Enable the user to get lines from a pane via cli

[emilycares]

This feature exists in tmux implementation and i also wanted to use it in wezterm.

[wez]

Thanks for this, but I don't think this will behave how you want; GetLines::lines are StableRowIndex values which are offsets from the first ever row of scrollback. When more than scrollback_lines are received, StableRowIndex = 0 will no longer be a resolvable line in the way that you want.

To work without surprises, I think you'll want to retrieve the RenderableDimensions so that you can reason about the range of lines to using either scrollback_top or physical_top as the starting index, then adding the number of lines to it. RenderableDimensions would also allow you to make it easy to select either the viewport (viewport_rows) or full scrollback (scrollback_rows) with convenient flags.

There isn't currently a way to return just RenderableDimensions in the rpc/codec stuff, so you'd need to add that functionality!

Something else that I think would be great to consider around this allowing the user to select from:

• physical lines (what you're currently retrieving)
• logical lines

And:

• Getting just text (eg: https://wezfurlong.org/wezterm/config/lua/window/get_selection_text_for_pane.html)
• Getting the text with escapes (eg: https://wezfurlong.org/wezterm/config/lua/window/get_selection_escapes_for_pane.html)

[emilycares]

Thanks for looking at my pr. I have tried to implement your suggestion. The history of the output also looks fine.

[wez]

Sorry; I'd forgotten about this, and when I sat down to write up the review I figured I may was well just write the code, so I just pushed a version of wezterm cli get-text. I'd appreciate your feedback on it!