René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: .contains for some artists does not check for visibility","articleBody":"### Bug summary\n\nI recently managed to find the source of a long-standing bug in my application that was quite tricky to find.\r\n\r\nIt turned out to be a consequence of the `contains` method of a line returning `true` even when the line was set to not visible at the time. Although from what I can see in the documentation there is nothing prohibiting this, I think almost everyone would want `contains` to return false for objects which have been plotted and set to invisible.\r\n\r\nMoreover, a non-exhaustive look through the code shows that there are class-specific checks in place for visibility for some objects, but not others. Specifically, the following do not have checks:\r\n\r\n```\r\nlines.Line2D\r\npatches.Patch\r\nquiver.QuiverKey\r\n```\r\n\r\nBut these ones do (though not explicitly documented.)\r\n\r\n```\r\ncollections.Collection\r\ntext.Text\r\nimage.BboxImage\r\n```\r\n\r\nIt seems like a fix might put the check for visibility in the `_default_contains` method of `Artist`. This is called by the child implementations, but as of now seems to provide only a bail-out if the event is outside the figure canvas. Although I guess maybe it was done that way if there are some specific exceptions where you would actually want `contains` to return true (maybe bounding boxes or more abstract things not plotted directly).\n\n### Code for reproduction\n\n```python\nfrom matplotlib import pyplot as plt\r\n\r\nclass Demo:\r\n\r\n    def __init__(self):\r\n\r\n        fig, ax = plt.subplots()\r\n\r\n        self.lines = []\r\n        self.lines.append(ax.axhline(1))\r\n        self.lines.append(ax.axhline(-1))\r\n        self.lines[0].set_visible(False)\r\n\r\n        self.vis_points = ax.scatter([-0.5, 0.5], [0, 0])\r\n        self.invis_points = ax.scatter([0], [0])\r\n        self.invis_points.set_visible(False)\r\n        self.points = [self.vis_points, self.invis_points]\r\n\r\n        fig.canvas.mpl_connect('button_press_event', self.clicked)\r\n\r\n        plt.show()\r\n\r\n    def clicked(self, event):\r\n        at_obj = lambda x: x.contains(event)[0]\r\n\r\n        if any(at_obj(l) for l in self.lines):\r\n            print(f\"Clicked on a line at {event.ydata:0.3f}\")\r\n        elif any(at_obj(p) for p in self.points):\r\n            print(f\"Clicked point at {event.ydata:0.3f}\")\r\n        else:\r\n            print('Clicked elsewhere')\r\n\r\nif __name__ == '__main__':\r\n    demo = Demo()\n```\n\n\n### Actual outcome\n\nIt is possible to click anywhere near the invisible line at y=1 and see click registered message.\r\nHowever, clicking at [0,0], the location of an invisible scatter point does not show a point clicked message (expected behavior).\n\n### Expected outcome\n\nClicking anywhere y=1 should not generate a line click message --- just as clicking at 0,0 does not generate a point clicked message.\n\n### Additional information\n\n_No response_\n\n### Operating system\n\nArch linux, Linux mint, Windows\n\n### Matplotlib Version\n\n3.5.0\n\n### Matplotlib Backend\n\nqt\n\n### Python version\n\n3.9.9\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\n_No response_","author":{"url":"https://github.com/rdgraham","@type":"Person","name":"rdgraham"},"datePublished":"2022-09-11T22:04:10.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/23875/matplotlib/issues/23875"}