[BUG] HoverTool in 'vline' mode doesn't work with vertical segments

Bokeh version: 1.4 Python version: 3.7.5 Browser: Firefox / Chromium OS: Linux

When adding a HoverTool with mode='vline' to a plot with vertical segments, the tooltip is not displayed.

Example code:

from bokeh.io import output_file, save
from bokeh.models import HoverTool
from bokeh.plotting import figure

x = [1, 2, 3, 4]
y0 = [1] * 4
y1 = [2] * 4
fig = figure(tools=[HoverTool(mode='vline')])
fig.segment(x, y0, x, y1)
output_file('vline.html')
save(fig)

Screenshot:

[bryevdv]

OK well let’s make a PR and go from there (the other reason to make a PR earlier is that it is much easier for other people to try out a PR)

[bryevdv]

@kumaran-14 the span coordinate geometry comes in as pixel coordinates. You can see that scale invert function is use to convert to back to “data space” (so that the spatial index an be used to get a first batch of potential hits). Scales also have a compute method, which goes in the opposite direction, converting from data space to pixel space. You can use that to convert segment data coordinates to pixel coordinates in a similar way, for the final comparison.