[WIP] PR: Add multi-cursor editing to codeeditor

[athompson673]

Description of Changes

Multi-line editing has been a feature I've missed having in spyder for a long time. I frequently have a notepad++ scratchpad alongside spyder simply to copy blocks of text back and forth so that I can use the column cursor. I haven't been able to contribute money to the spyder project despite using it for about a decade now, but I can hopefully at least contribute some time.

I am an engineer, not a programmer so please criticize my work so we can make it better :)

I decided to implement the functionality directly inside the codeeditor.CodeEditor class as making it an editor extension would still require a great many edits to CodeEditor anyway. The basic implementation is to hide the original cursor when there are multiples, and manually draw the primary cursor and all extras on a timer. For many editor functions a for_each_cursor wrapper does a lot of heavy lifting. Other functions need to be slightly tweaked directly. I think it is not particularly productive to try to implement code completion (snippets, call-tips, etc) during multi-cursor sessions, so I attempt to disable those functions appropriately.

These are some deep changes to one of the most complicated parts of Spyder, so I will naturally need some help getting this code to a state where it's ready to be integrated. I know it is not yet fully ready, but I wanted to get the PR in so that more people could see it and maybe get interested in testing it.

Media1.mp4

TODO list:

• Ctrl-Alt click to add/remove cursor
• Ctrl-Alt-Shift click to add column cursor
• Add multi-cursor toggle to editor preferences
• Add selection highlight color to theme preferences?
• Handle cursors moving into folded code
• Render multiple cursors and selections
• render cursor when dragging text selection to new position
• Render overtype cursors (insert)
• Arrow keys, Home/End cursor movement
• Backspace / Delete
• Text typing
• Undo / Redo
• Cut Copy Paste
• Smart insertion of characters (colons, quotes, parenthesis, etc..)
• Smart backspace
• Automatic whitespace insertion
• Cursor position history
• Last edit position
• How to deal with auto-completions, call tips, snippets, etc. (disable them basically)
• Write many tests
• Documentation on multi-cursor usage (hints on settings toggle tooltip?)
• Evaluate all shortcuts (add multi-cursor handling, only handle primary cursor, or disable when multi-cursor):
  • code completion
  • duplicate line up/down
  • delete line
  • move line up/down
  • go to new line/line number/definition (from cursor)/next, previous cell
  • toggle comment
  • create new cell
  • (un)blockcomment
  • transform to upper/lowercase
  • (un)indent
  • start/end of document
  • start/end, prev/next line
  • prev/next char/word
  • next/prev warning
  • killring
  • undo/redo
  • cut/copy/paste
  • delete
  • select all
  • docstring
  • autoformatting
  • scroll line up/down
  • enter array inline/table
  • inspect current object
  • last edit location
  • next/prev cursor position
  • Run Cell (and advance) (in debugger)
  • Run Selection (and advance) (from line) (in debugger) (up to line)

Issue(s) Resolved

Fixes #2112

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: athompson673

[pep8speaks]

Hello @athompson673! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file spyder/plugins/editor/widgets/codeeditor/tests/test_multicursor.py:

Line 39:1: E302 expected 2 blank lines, found 1
Line 61:1: E305 expected 2 blank lines after class or function definition, found 1

Comment last updated at 2024-12-03 00:01:06 UTC

[athompson673]

I am running into difficulty figuring out how to handle folded code blocks with the move/duplicate line up/down functions. It seems difficult to prevent edge cases from breaking the code folding state. Does anyone have experience with that system?

[athompson673]

@ccordoba12 any idea why the starter test file I wrote won't seem to send a mousePress event? I didn't think I'd hit a brick wall quite so soon in trying to start writing my own tests...

It fails on the assert bool(code_editor.extra_cursors) and adding a print statement in CodeEditor.mousePressEvent doesn't show standard output in pytest.

[ccordoba12]

I am running into difficulty figuring out how to handle folded code blocks with the move/duplicate line up/down functions. It seems difficult to prevent edge cases from breaking the code folding state. Does anyone have experience with that system?

I am the one with more experience in that system. What's exactly the problem you're seeing?

@ccordoba12 any idea why the starter test file I wrote won't seem to send a mousePress event? I didn't think I'd hit a brick wall quite so soon in trying to start writing my own tests...

It seems mousePress requires to use as widget the editor's viewport, like this:

spyder/spyder/plugins/editor/panels/tests/test_scrollflag.py

Lines 238 to 240 in 9b43b71

	with qtbot.waitSignal(editor.sig_alt_left_mouse_pressed, raising=True):
	qtbot.mousePress(editor.viewport(), Qt.LeftButton,
	Qt.AltModifier, QPoint(w//2, h//2))

Have you also tried mouseClick?

[athompson673]

I am running into difficulty figuring out how to handle folded code blocks with the move/duplicate line up/down functions. It seems difficult to prevent edge cases from breaking the code folding state. Does anyone have experience with that system?

I am the one with more experience in that system. What's exactly the problem you're seeing?

I think I got to an acceptable solution with move_line_up and move_line_down, but duplicating a folded line up or down breaks the folding state.

Example: duplicate folded line

Media1.mp4

@ccordoba12 any idea why the starter test file I wrote won't seem to send a mousePress event? I didn't think I'd hit a brick wall quite so soon in trying to start writing my own tests...

It seems mousePress requires to use as widget the editor's viewport, like this:

spyder/spyder/plugins/editor/panels/tests/test_scrollflag.py

Lines 238 to 240 in 9b43b71

	with qtbot.waitSignal(editor.sig_alt_left_mouse_pressed, raising=True):
	qtbot.mousePress(editor.viewport(), Qt.LeftButton,
	Qt.AltModifier, QPoint(w//2, h//2))

Have you also tried mouseClick?

I started with mouseClick and was trying several things.. viewport() seems to have worked, Thanks! (though now it would seem I'm calculating the position of the desired click wrong nvm fixed)