MNT: Add modifier key press handling to macosx backend #21512

greglucas · 2021-10-31T14:51:53Z

PR Summary

The flagsChanged event handles single presses of modifier keys, so we need to send the corresponding string to our key press handlers from within that routine. Modifier + second key is handled within the KeyUp/KeyDown routines already, so leave those alone.

Taking the example from issue #20486

import matplotlib.pyplot as plt
fig = plt.figure()

def on_key(event):
    print('you pressed', event.key, event.xdata, event.ydata)
def on_key_release(event):
    print('you released', event.key, event.xdata, event.ydata)

fig.canvas.mpl_connect('key_press_event', on_key)
fig.canvas.mpl_connect('key_release_event', on_key_release)
plt.show()

this adds the single modifier key presses back in. Before this, the (modifier + key) "cmd+a" would show up, but there wasn't a single "cmd" (modifier) preceding it.

you pressed cmd None None
you pressed cmd+a None None

I'm not sure how to send key press events through the terminal natively, so there are no automated tests.

closes #20486
closes #9837

PR Checklist

Has pytest style unit tests (and pytest passes).
Is Flake 8 compliant (run flake8 on changed files to check).
New features are documented, with examples if plot related.
Documentation is sphinx and numpydoc compliant (the docs should build without error).
Conforms to Matplotlib style conventions (install flake8-docstrings and run flake8 --docstring-convention=all).
New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).

jklymak

This works as advertised. Not an expert on macOS backend, so not sure this is the "right" fix, but....

anntzer · 2021-11-20T10:54:28Z

src/_macosx.m

-   match up with what the front-end and does the front-end even handle modifier keys by themselves?
-
+// flagsChanged gets called on single modifier keypresses
+// The modifier + second key gets handled in convertKeyEvent in KeyUp/KeyDown


does it also work for e.g. "ctrl+shift"? (dunno, just asking)

a ctrl, shift, f for example produces this:

you pressed cmd None None you pressed shift None None you pressed cmd+F None None you pressed cmd None None

I think the extra command at the end is there due to the shift also being let up and changing state while command is still pressed...

On other backends, the second press is "cmd+shift", not just shift. (Well, ctrl+shift on non-osx.)

OK, so this was more complicated than I had hoped... The flagsChanged gets called on any press OR release, which is why I was printing out "pressed" when it was really a "release".

I think this means we have to keep track of the state of the keys ourselves and what is going up/down. I think this now matches what other backends do, including press/release properly.

src/_macosx.m

anntzer · 2021-11-21T11:46:22Z

src/_macosx.m

+        lastCommand = false;
+        keyChangeCommand = true;
+        keyrelease = true;
+    }


Not a huge deal, but I guess each of these pairs can be grouped to

bool isPress = true; // false for release if ([event modifierFlags] & NSEventModifierFlagCommand) { lastCommand = !lastCommand keyChangeCommand = true isPress = lastCommand; } else if (...) ... } else { // Unknown flag return; }

NSEventModifierFlagCommand will only be true when it is held down, so we would miss the release with that implementation I think... We could probably squash the two cases into a single if block with your suggestion, but maybe I'm missing a more elegant way to keep track of the push/release here:

if ((([event modifierFlags] & NSEventModifierFlagCommand) && !lastCommand) || (!([event modifierFlags] & NSEventModifierFlagCommand) && lastCommand)) { // Command pressed or released lastCommand = !lastCommand; keyChangeCommand = true; keypress = lastCommand; } ...

Ah, sorry, I missed the inversion. Perhaps a good place for a ^ (xor)?

👍 Yep, a good place for it, thanks.

LGTM, although probably another mac user should test :-)

anntzer · 2021-11-26T00:12:29Z

Ah, perhaps also update the table at https://github.com/matplotlib/matplotlib/blob/main/doc/users/explain/event_handling.rst#event-connections (under "note")?

greglucas · 2021-11-26T03:35:29Z

Good suggestion about updating the table.

The shift + 2 on US keyboards is @, so I'm not sure whether the " for the other backends are expected or not.
I don't have an altGr key, so I can't check that.
I don't have a capital A key, I'm not entirely clear what that entry is referring to? Possibly pressing a with caps_lock on...

anntzer · 2021-11-26T10:01:52Z

The shift + 2 on US keyboards is @, so I'm not sure whether the " for the other backends are expected or not.

