feat: add toolbar widget

[tlambert03]

closes #593

this PR includes #598, and should wait for it to merge

[codecov]

Codecov Report

Attention: 34 lines in your changes are missing coverage. Please review.

Comparison is base (2fa477d) 87.98% compared to head (7f39313) 87.56%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #597      +/-   ##
==========================================
- Coverage   87.98%   87.56%   -0.42%     
==========================================
  Files          39       40       +1     
  Lines        4609     4727     +118     
==========================================
+ Hits         4055     4139      +84     
- Misses        554      588      +34     

Files	Coverage Δ
src/magicgui/backends/_ipynb/__init__.py	100.00% <ø> (ø)
src/magicgui/backends/_qtpy/__init__.py	100.00% <ø> (ø)
src/magicgui/widgets/__init__.py	100.00% <ø> (ø)
src/magicgui/widgets/_concrete.py	89.45% <100.00%> (+0.04%)	⬆️
src/magicgui/widgets/bases/__init__.py	100.00% <100.00%> (ø)
src/magicgui/widgets/protocols.py	100.00% <100.00%> (ø)
src/magicgui/widgets/bases/_toolbar.py	96.00% <96.00%> (ø)
src/magicgui/backends/_qtpy/widgets.py	87.43% <78.37%> (-0.38%)	⬇️
src/magicgui/backends/_ipynb/widgets.py	61.34% <34.21%> (-4.23%)	⬇️

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[tlambert03]

this is mostly working now for both backends... but doesn't yet have icon support. I might want to add icons in a new PR. superqt recently got support for iconify ... and it would nice to be able to provide the same flexibility for ipywidgets.

[tlambert03]

@larsoner, i know you haven't dug too deeply into how things are structured here, but if you have a moment to look at the general protocol, and backend implementations here (ipynb, qt), I'd welcome your input.

I implemented a toolbar as a top level widget (magicgui.widgets.Toolbar()) rather than a method on something like main window or layout. So it would be used by adding/inserting a Toolbar() into a widgets.Container

still need to write tests, and as mentioned above, still contemplating how to add icons (see related #598)

[larsoner]

So far so good! To get a "native feel" I have generically:

toolbar = widgets.ToolBar()
noop = lambda *args, **kwargs: None
toolbar.add_button("Play", icon="play", callback=noop)
toolbar.add_button("Pause", icon="pause", callback=noop)
toolbar.add_button("Screenshot", icon="camera", callback=noop)
toolbar.add_button("Movie", icon="film", callback=noop)

then in my Qt half doing:

    window = widgets.MainWindow(widgets=columns, layout="horizontal", labels=False)
    window.native.addToolBar(toolbar.native)

and in the NB half doing:

    from ipywidgets import AppLayout
    window = AppLayout(
        header=toolbar.native,
        left_sidebar=columns[0].native,
        center=columns[1].native,
        pane_heights=['30px', 5, 1]
    )

plus the rest of the stuff from mne-tools/mne-python#11990 I get a decent result (other than Qt icons as expected) except for I think the toolbar button text being wrong on Qt?:

NB	Qt

[tlambert03]

thanks!

except for I think the toolbar button text being wrong on Qt?

ah yep, that's related to icons being unfinished. will fix

question for you regarding API:
I'm inclined to add an explicit MainWindow.add_toolbar(tb: widgets.ToolBar) method to take full advantage of QMainWindow.addToolBar. Do you prefer that to a magic alternative where we call that under the hood in the qt backend if a ToolBar is in the list of the widgets? (or perhaps just the first item in the list)?

[larsoner]

I think the explicit one is better and what I would expect.

[tlambert03]

i'm going to merge this and continue work in #604