case we need to use `.im_func` (if we have a bound method
70+
# (e.g. a classmethod), everything is fine).
71+
def _dont_check_first_arg(func):
72+
return (func.im_func if getattr(func, "im_self", 0) is None
73+
else func)
74+
75+
return (backend_mod,
76+
_dont_check_first_arg(Backend.new_figure_manager),
77+
_dont_check_first_arg(Backend.draw_if_interactive),
78+
_dont_check_first_arg(Backend.show))

‎lib/matplotlib/backends/backend_pdf.py‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -2599,11 +2599,9 @@ def print_pdf(self, filename, **kwargs):
25992599
file.close()
26002600

26012601

2602-
class FigureManagerPdf(FigureManagerBase):
2603-
pass
2602+
FigureManagerPdf = FigureManagerBase
26042603

26052604

26062605
@_Backend.export
26072606
class _BackendPdf(_Backend):
26082607
FigureCanvas = FigureCanvasPdf
2609-
FigureManager = FigureManagerPdf

‎lib/matplotlib/backends/backend_ps.py‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1728,8 +1728,7 @@ def pstoeps(tmpfile, bbox=None, rotated=False):
17281728
shutil.move(epsfile, tmpfile)
17291729

17301730

1731-
class FigureManagerPS(FigureManagerBase):
1732-
pass
1731+
FigureManagerPS = FigureManagerBase
17331732

17341733

17351734
# The following Python dictionary psDefs contains the entries for the
@@ -1775,4 +1774,3 @@ class FigureManagerPS(FigureManagerBase):
17751774
@_Backend.export
17761775
class _BackendPS(_Backend):
17771776
FigureCanvas = FigureCanvasPS
< 3900 /code>
1778-
FigureManager = FigureManagerPS

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