BUG: RectangleSelector modifies view

[larsoner]

Bug report

Bug summary

RectangleSelector:

1. Modifies dataLim
2. This modification seemingly cannot be reverted by removing the patch, or by modifying the patch properties

Basically I want to be able to use RectangleSelector without it modifying ax.dataLim, because if it does it messes up autoscale.

Code for reproduction

import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
from matplotlib.widgets import RectangleSelector

fig, ax = plt.subplots()
lim = ax.dataLim
ax.plot([-0.1, 0.1], [-0.1, 0.1])
assert lim.x0 == lim.y0 == -0.1
assert lim.width == lim.height == 0.2
for kind in ('rect', 'rs'):
    if kind == 'rect':
        rect = Rectangle((0, 0), 0, 1)
        ax.add_patch(rect)
    else:
        rs = RectangleSelector(ax, lambda x: None)
        rect = rs.to_draw
    assert isinstance(rect, Rectangle)
    ax.relim()
    assert lim.x0 == lim.y0 == -0.1
    assert lim.width == 0.2
    assert lim.height == 1.1
    ax.patches.remove(rect)
    assert ax.patches == []
    ax.relim()
    assert lim.height == 0.2, (kind, lim.height)

The plain "Rectangle" version passes, but the "RectangleSelector" version does not:

    assert lim.height == 0.2, (kind, lim.height)
AssertionError: ('rs', 1.1)

And the resulting plot is "stuck" with a minimum autolim y max of 1. I also tried setting properties of the Rectangle patch that's part of the RectangleSelector (xy, width, height) and calling ax.relim() but the bound of 1. never decreases.

Matplotlib version

• Operating system: Linux x86_64
• Matplotlib version: latest master
• Matplotlib backend: Qt5Agg
• Python version: 3.8

[QuLogic]

ax.patches.remove(rect)

Not going to fix anything, but you should use rect.remove() instead of touching ax.patches.

[PrateekArya]

I am facing the same issue. This seems to be same as #19067.

[dstansby]

I'm a bit confused as to what's going on here - is the desired behaviour that adding a RectangleSelector to an Axes doesn't modify the Axes limits?

[larsoner]

It has been a while since I thought about this, but yes I think so. Rectangle behaves this way but RectangleSelector does not, it seems.