.. only:: html .. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_event_handling_looking_glass.py: ============= Looking Glass ============= Example using mouse events to simulate a looking glass for inspecting data. .. image:: /gallery/event_handling/images/sphx_glr_looking_glass_001.png :alt: Left click and drag to move looking glass :class: sphx-glr-single-img .. code-block:: default import numpy as np import matplotlib.pyplot as plt import matplotlib.patches as patches # Fixing random state for reproducibility np.random.seed(19680801) x, y = np.random.rand(2, 200) fig, ax = plt.subplots() circ = patches.Circle((0.5, 0.5), 0.25, alpha=0.8, fc='yellow') ax.add_patch(circ) ax.plot(x, y, alpha=0.2) line, = ax.plot(x, y, alpha=1.0, clip_path=circ) ax.set_title("Left click and drag to move looking glass") class EventHandler: def __init__(self): fig.canvas.mpl_connect('button_press_event', self.on_press) fig.canvas.mpl_connect('button_release_event', self.on_release) fig.canvas.mpl_connect('motion_notify_event', self.on_move) self.x0, self.y0 = circ.center self.pressevent = None def on_press(self, event): if event.inaxes != ax: return if not circ.contains(event)[0]: return self.pressevent = event def on_release(self, event): self.pressevent = None self.x0, self.y0 = circ.center def on_move(self, event): if self.pressevent is None or event.inaxes != self.pressevent.inaxes: return dx = event.xdata - self.pressevent.xdata dy = event.ydata - self.pressevent.ydata circ.center = self.x0 + dx, self.y0 + dy line.set_clip_path(circ) fig.canvas.draw() handler = EventHandler() plt.show() .. _sphx_glr_download_gallery_event_handling_looking_glass.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: looking_glass.py ` .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: looking_glass.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_