hv.render ignores theme bgcolor

[AlonKellner]

Version Info

Colab versions

On the latest Colab (released on 2024-07-22) with Google Chrome (127.0.6533.74) after updating pip versions:

>>> pip install -qU jupyter_bokeh panel holoviews bokeh

These are the relevant pip versions to reproduce this:

>>> pip freeze | grep -e holoviews -e bokeh -e panel -e numpy
bokeh==3.4.3
holoviews==1.19.1
jupyter_bokeh==4.0.5
numpy==1.26.4
panel==1.4.5

VSCode versions

On VSCode:

Version: 1.92.0 (user setup)
Commit: b1c0a14de1414fcdaa400695b4db1c0799bc3124
Date: 2024-07-31T23:26:45.634Z
Electron: 30.1.2
ElectronBuildId: 9870757
Chromium: 124.0.6367.243
Node.js: 20.14.0
V8: 12.4.254.20-electron.0
OS: Windows_NT x64 10.0.26257

with devcontainers, based on the python devcontainer image:
mcr.microsoft.com/devcontainers/python:1-3.10-bookworm
with the full devcontainer configureation in here.
after updating pip versions:

>>> pip install -qU jupyter_bokeh panel holoviews bokeh

These are the relevant pip versions to reproduce this:

>>> pip freeze | grep -e holoviews -e bokeh -e panel -e numpy
bokeh==3.4.3
holoviews==1.19.1
jupyter_bokeh==4.0.5
numpy==2.0.1
panel==1.4.5

Behavior

Expected

In all cases when hv.renderer('bokeh').theme = 'dark_minimal' is used, the theme should be applied correctly.

Observed

In some cases when hv.renderer('bokeh').theme = 'dark_minimal' is used, the theme bgcolor is not applied correctly.

Here is a table listing all cases, where ✅ means it's fine, and ❌ means the bgcolor is not applied correctly:

	Colab	VSCode
hv.Image	✅	✅
bk.plotting.show(hv.render(hv.Image))	❌	❌
pn.Row(hv.Image)	✅	❌
pn.Row(hv.render(hv.Image))	❌	❌
pn.Row(hv.Image).save()->Chrome	✅	✅
pn.Row(hv.render(hv.Image)).save()->Chrome	❌	❌

It seems like the hv.render is producing the problem, as well as the odd case of holoviews & panel integration on VSCode.

Reproduction

I reproduced this error in a Colab notebook.

Here is a minimal code reproduction:

import holoviews as hv
import panel as pn
import numpy as np
from bokeh.plotting import show
from bokeh.io import output_notebook

def extension():
  hv.extension("bokeh")
  pn.extension()
  output_notebook()

ls = np.linspace(0, 10, 200)
xx, yy = np.meshgrid(ls, ls)
xy = np.sin(xx)*np.cos(yy)

hv.renderer('bokeh').theme = 'dark_minimal'
def dark_hv():
    return hv.Image(xy)
def dark_bk():
    return hv.render(dark_hv())
def dark_hv_pn():
    return pn.Row(dark_hv())
def dark_bk_pn():
    return pn.Row(dark_bk())

# Cell 1: Good
extension()
dark_hv()

# Cell 2: Wrong bgcolor
extension()
show(dark_bk())

# Cell 3: Good on Colab, Wrong bgcolor on VSCode
extension()
dark_hv_pn()

# Cell 4: Wrong bgcolor
extension()
dark_bk_pn()

# Cell 5
dark_bk_pn().save('dark_bk_pn.html')  # Wrong bgcolor
dark_hv_pn().save('dark_hv_pn.html')  # Good

I actually managed to bypass this issue in WaloViz with a custom holoviews hook, maybe it'll help with the investigation.

Screenshots

Good

Wrong bgcolor

Summary

• I may be interested in making a pull request to address this

Not gonna lie I'm a little out of my depth here, and I am not eager to dive in.
But if you can point out the possible causes for this issue and outline the solution I can help you out with the PR.