8000 MNT: add warning if crossing Qt major versions · matplotlib/matplotlib@507bff4 · GitHub
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MNT: add warning if crossing Qt major versions
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2 files changed

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‎lib/matplotlib/backends/backend_qt.py

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -114,6 +114,28 @@ def _create_qApp():
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QtCore.Qt.AA_EnableHighDpiScaling)
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except AttributeError: # Only for Qt>=5.6, <6.
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pass
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# Check to make sure a QApplication from a different major version
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# of Qt is not instantiated in the process
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if QT_API in {'PyQt6', 'PySide6'}:
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other_bindings = ('PyQt5', 'PySide2')
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elif QT_API in {'PyQt5', 'PySide2'}:
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other_bindings = ('PyQt6', 'PySide6')
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else:
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raise RuntimeError("Should never be here")
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for binding in other_bindings:
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mod = sys.modules.get(f'{binding}.QtWidgets')
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if mod is not None and mod.QApplication.instance() is not None:
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other_core = sys.modules.get(f'{binding}.QtCore')
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_api.warn_external(
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f'Matplotlib is using {QT_API} which wraps '
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f'{QtCore.qVersion()} however an instantiated '
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f'QApplication from {binding} which wraps '
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f'{other_core.qVersion()} exists. Mixing Qt major '
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'versions may not work as expected.'
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)
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break
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try:
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QtWidgets.QApplication.setHighDpiScaleFactorRoundingPolicy(
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QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough)

‎lib/matplotlib/tests/test_backends_interactive.py

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@
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from matplotlib import _c_internal_utils
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from matplotlib.testing import subprocess_run_helper as _run_helper
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# Minimal smoke-testing of the backends for which the dependencies are
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# PyPI-installable on CI. They are not available for all tested Python
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# versions so we don't fail on missing backends.
@@ -307,6 +308,50 @@ def test_qt5backends_uses_qt5():
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_run_helper(__name__, _implcore, timeout=_test_timeout)
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309310

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def _impl_test_cross_Qt_imports():
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import sys
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import importlib
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import pytest
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_, host_binding, mpl_binding = sys.argv
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# import the mpl binding. This will force us to use that binding
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importlib.import_module(f'{mpl_binding}.QtCore')
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mpl_binding_qwidgets = importlib.import_module(f'{mpl_binding}.QtWidgets')
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import matplotlib.backends.backend_qt
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host_qwidgets = importlib.import_module(f'{host_binding}.QtWidgets')
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host_app = host_qwidgets.QApplication(["mpl testing"])
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with pytest.warns(UserWarning, match="Mixing Qt major"):
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matplotlib.backends.backend_qt._create_qApp()
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def test_cross_Qt_imports():
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qt5_bindings = [
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dep for dep in ['PyQt5', 'PySide2']
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if importlib.util.find_spec(dep) is not None
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]
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qt6_bindings = [
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dep for dep in ['PyQt6', 'PySide6']
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if importlib.util.find_spec(dep) is not None
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]
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if len(qt5_bindings) == 0 or len(qt6_bindings) == 0:
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pytest.skip('need both QT6 and QT5 bindings')
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for qt5 in qt5_bindings:
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for qt6 in qt6_bindings:
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for pair in ([qt5, qt6], [qt6, qt5]):
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try:
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_run_helper(__name__, _impl_test_cross_Qt_imports,
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*pair,
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timeout=_test_timeout)
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except subprocess.CalledProcessError as ex:
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# if segfauldt, carry on. We do try to warn the user they
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# are doing something that we do not expect to work
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if ex.returncode == -11:
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continue
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raise
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@pytest.mark.skipif('TF_BUILD' in os.environ,
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reason="this test fails an azure for unknown reasons")
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@pytest.mark.skipif(os.name == "nt", reason="Cannot send SIGINT on Windows.")

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