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[Scenario] 2 Resize 2 Reflow #5800

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8 of 31 tasks
zadjii-msft opened this issue May 7, 2020 · 1 comment
Open
8 of 31 tasks

[Scenario] 2 Resize 2 Reflow #5800

zadjii-msft opened this issue May 7, 2020 · 1 comment
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Area-CodeHealth Issues related to code cleanliness, linting, rules, warnings, errors, static analysis, etc. Issue-Scenario Product-Conpty For console issues specifically related to conpty
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@zadjii-msft
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zadjii-msft commented May 7, 2020

During 1.0, we discovered a ton of bugs in our resize with reflow implementation, and now that we need to keep both the conpty and the terminal in sync on these things, it's more important than ever to do these things right.

I'm collecting up all the straggling tasks I've found that might possibly be related.

This is a combo of "Make Reflow work correctly", and "Get rid of the spaghetti in the VtEngine related to line wrapping"

(see also #4200, the original reflow mega thread)

Issues

Things I think will all be fixed by #8000

PRs

Many of these are 1.0 PRs, but they've all got important context.

1.0 PRs
@ghost ghost added Needs-Triage It's a new issue that the core contributor team needs to triage at the next triage meeting Needs-Tag-Fix Doesn't match tag requirements labels May 7, 2020
@DHowett-MSFT DHowett-MSFT removed the Needs-Triage It's a new issue that the core contributor team needs to triage at the next triage meeting label May 8, 2020
@zadjii-msft zadjii-msft changed the title [Reserved for future use] [Scenario] 2 Resize 2 Reflow May 12, 2020
@zadjii-msft zadjii-msft added Area-CodeHealth Issues related to code cleanliness, linting, rules, warnings, errors, static analysis, etc. Issue-Scenario Product-Conpty For console issues specifically related to conpty labels May 12, 2020
@ghost ghost removed the Needs-Tag-Fix Doesn't match tag requirements label May 12, 2020
@miniksa
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miniksa commented May 12, 2020

2 Resize 2 Reflow

I'm pretty sure we're at least on Resize & Reflow: Tokyo Drift by now if not further into the series.

@DHowett-MSFT DHowett-MSFT added this to the Terminal Backlog milestone May 12, 2020
DHowett-MSFT pushed a commit that referenced this issue May 12, 2020
This PR reverts a relatively minor change that was made incorrectly to
ConPTY in #5771.

In that PR, I authored two tests. One of them actually caught the bug
that was supposed to be fixed by #5771. The other test was simply
authored during the investigation. I believed at the time that the test
revealed a bug in conpty that was fixed by _removing_ this block of
code. However, an investigation itno #5839 revealed that this code was
actually fairly critical. 

So, I'm also _skipping_ this buggy test for now. I'm also adding a
specific test case to this bug.

The problem in the bugged case of `WrapNewLineAtBottom` is that
`WriteCharsLegacy` is wrapping the bottom row of the ConPTY buffer,
which is causing the cursor to automatically move to the next line in
the buffer. This is because `WriteCharsLegacy` isn't being called with
the `WC_DELAY_EOL_WRAP` flag. So, in that test case, 
* The client emits a wrapped line to conpty
* conpty fills the bottom line with that text, then dutifully increments
  the buffer to make space for the cursor on a _new_ bottom line.
* Conpty reprints the last `~` of the wrapped line
* Then it gets to the next line, which is being painted _before_ the
  client emits the rest of the line of text to fill that row.
* Conpty thinks this row is empty, (it is) and manually breaks the row. 

However, the test expects this row to be emitted as wrapped. The problem
comes from the torn state in the middle of these frames - the original
line probably _should_ remain wrapped, but this is a sufficiently rare
case that the fix is being punted into the next release. 

It's possible that improving how we handle line wrapping might also fix
this case - currently we're only marking a row as wrapped when we print
the last cell of a row, but we should probably mark it as wrapped
instead when we print the first char of the _following_ row. That work
is being tracked in #5800

### The real bug in this PR

The problem in the `DeleteWrappedWord` test is that the first line is
still being marked as wrapped. So when we get to painting the line below
it, we'll see that there are no characters to be printed (only spaces),
we emit a `^[20X^[20C`, but the cursor is still at the end of the first
line. Because it's there, we don't actually clear the text we want to
clear.

So DeleteWrappedWord, #5839 needs the `_wrappedRow = std::nullopt;`
statement here.

## References
* I guess just look at #5800, I put everything in there.

## Validation Steps Performed
* Tested manually that this was fixed for the Terminal
* ran tests

Closes #5839
DHowett-MSFT pushed a commit that referenced this issue May 12, 2020
This PR reverts a relatively minor change that was made incorrectly to
ConPTY in #5771.

In that PR, I authored two tests. One of them actually caught the bug
that was supposed to be fixed by #5771. The other test was simply
authored during the investigation. I believed at the time that the test
revealed a bug in conpty that was fixed by _removing_ this block of
code. However, an investigation itno #5839 revealed that this code was
actually fairly critical.

So, I'm also _skipping_ this buggy test for now. I'm also adding a
specific test case to this bug.

