plot_event2.py

import numpy as np
import matplotlib.pyplot as plt


class DraggableRectangle:
    def __init__(self, rect):
        self.rect = rect
        self.press = None

    def connect(self):
        """Connect to all the events we need."""
        self.cidpress = self.rect.figure.canvas.mpl_connect(
            'button_press_event', self.on_press)
        self.cidrelease = self.rect.figure.canvas.mpl_connect(
            'button_release_event', self.on_release)
        self.cidmotion = self.rect.figure.canvas.mpl_connect(
            'motion_notify_event', self.on_motion)

    def on_press(self, event):
        """Check whether mouse is over us; if so, store some data."""
        if event.inaxes != self.rect.axes:
            return
        contains, attrd = self.rect.contains(event)
        if not contains:
            return
        print('event contains', self.rect.xy)
        self.press = self.rect.xy, (event.xdata, event.ydata)

    def on_motion(self, event):
        """Move the rectangle if the mouse is over us."""
        if self.press is None or event.inaxes != self.rect.axes:
            return
        (x0, y0), (xpress, ypress) = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress
        # print(f'x0={x0}, xpress={xpress}, event.xdata={event.xdata}, '
        #       f'dx={dx}, x0+dx={x0+dx}')
        self.rect.set_x(x0 + dx)
        self.rect.set_y(y0 + dy)

        self.rect.figure.canvas.draw()

    def on_release(self, event):
        """Clear button press information."""
        self.press = None
        self.rect.figure.canvas.draw()

    def disconnect(self):
        """Disconnect all callbacks."""
        self.rect.figure.canvas.mpl_disconnect(self.cidpress)
        self.rect.figure.canvas.mpl_disconnect(self.cidrelease)
        self.rect.figure.canvas.mpl_disconnect(self.cidmotion)


fig, ax = plt.subplots()
rects = ax.bar(range(10), 20 * np.random.rand(10))
drs = []
for rect in rects:
    dr = DraggableRectangle(rect)
    dr.connect()
    drs.append(dr)

plt.show()