Add support for grouping tools in plots

[mattpap]

Allows to group common tools in plots and figures (in bokehjs). Adds new Toolbar.group and Toolbar.group_types properties. See the new example/interaction/tools/tool_grouping.py example:

Screencast.from.2025-01-31.10-52-08.webm

fixes #5497

[mattpap]

Tentatively ready for review. I need to add tests.

[hoxbro]

TapTool does not seem to behave as expected:

Screencast.From.2025-02-03.16-41-34.mp4

code

from bokeh.layouts import column, row
from bokeh.models import CustomJS, Div, HoverTool, Switch, TapTool
from bokeh.plotting import figure, show

plot = figure(width=400, height=400, tools=["pan", "box_select", "save", "reset"])

cr1 = plot.scatter([1, 2, 3], [3, 3, 3], size=30, color="red")
cr2 = plot.scatter([1, 2, 3], [2, 2, 2], size=30, color="green")
cr3 = plot.scatter([1, 2, 3], [1, 1, 1], size=30, color="blue")

plot.add_tools(HoverTool(renderers=[cr1], description="Hover over red"))
plot.add_tools(HoverTool(renderers=[cr2], description="Hover over green"))
plot.add_tools(HoverTool(renderers=[cr3], description="Hover over blue"))

plot.add_tools(TapTool(renderers=[cr1], description="Tap on red"))
plot.add_tools(TapTool(renderers=[cr2], description="Tap on green"))
plot.add_tools(TapTool(renderers=[cr3], description="Tap on blue"))

text = Div(text="Group tools:")
switch = Switch(active=plot.toolbar.group)
switch.js_on_change("active", CustomJS(args=dict(plot=plot), code="""
export default ({plot}, {active: group}) => {
    plot.toolbar.group = group
}
"""))
layout = column([row([text, switch]), plot])

show(layout)

Also, is there a way to group two out of three hover tools? It's a bit hard to tell if this is the case.

[mattpap]

TapTool does not seem to behave as expected:

I forgot that you can't have multiple tap tools active at the same time (issue #3804). I suppose I will fix that next.

[mattpap]

Also, is there a way to group two out of three hover tools? It's a bit hard to tell if this is the case.

Currently not. Any suggestions regarding the API for this?

[hoxbro]

Any suggestions regarding the API for this?

At the top of my head, it would be something like this:

plot.add_tools(HoverTool(renderers=[cr1], description="Hover over red", group="one"))
plot.add_tools(HoverTool(renderers=[cr2], description="Hover over green", group="one"))
plot.add_tools(HoverTool(renderers=[cr3], description="Hover over blue", group="two"))

The same group (it could be another name) for the tool would be merged. If group is not added, it would merge all.

[mattpap]

The same group (it could be another name) for the tool would be merged. If group is not added, it would merge all.

I was going to do exactly that.

[mattpap]

I added support for Tool.group and removed "tap" from Toolbar.group_types for now:

Screencast.from.2025-02-04.12-14-49.webm

I also added support for indication of the number of tools being grouped.

[hoxbro]

I also added support for indication of the number of tools being grouped.

I think this should be disabled by default (if it is not already). From a user perspective, it would confuse as there is nothing the user can do with the information.

[mattpap]

I think this should be disabled by default (if it is not already). From a user perspective, it would confuse as there is nothing the user can do with the information.

This gives the user indication that they work with multiple tools at once. This will be more useful when I will implement implement partial active state (for when only a subset of tool group's tools is active) and a menu with access to individual tools. Note that this doesn't affect proxies in grid plot (etc.) toolbars.

[mattpap]

I hid the tool tool counter for now. I will revisit this when implementing individual tool access in tool group buttons via a menu.

[hoxbro]

LGTM

Very happy to see the added comments in the code 👍

[hoxbro]

Suggested change

	plot.add_tools(
	# The description will be shown when hovering over the tool icon
	plot.add_tools(

[github-actions]

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