Make selection have an exclusive end

[carlos-zamora]

Summary of the Pull Request

Selection is generally stored as a range of start and end where start <= end. However, this prevents the ability to have a selection be an empty range denoting the space between two cells. To fix this, we need to make the end exclusive.

References

Epic: #4993
Closes #13447

Detailed Description of the Pull Request / Additional comments

TODO CARLOS: I'll write this at some point, I swear.

Validation Steps Performed

• Rendering the selection

• Copying the selection

• Selection markers

• Keyboard Selection

mode	left	right	up	down
char	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅
word	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅
view	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅
buffer	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅	cursor: ✅ start: ✅ end: ✅

• Mouse selection

# of clicks	no movement	click + drag	shift + click
1	✅	✅	✅
2	✅	❓	✅
3	✅	❓	✅

• Block selection

  • alt + drag mouse
  • keyboard selection

• Corner cases:

  • wide glyphs
  • scrolling when keyboard selection goes to the top/bottom edge
  • click +drag to the left/right edge
  • keyboard selection when wrapping off the left/right edge

[carlos-zamora]

Why is this in draft?

• TODO CARLOS sprinkled throughout. I need to actually resolve or remove those.
• the tests probably need to be updated
• not all of my manual test cases have passed yet (see PR description)
• mouse selection feels really weird. I think this can be remedied by...
  • Mouse pointer should be text and not arrow one #1441 (PR Switch to the I-beam cursor when hovering over the terminal #5028)
    • NOTE: the issue here is that the mouse cursor shape is a Windows setting, so we need to keep track of when to change the cursor properly. There's also a lot of corner cases like VT Mouse Mode and multi-pane scenarios.
  • Mouse selection should begin and end at nearest cell boundary #5099
  • I'm hoping I can implement/prototype these, but we really need to polish this PR/change first before we move onto that. I think Mouse selection should begin and end at nearest cell boundary #5099 in particular will help a lot with making this feel more natural. Then Switch to the I-beam cursor when hovering over the terminal #5028 can be a bonus that anybody can really hop in and do.

[zadjii-msft]

Is this something we're targeting for 1.16 or 1.17?

[carlos-zamora]

Is this something we're targeting for 1.16 or 1.17?

We're gonna push this back to 1.17. Needs a lot of work, testing, and review.

That said, y'all should review it when you get the chance haha