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[Bug]: pick events do not forward mouseevent-key on Linux #24199

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#24250
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[Bug]: pick events do not forward mouseevent-key on Linux#24199
#24250
Labels
status: confirmed bug
Milestone
v3.6.2

Description

@raphaelquast
raphaelquast
opened on Oct 17, 2022

Bug summary

Somehow on CentOS Linux 7 keyboard-buttons are not forwarded with pick_events... on Windows 10 everything works as expected.

Code for reproduction

import matplotlib.pyplot as plt

f, ax = plt.subplots()
s = ax.scatter([1,2,3,4], [1,2,3,4], s=1000)
s.set_picker(True)

def doit(event):
    if event.name == "button_press_event":
        print(event.name, event.key)
    if event.name == "pick_event":
        print(event.name, event.mouseevent.key)

f.canvas.mpl_connect("button_press_event", doit)
f.canvas.mpl_connect("pick_event", doit)

Actual outcome

When clicking on one of the datapoints while pressing the buttons 1 2 and 3 the following happens:

on Windows I get:

pick_event 1
button_press_event 1
pick_event 2
button_press_event 2
pick_event 3
button_press_event 3

on CentOS Linux I get:

pick_event None
button_press_event 1
pick_event None
button_press_event 2
pick_event None
button_press_event 3

Expected outcome

The same output for both OS

Operating system

Windows / Linux CentOS7

Matplotlib Version

3.6.1

Matplotlib Backend

Qt5Agg

Python version

3.9.13

Installation

conda

Activity

  1. oscargus commented on Oct 18, 2022

    @oscargus
    oscargus
    on Oct 18, 2022
    Member

    (As I have some issues with my Qt install, I tried it with tk and wx and get None for both types of events... Also on CentOS 7.)

  2. raphaelquast commented on Oct 18, 2022

    @raphaelquast
    raphaelquast
    on Oct 18, 2022
    ContributorAuthor

    @oscargus
    Thanks for the response! That's even worse 😅 Do you have any idea what's going on here?
    (as far as I know this is the correct way of determining if a key is pressed while a mouse-button is clicked...)

  3. oscargus commented on Oct 18, 2022

    @oscargus
    oscargus
    on Oct 18, 2022
    Member

    Oh, I wouldn't trust my statement so much...

    Ler me fet back tomorrow (left the office now) with the proper outcome.

    No, I do not really know what is going on, but I seem to recall that there is something with Wayland not reporting keys correctly. Will try to dig up that issue.

  6. tacaswell commented on Oct 20, 2022

    @tacaswell
    tacaswell
    on Oct 20, 2022
    Member

    @oscargus It took me a while to sort out, you have to hold down '1" (or really any key) as this is looking at the key board key not the mouse button). I was also thrown using 1, 2, 3 as those are the names of the mouse buttons. If I hold 'a' down I get

    pick_event None
button_press_event a
pick_event None
button_press_event a

    which matches the OP.

    This a regression from 3.5, likely due to the refactoring of the event tracking done in #16931 but have not bisected to be sure.

    attn @anntzer

  7. tacaswell
    added this to the v3.6.2 milestone on Oct 20, 2022
  8. tacaswell
    added
    status: confirmed bug
    on Oct 20, 2022

  9. anntzer commented on Oct 20, 2022

    @anntzer
    anntzer
    on Oct 20, 2022
    Contributor

    Indeed, this occurs because both (1) attaching the key attribute to the mouseevent and (2) emitting the pick_event are now done by callbacks, and we just need to ensure that callback (1) comes before callback (2), i.e.

    diff --git i/lib/matplotlib/figure.py w/lib/matplotlib/figure.py
index 1636e20101..2bbd5254b9 100644
--- i/lib/matplotlib/figure.py
+++ w/lib/matplotlib/figure.py
@@ -2444,10 +2444,6 @@ class Figure(FigureBase):
         # pickling.
         self._canvas_callbacks = cbook.CallbackRegistry(
             signals=FigureCanvasBase.events)
-        self._button_pick_id = self._canvas_callbacks._connect_picklable(
-            'button_press_event', self.pick)
-        self._scroll_pick_id = self._canvas_callbacks._connect_picklable(
-            'scroll_event', self.pick)
         connect = self._canvas_callbacks._connect_picklable
         self._mouse_key_ids = [
             connect('key_press_event', backend_bases._key_handler),
@@ -2458,6 +2454,10 @@ class Figure(FigureBase):
             connect('scroll_event', backend_bases._mouse_handler),
             connect('motion_notify_event', backend_bases._mouse_handler),
         ]
+        self._button_pick_id = self._canvas_callbacks._connect_picklable(
+            'button_press_event', self.pick)
+        self._scroll_pick_id = self._canvas_callbacks._connect_picklable(
+            'scroll_event', self.pick)
 
         if figsize is None:
             figsize = mpl.rcParams['figure.figsize']

    fixes the issue AFAICT.

    Feel free to pick up the patch, or I'll make a PR if no one else does.

  10. QuLogic
    added a commit that references this issue on Oct 22, 2022

    Fix key reporting in pick events

    9b34b25
  11. timhoffm
    closed this as completedin #24250on Oct 22, 2022

  12. raphaelquast commented on Oct 23, 2022

    @raphaelquast
    raphaelquast
    on Oct 23, 2022
    ContributorAuthor

    awesome! thanks for fixing this!!

  13. melissawm
    added a commit that references this issue on Dec 19, 2022

    Fix key reporting in pick events

    3862b87
  14. imgbot
    added a commit that references this issue on Apr 19, 2026

    Fix key reporting in pick events

    c22a025
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