.. _event_handling-looking_glass: event_handling example code: looking_glass.py ============================================= [`source code `_] :: import numpy as np import matplotlib.pyplot as plt import matplotlib.patches as patches 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) class EventHandler: def __init__(self): fig.canvas.mpl_connect('button_press_event', self.onpress) fig.canvas.mpl_connect('button_release_event', self.onrelease) fig.canvas.mpl_connect('motion_notify_event', self.onmove) self.x0, self.y0 = circ.center self.pressevent = None def onpress(self, event): if event.inaxes!=ax: return if not circ.contains(event)[0]: return self.pressevent = event def onrelease(self, event): self.pressevent = None self.x0, self.y0 = circ.center def onmove(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() Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)