Implement Window/Page scroll commands

[sandy081]

These commands are needed for Vim:

From VSCodeVim/Vim#210:

Vim has handy commands for scrolling without moving the cursor, e.g. zt, which scrolls the screen so that the line with the current cursor is placed as the first line. E.g., I often do actions like /main(zt, so that I can see as much of the main function as possible.

Would it be possible to implement zt, zb and zz?

Thanks!

• Scroll window upwards/downwards by lines (real line) or window size (eg, half window size)

executeCommand('editorScroll', {to: 'up', by: 'line', value: 10, revealCursor?: false});

'to'

• up
• down

'by'

• line
• wrappedLine
• page
• halfPage

'revealCursor'

• If true reveals the cursor while scrolling otherwise does not.
• Scroll line to a specific position of the window

executeCommand('revealLine', {lineNumber: 10, at: 'top'});

'at'

• top
• center
• bottom
• Scroll horizontal scrollbar by column numbers.
  Horizontal scrolling is already implemented by cursor move commands. Hence marking this done. See VIM API Gaps #8997

[rebornix]

About the first task, just realized that we have scrollLineUp scrollLineDown, scrollPageUp and scrollPageDown commands already. The only part missing is scrolling half page down.

Users are allowed to scroll line up or down with numeric prefix, like 10 Ctrl-E to scroll ten lines down. If we repeat scrollLineUp ten times, I'm worried we might have performance hit somehow. So a generic command takes line number as argument will be better IMHO.

[sandy081]

@rebornix Delivered a new command called editorScroll. Try it and let me know the feedback. See the description for usage.
Thanks

[rebornix]

@sandy081 I just ran your commands but see below errors

error.stack
Error: argument does not match one of these constraints: arg instanceof constraint, arg.constructor === constraint, nor constraint(arg) === true
    at f (file:///C:/Program Files (x86)/Microsoft VS Code Insiders/resources/app/out/vs/workbench/workbench.main.js:29:13605)

any idea?

[sandy081]

@rebornix Hmm strange, I do not see any issue while using this command in our sample Vim extension. Can you show me how are you calling this command?