René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: DPI of a figure is doubled after unpickling on M1 Mac","articleBody":"### Bug summary\r\n\r\nWhen a figure is unpickled, it's dpi is doubled. This behaviour happens every time and if done in a loop it can cause an `OverflowError`.\r\n\r\n### Code for reproduction\r\n\r\n```python\r\nimport numpy as np\r\nimport matplotlib\r\nimport matplotlib.pyplot as plt\r\nimport pickle\r\nimport platform\r\n\r\nprint(matplotlib.get_backend())\r\nprint('Matplotlib ver:', matplotlib.__version__)\r\nprint('Platform:', platform.platform())\r\nprint('System:', platform.system())\r\nprint('Release:', platform.release())\r\nprint('Python ver:', platform.python_version())\r\n\r\n\r\ndef dump_load_get_dpi(fig):\r\n    with open('sinus.pickle','wb') as file:\r\n        pickle.dump(fig, file)\r\n\r\n    with open('sinus.pickle', 'rb') as blob:\r\n        fig2 = pickle.load(blob)\r\n    return fig2, fig2.dpi\r\n\r\n\r\ndef run():\r\n    fig = plt.figure()\r\n    x = np.linspace(0,2*np.pi)\r\n    y = np.sin(x)\r\n\r\n    for i in range(32):\r\n        print(f'{i}: {fig.dpi}')\r\n        fig, dpi = dump_load_get_dpi(fig)\r\n\r\n\r\nif __name__ == '__main__':\r\n    run()\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n```\r\nMacOSX\r\nMatplotlib ver: 3.5.2\r\nPlatform: macOS-12.4-arm64-arm-64bit\r\nSystem: Darwin\r\nRelease: 21.5.0\r\nPython ver: 3.9.12\r\n0: 200.0\r\n1: 400.0\r\n2: 800.0\r\n3: 1600.0\r\n4: 3200.0\r\n5: 6400.0\r\n6: 12800.0\r\n7: 25600.0\r\n8: 51200.0\r\n9: 102400.0\r\n10: 204800.0\r\n11: 409600.0\r\n12: 819200.0\r\n13: 1638400.0\r\n14: 3276800.0\r\n15: 6553600.0\r\n16: 13107200.0\r\n17: 26214400.0\r\n18: 52428800.0\r\n19: 104857600.0\r\n20: 209715200.0\r\n21: 419430400.0\r\nTraceback (most recent call last):\r\n  File \"/Users/wsykala/projects/matplotlib/example.py\", line 34, in \u003cmodule\u003e\r\n    run()\r\n  File \"/Users/wsykala/projects/matplotlib/example.py\", line 30, in run\r\n    fig, dpi = dump_load_get_dpi(fig)\r\n  File \"/Users/wsykala/projects/matplotlib/example.py\", line 20, in dump_load_get_dpi\r\n    fig2 = pickle.load(blob)\r\n  File \"/Users/wsykala/miniconda3/envs/playground/lib/python3.9/site-packages/matplotlib/figure.py\", line 2911, in __setstate__\r\n    mgr = plt._backend_mod.new_figure_manager_given_figure(num, self)\r\n  File \"/Users/wsykala/miniconda3/envs/playground/lib/python3.9/site-packages/matplotlib/backend_bases.py\", line 3499, in new_figure_manager_given_figure\r\n    canvas = cls.FigureCanvas(figure)\r\n  File \"/Users/wsykala/miniconda3/envs/playground/lib/python3.9/site-packages/matplotlib/backends/backend_macosx.py\", line 32, in __init__\r\n    _macosx.FigureCanvas.__init__(self, width, height)\r\nOverflowError: signed integer is greater than maximum\r\n```\r\n\r\n### Expected outcome\r\n\r\n```\r\nMacOSX\r\nMatplotlib ver: 3.5.2\r\nPlatform: macOS-12.4-arm64-arm-64bit\r\nSystem: Darwin\r\nRelease: 21.5.0\r\nPython ver: 3.9.12\r\n0: 200.0\r\n1: 200.0\r\n2: 200.0\r\n3: 200.0\r\n4: 200.0\r\n5: 200.0\r\n6: 200.0\r\n7: 200.0\r\n8: 200.0\r\n9: 200.0\r\n10: 200.0\r\n11: 200.0\r\n12: 200.0\r\n13: 200.0\r\n14: 200.0\r\n15: 200.0\r\n16: 200.0\r\n17: 200.0\r\n18: 200.0\r\n19: 200.0\r\n20: 200.0\r\n21: 200.0\r\n22: 200.0\r\n```\r\n\r\n### Additional information\r\n\r\nThis seems to happen only on M1 MacBooks and the version of python doesn't matter.\r\n\r\n### Operating system\r\n\r\nOS/X\r\n\r\n### Matplotlib Version\r\n\r\n3.5.2\r\n\r\n### Matplotlib Backend\r\n\r\nMacOSX\r\n\r\n### Python version\r\n\r\n3.9.12\r\n\r\n### Jupyter version\r\n\r\n_No response_\r\n\r\n### Installation\r\n\r\npip","author":{"url":"https://github.com/wsykala","@type":"Person","name":"wsykala"},"datePublished":"2022-07-22T15:05:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/23471/matplotlib/issues/23471"}