figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812. by lkjell · Pull Request #9814 · matplotlib/matplotlib · GitHub

PR Summary

In the documentation 1 figure_enter_event uses LocationEvent. However, previously it just uses the base class Event. This cause some problem when trying to access LocationEvent attributes because they did not exist. This addresses issue #9812.

Fix also an issue that tkagg backend does not have a figure_enter_event.
gtk3, Qt5 and wx pass in coordinates when entering figure.

The tkagg backend did not have a figure_leave_event. Enabling that as well.

Sample script using Qt5 backend. Move the cursor in and out of the figure.

import matplotlib

matplotlib.use("Qt5Agg")
import matplotlib.pyplot as plt
import numpy as np

x = range(100)

fig, ax = plt.subplots()
ax.plot(np.random.rand(10))


def stat(event):
    print("axes: {}, x: {}, y: {}".format(event.inaxes, event.x, event.y))


cid = fig.canvas.mpl_connect('figure_enter_event', stat)
cid = fig.canvas.mpl_connect('figure_leave_event', stat)

plt.show()

PR Checklist

Code is PEP 8 compliant

Should perhaps change the backends to pass inn their coordinates as well. As for now the fix is having

else:
    x = None
    y = None

in FigureCanvasBase.enter_notify_event, as in the commit.

grep "FigureCanvasBase.enter_notify_event" *py
backend_gtk3.py:        FigureCanvasBase.enter_notify_event(self, event)
backend_gtk.py:        FigureCanvasBase.enter_notify_event(self, event, xy=(x, y))
backend_qt5.py:        FigureCanvasBase.enter_notify_event(self, guiEvent=event)
backend_wx.py:        FigureCanvasBase.enter_notify_event(self, guiEvent=evt)

Thanks for the PR. You'll probably get more testers if you give us a sample script to try that shows this works better.

wow, that is a pretty big likely long standing bug!

ok, so it looks like the sub-classes of FigureCanvasBase that over-ride enter_notify_event are changing the signature / purpose a bit (gtk, gtk3, tk). The method on FigureCanvasBase generates the Event instance that Matplotlib uses internally and turns the crank on our callbacks where as the methods of the sub-classes are registered as callbacks into the underlying GUI event handling frame work which has it's own required signature (if you look at the Qt5, Wx and Webagg backends they use a differently method to register into the GUI framework callback system).

Doing this from scratch I think the second pattern is better, but it is probably not worth the effort to deprecate and rename the bridge methods in {gtk,gtk3, tk} (the work would be to create new methods rename the methods to _on_enter, shim the behavior back into enter_notify_event and warn about usage. In a future release we would remove the methods on the sub-classes and just let it fallback to the base class behavior).

The method name enter_notify_event (gtk, gtk3, tk) I believe was the initial usage. After a while when changing the signature of the FigureCanvasBase.enter_notify_event to use add xy coordinates or LocationEvent something must have been missed out.

The bridge method for tk enter_notify_event I added in commit cb3146d was for consistency of the naming scheme used in the class.

Some minor comments, but 👍 as-is

Tested on

qt5
tk

This can just be self.enter_notif_event(guiEvent=event, xy=(x, y))

Could do but that would break some inconsistency with the other event as well. For example

def wheelEvent(self, event):
    x, y = self.mouseEventCoords(event)
    # from QWheelEvent::delta doc
    if event.pixelDelta().x() == 0 and event.pixelDelta().y() == 0:
        steps = event.angleDelta().y() / 120
    else:
        steps = event.pixelDelta().y()
    if steps:
        FigureCanvasBase.scroll_event(self, x, y, steps, guiEvent=event)

def keyPressEvent(self, event):
    key = self._get_key(event)
    if key is not None:
        FigureCanvasBase.key_press_event(self, key, guiEvent=event)

def keyReleaseEvent(self, event):
    key = self._get_key(event)
    if key is not None:
        FigureCanvasBase.key_release_event(self, key, guiEvent=event)

Fair. I suppose those could also all be changed to normal method calls, but that is beyond the scope of this PR.

Can you add a warning here like

warnings.warn('enter_notify_event expects a location but your backend did not pass one. '
              'This may become mandatory in the future', stacklevel=2)

?

cbook.warn_deprecated?

This can also just be self.enter_notify_event.

This is probably better named something else (as it is new)

Could but breaks naming scheme used in the class.

@tacaswell Will this get merged soon or there need more testing?

This one has gone too long @tacaswell . I needed to strip some commits since there where some confilics with the master branch and I simple do not have the time to solve the merge conflics.