Looks like the original author was from Mexico where shift+2 is " (http://kbdlayout.info/KBDLA/), probably the entry should be fixed for qwerty.

I don't have an altGr key, so I can't check that.

Per https://en.wikipedia.org/wiki/AltGr_key I guess that's "left alt/option"

I don't have a capital A key, I'm not entirely clear what that entry is referring to? Possibly pressing a with caps_lock on...

I guess no one has, probably that was capslocked indeed?

anntzer · 2021-11-27T17:39:02Z

Thanks for the table update. I'll merge in a day or two if the macos crew doesn't manifest themselves for a second review :)

jklymak · 2021-11-27T18:41:50Z

I've not been following. Has it diverged significantly from when I reviewed? I can try it again.

anntzer · 2021-11-27T18:45:46Z

Mostly just check that things work just as advertised in the table under event_handling.rst.

anntzer

modulo @jklymak checking, per the above.

greglucas · 2021-11-27T19:32:49Z

There was quite a bit of logic rework since your initial review, and this now handles modifier key_release events too. Mostly just mash some keys and make sure you get back what you're expecting when testing with the script included in the example. If you have an AltGr key, it would be good to update the table entry for that too, as I can't check that.

jklymak · 2021-11-27T20:30:04Z

I've never heard of an AltGr key so I guess if don't have one. I'll try and check tomorrow

dstansby

Works well for me, and fixes issues as advertised. I haven't reviewed the code in _macosx.m, but the doc update looks good.

dstansby · 2021-11-28T13:23:07Z

Oh, and I don't think macs have AltGr keys, so leaving that empty is fine.

The flagsChanged event handles single presses of modifier keys, so we need to send the corresponding string to our key press handlers from within that routine. Modifier + second key is handled within the KeyUp/KeyDown routines already, so leave those alone.

Handle the key-press and release events on macosx.

This removes half of the else-if blocks and combines the keypress/keyrelease for each key into a single statement with negation for whether it was a press or release being handled.

- This updates the if conditional to use XOR logic instead of the two negated and/or conditions. - It also handles the shift modifier when combined with other modifier keys, as before (ctrl + shift + cmd) would have not printed out the middle shift.

greglucas · 2021-11-30T23:42:39Z

I am going to self-merge this based on the 3 approvals and to avoid future rebases. It is a bugfix, but it has been broken for a while, so I don't think we should worry about backporting this.

greglucas added OS: Apple GUI: MacOSX PR: bugfix Pull requests that fix identified bugs labels Oct 31, 2021

greglucas added this to the v3.6.0 milestone Oct 31, 2021

jklymak approved these changes Nov 8, 2021

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greglucas requested a review from dstansby November 18, 2021 14:59

anntzer reviewed Nov 20, 2021

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greglucas force-pushed the macosx-keypress branch 2 times, most recently from fc77052 to 2120ca0 Compare November 20, 2021 14:40

anntzer reviewed Nov 21, 2021

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greglucas force-pushed the macosx-keypress branch from 5a67505 to 434dd36 Compare November 22, 2021 18:46

greglucas force-pushed the macosx-keypress branch from a14bf27 to 106d6bc Compare November 26, 2021 03:30

greglucas force-pushed the macosx-keypress branch from 106d6bc to 9d98853 Compare November 26, 2021 15:04

anntzer reviewed Nov 27, 2021

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anntzer approved these changes Nov 27, 2021

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dstansby approved these changes Nov 28, 2021

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greglucas and others added 4 commits November 30, 2021 07:49

FIX: macosx key-press key-release events

97c99c2

Handle the key-press and release events on macosx.

MNT: Cleanup the logic in macosx keypress handling

f00a204

This removes half of the else-if blocks and combines the keypress/keyrelease for each key into a single statement with negation for whether it was a press or release being handled.

DOC: Add macosx keypress events to the documentation

7819b0e

greglucas force-pushed the macosx-keypress branch from 9d98853 to 7819b0e Compare November 30, 2021 14:59

greglucas merged commit 4569a70 into matplotlib:main Nov 30, 2021

greglucas deleted the macosx-keypress branch November 30, 2021 23:43

QuLogic mentioned this pull request Sep 9, 2022

Consolidate release notes for 3.6 #23814

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MNT: Add modifier key press handling to macosx backend #21512

MNT: Add modifier key press handling to macosx backend #21512

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MNT: Add modifier key press handling to macosx backend #21512

MNT: Add modifier key press handling to macosx backend #21512

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