Snap button widget

[fdrgsp]

Creating a new general purpose Snap QPushButton widget linked to the pymmcore-plus snap method.
Once the button is clicked, an image is snapped and the pymmcore-plus imageSnapped signal is emitted.

[fdrgsp]

I wanted to modify the snap method in the main_window like below:

sig.imageSnapped.connect(self._snap)

def _snap(self, img: np.ndarray):
        self.stop_live()
        create_worker(self.update_viewer, img, _start_thread=True)

but when the image is snapped and the ndarray is passed to the update_viewer function I get this error:

WARNING: QObject::connect: Cannot queue arguments of type 'QVector<int>'
(Make sure 'QVector<int>' is registered using qRegisterMetaType().)

Do you know why?

[tlambert03]

Yeah that suggests your communicating with the gui across threads. Updating the napari viewer should never happen in a non main thread. You need to connect the viewer update to a callback after the worker is finished

[ianhi]

Suggested change

	def _snap(self, img: np.ndarray):
	# update in a thread so we don't freeze UI
	create_worker(self.update_viewer, img, _start_thread=True)
	def _snap(self, img: np.ndarray):
	self.stop_live()
	# run snap in a thread so we don't freeze UI
	create_worker(
	self._mmc.snap,
	_start_thread=True,
	)

This can't just update the viewer - it also needs to trigger a new snap so that it works for snap_on_click

[ianhi]

Can probably remove this entirely in the future once the new stage widget comes in

[ianhi]

@fdrgsp this still needs to be changed - currently snap on click is broken

[ianhi]

@fdrgsp can you add some tests - even a super basic one like in https://github.com/tlambert03/napari-micromanager/pull/150?

After that I'm happy to give this a more thorough review

[ianhi]

also, rebasing on main should fix the test failures

[codecov]

Codecov Report

Merging #147 (0024fe0) into main (e411f45) will increase coverage by 0.27%.
The diff coverage is 90.38%.

@@            Coverage Diff             @@
##             main     #147      +/-   ##
==========================================
+ Coverage   81.56%   81.84%   +0.27%     
==========================================
  Files          25       26       +1     
  Lines        2268     2314      +46     
==========================================
+ Hits         1850     1894      +44     
- Misses        418      420       +2     

Impacted Files	Coverage Δ
micromanager_gui/main_window.py	69.56% <50.00%> (+0.12%)	⬆️
...romanager_gui/_core_widgets/_snap_button_widget.py	95.45% <95.45%> (ø)
micromanager_gui/_gui_objects/_tab_widget.py	93.67% <100.00%> (+0.08%)	⬆️

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[fdrgsp]

@fdrgsp can you add some tests - even a super basic one like in #150?

After that I'm happy to give this a more thorough review

@ianhi basic test added!

[ianhi]

Looking good! But still need to fix snap on click.

The only final thing to consider would be to generalize the snap button widget to work for any camera, not just the default camera (e.g. see how #150 and #142 manage this). But this is a good PR otherwise and we can always expand that later.

[ianhi]

@fdrgsp this still needs to be changed - currently snap on click is broken

[fdrgsp]

test error due to codecov/patch — 74.07% of diff hit (target 80.00%)

[ianhi]

One comment on a small improvment - but on the whole this looks good

[ianhi]

@tlambert03 I think this is ready and would be a nice to have as a separate widget for the demo. Any chance of merging this todayish?

[tlambert03]

good stuff. Thanks!