@lkjell Sorry this has sat for so long, I assure you it is not personal!

I am confused by your comment though as it looks like have fixed the merge conflicts (as the tests are running).

Can this be changed to '3.0' ?

Can you also add an entry in https://github.com/matplotlib/matplotlib/tree/master/doc/users/next_whats_new (so people know they can use this!)

This is a bug fix. https://matplotlib.org/users/event_handling.html
I added some fixes such that backends passed in their coordinates as well. Apparently not all passed in their coordinates.

🐑 your right, that is what I get for reading from the bottom!

If I understand correctly, the original PR included fixes to backends; the present version of this PR adds a warning, but does not have any fixes to the backends. Therefore, if this PR is merged, an attempt to use the figure enter/leave events will generate the deprecation warnings until another PR provides the backend fixes. It is unfortunate that those original fixes were wiped out because they needed to be rebased. Am I correct, or hopelessly confused?
It would be nice to get all this straightened out ASAP.

@efiring something like that. If memory serve right some backend did pass in None, None. Some did not register an Enter event(gtk).

The backend fix had merge confict and you need to edit the super to python3 only.

This is now consistent with the documentation: https://matplotlib.org/users/event_handling.html

My fault for not looking into deeper. I restored the non-conflicting commits. The only conflicting backend is tk. It appears that file was renamed to _backend_tk.py

lkjell changed the title figure_enter_event uses now LocationEvent instead of Event. figure_enter_event uses now LocationEvent instead of Event. Fix issue #8576. Nov 19, 2017

lkjell changed the title figure_enter_event uses now LocationEvent instead of Event. Fix issue #8576. figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812. Nov 19, 2017

lkjell closed this Nov 19, 2017

lkjell reopened this Nov 19, 2017

tacaswell added this to the v2.2 milestone Nov 19, 2017

tacaswell approved these changes Nov 19, 2017

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tacaswell reviewed Nov 19, 2017

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tacaswell added GUI: gtk GUI: nbagg GUI: MacOSX GUI: Qt GUI: tk GUI: webagg GUI: wx labels Nov 20, 2017

tacaswell modified the milestones: needs sorting, v3.0 Mar 2, 2018

tacaswell reviewed Mar 2, 2018

View reviewed changes

lkjell added 3 commits March 4, 2018 22:54

figure_enter_event uses now LocationEvent instead of Event.

8cff894

This is now consistent with the documentation: https://matplotlib.org/users/event_handling.html

backend gtk3, qt5/qt4 and wx pass in coordinates when entering figure.

ce76875

bump warnings

3fdd527

Enable enter/leave notify for tk

64e37bc

efiring approved these changes Mar 5, 2018

View reviewed changes

efiring merged commit 4f5715a into matplotlib:master Mar 5, 2018

efiring mentioned this pull request Mar 5, 2018

figure_enter_event generates base Event and not LocationEvent #9812

Closed

lkjell deleted the fix_figure_enter_event branch March 5, 2018 04:46

anntzer mentioned this pull request Jul 9, 2018

AttributeError: 'QEvent' object has no attribute 'pos' #11607

Closed

anntzer mentioned this pull request Mar 27, 2020

Make it easier to improve UI event metadata. #16931

Merged

6 tasks

                   def enterEvent(self, event):
-                      FigureCanvasBase.enter_notify_event(self, guiEvent=event)
+                      x, y = self.mouseEventCoords(event.pos())
+                      FigureCanvasBase.enter_notify_event(self, guiEvent=event, xy=(x, y))

                       if xy is not None:
                           x, y = xy
                           self._lastx, self._lasty = x, y
+                      else:

+                      x = evt.GetX()
+                      y = self.figure.bbox.height - evt.GetY()
+                      evt.Skip()
+                      FigureCanvasBase.enter_notify_event(self, guiEvent=evt, xy=(x, y))

                       y = self.figure.bbox.height - event.y
                       FigureCanvasBase.motion_notify_event(self, x, y, guiEvent=event)
+                  def enter_notify_event(self, event):

figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812. by lkjell · Pull Request #9814 · matplotlib/matplotlib · GitHub

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figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812. - #9814

figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812.#9814efiring merged 4 commits intomatplotlib:mastermatplotlib/matplotlib:masterfrom lkjell:fix_figure_enter_eventCopy head branch name to clipboard

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figure_enter_event uses now LocationEvent instead of Event. Fix issue #9812.#9814
efiring merged 4 commits into
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lkjell:fix_figure_enter_event

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tacaswell commented Nov 19, 2017 •
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