Figure cannot be closed if it has associated Agg canvas #18163
Description
Bug report
** plt.fignum_exists() returns True after figure is closed**
Code snippet below closes figure after creating FigureCanvasAgg, and it works with matplotlib-3.2.1 but fails with matplotlib-3.3.0
Code for reproduction
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
figure = plt.figure()
plt.axis('scaled')
plt.tight_layout()
matplotlib.backends.backend_agg.FigureCanvasAgg(figure)
plt.close(figure)
print("Matplotlib version:", matplotlib.__version__)
assert plt.fignum_exists(figure.number) == FalseActual outcome
Matplotlib version: 3.3.0
Traceback (most recent call last):
File "figure_exists.py", line 11, in <module>
assert plt.fignum_exists(figure.number) == False
AssertionError
Expected outcome
No assertion, which is easy to reproduce if one to downgrade to matplotlib-3.2.1:
pip3 install matplotlib==3.2.1 --user; python figure_exists.py
Collecting matplotlib==3.2.1
Using cached https://files.pythonhosted.org/packages/b2/c2/71fcf957710f3ba1f09088b35776a799ba7dd95f7c2b195ec800933b276b/matplotlib-3.2.1-cp37-cp37m-manylinux1_x86_64.whl
Requirement already satisfied: pyparsing!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.1 in /usr/lib/python3.7/site-packages (from matplotlib==3.2.1) (2.4.0)
Requirement already satisfied: numpy>=1.11 in /usr/local/lib64/python3.7/site-packages (from matplotlib==3.2.1) (1.18.4)
Requirement already satisfied: python-dateutil>=2.1 in /usr/lib/python3.7/site-packages (from matplotlib==3.2.1) (2.8.0)
Requirement already satisfied: cycler>=0.10 in /usr/lib/python3.7/site-packages (from matplotlib==3.2.1) (0.10.0)
Requirement already satisfied: kiwisolver>=1.0.1 in /usr/lib64/python3.7/site-packages (from matplotlib==3.2.1) (1.1.0)
Requirement already satisfied: six>=1.5 in /usr/lib/python3.7/site-packages (from python-dateutil>=2.1->matplotlib==3.2.1) (1.12.0)
Requirement already satisfied: setuptools in /usr/lib/python3.7/site-packages (from kiwisolver>=1.0.1->matplotlib==3.2.1) (40.8.0)
Installing collected packages: matplotlib
Found existing installation: matplotlib 3.3.0
Uninstalling matplotlib-3.3.0:
Successfully uninstalled matplotlib-3.3.0
Successfully installed matplotlib-3.2.1
Matplotlib version: 3.2.1
Matplotlib version
- Operating system: Fedora Core 30
- Matplotlib version: 3.3.0 (installed via pip as
pip3 install matplotlib==3.3.0 --user) - Matplotlib backend (
print(matplotlib.get_backend())): - Python version: 3.7.0
- Jupyter version (if applicable):
- Other libraries: