Scrolling when text draw in Jupyter output

[1ucian0]

This PR is an alternative solution to PR #1400.

When the circuit is draw in Jupyter, the output is wrapped in a <pre style="word-wrap: normal;white-space: pre;line-height: 15px;">, meaning that horizontal scrolling is allowed if needed. It looks like this:

[nonhermitian]

How about both this and #1400 with the option to select via wrap=True/False?

[1ucian0]

I have no problem. I'm honestly fine with whatever you think is the best for the Jupyter users. Maybe this can be activated with scroll=True/False instead of wrap (it seems more descriptive about the result to me)?

[ajavadia]

The mpl also wraps around. It would be nice if that also had this option.

[1ucian0]

Currently? I could not find any reference to wrap in qiskit/tools/visualization/_matplotlib.py...

[mtreinish]

It's in there, it's called fold and it's a value in the style dict kwarg: https://github.com/Qiskit/qiskit-terra/blob/master/qiskit/tools/visualization/_circuit_visualization.py#L163 It's a bit different though because it's a number of elements before folding/wrapping as opposed to the characters in the text output.

[mtreinish]

Also, I agree with @nonhermitian I don't think this is an alternative to #1400 it feels complementary to setting a fixed default for jupyter.

[1ucian0]

so.. fold is similar (opposite?) to line_length, right?

[mtreinish]

I'm fine with this as is. It is opt-in now that #1400 merged if you want a horizontally scrolling text visualization in jupyter you have to set the line_length to a large number or -1. Otherwise we'll line wrap by default at 80chars in jupyter.