The problem in the bugged case of `WrapNewLineAtBottom` is that
`WriteCharsLegacy` is wrapping the bottom row of the ConPTY buffer,
which is causing the cursor to automatically move to the next line in
the buffer. This is because `WriteCharsLegacy` isn't being called with
the `WC_DELAY_EOL_WRAP` flag. So, in that test case,
* The client emits a wrapped line to conpty
* conpty fills the bottom line with that text, then dutifully increments
  the buffer to make space for the cursor on a _new_ bottom line.
* Conpty reprints the last `~` of the wrapped line
* Then it gets to the next line, which is being painted _before_ the
  client emits the rest of the line of text to fill that row.
* Conpty thinks this row is empty, (it is) and manually breaks the row.

However, the test expects this row to be emitted as wrapped. The problem
comes from the torn state in the middle of these frames - the original
line probably _should_ remain wrapped, but this is a sufficiently rare
case that the fix is being punted into the next release.

It's possible that improving how we handle line wrapping might also fix
this case - currently we're only marking a row as wrapped when we print
the last cell of a row, but we should probably mark it as wrapped
instead when we print the first char of the _following_ row. That work
is being tracked in #5800

### The real bug in this PR

The problem in the `DeleteWrappedWord` test is that the first line is
still being marked as wrapped. So when we get to painting the line below
it, we'll see that there are no characters to be printed (only spaces),
we emit a `^[20X^[20C`, but the cursor is still at the end of the first
line. Because it's there, we don't actually clear the text we want to
clear.

So DeleteWrappedWord, #5839 needs the `_wrappedRow = std::nullopt;`
statement here.

## References
* I guess just look at #5800, I put everything in there.

## Validation Steps Performed
* Tested manually that this was fixed for the Terminal
* ran tests

Closes #5839

(cherry picked from commit b4c33dd)
jelster pushed a commit to jelster/terminal that referenced this issue May 28, 2020
This PR reverts a relatively minor change that was made incorrectly to
ConPTY in microsoft#5771.

In that PR, I authored two tests. One of them actually caught the bug
that was supposed to be fixed by microsoft#5771. The other test was simply
authored during the investigation. I believed at the time that the test
revealed a bug in conpty that was fixed by _removing_ this block of
code. However, an investigation itno microsoft#5839 revealed that this code was
actually fairly critical. 

So, I'm also _skipping_ this buggy test for now. I'm also adding a
specific test case to this bug.

The problem in the bugged case of `WrapNewLineAtBottom` is that
`WriteCharsLegacy` is wrapping the bottom row of the ConPTY buffer,
which is causing the cursor to automatically move to the next line in
the buffer. This is because `WriteCharsLegacy` isn't being called with
the `WC_DELAY_EOL_WRAP` flag. So, in that test case, 
* The client emits a wrapped line to conpty
* conpty fills the bottom line with that text, then dutifully increments
  the buffer to make space for the cursor on a _new_ bottom line.
* Conpty reprints the last `~` of the wrapped line
* Then it gets to the next line, which is being painted _before_ the
  client emits the rest of the line of text to fill that row.
* Conpty thinks this row is empty, (it is) and manually breaks the row. 

However, the test expects this row to be emitted as wrapped. The problem
comes from the torn state in the middle of these frames - the original
line probably _should_ remain wrapped, but this is a sufficiently rare
case that the fix is being punted into the next release. 

It's possible that improving how we handle line wrapping might also fix
this case - currently we're only marking a row as wrapped when we print
the last cell of a row, but we should probably mark it as wrapped
instead when we print the first char of the _following_ row. That work
is being tracked in microsoft#5800

### The real bug in this PR

The problem in the `DeleteWrappedWord` test is that the first line is
still being marked as wrapped. So when we get to painting the line below
it, we'll see that there are no characters to be printed (only spaces),
we emit a `^[20X^[20C`, but the cursor is still at the end of the first
line. Because it's there, we don't actually clear the text we want to
clear.

So DeleteWrappedWord, microsoft#5839 needs the `_wrappedRow = std::nullopt;`
statement here.

## References
* I guess just look at microsoft#5800, I put everything in there.

## Validation Steps Performed
* Tested manually that this was fixed for the Terminal
* ran tests

Closes microsoft#5839
@zadjii-msft zadjii-msft modified the milestones: Terminal Backlog, Backlog Jan 4, 2022
DHowett pushed a commit that referenced this issue Sep 26, 2023
Subjectively speaking, this commit makes 3 improvements:
* Most importantly, it now would work with arbitrary Unicode text.
  (No more `IsGlyphFullWidth` or DBCS handling during reflow.)
* Due to the simpler implementation it hopefully makes review of
  future changes and maintenance simpler. (~3x less LOC.)
* It improves perf. by 1-2 orders of magnitude.
  (At 120x9001 with a full buffer I get 60ms -> 2ms.)

Unfortunately, I'm not confident that the new code replicates the old
code exactly, because I failed to understand it. During development
I simply tried to match its behavior with what I think reflow should do.

Closes #797
Closes #3088
Closes #4968
Closes #6546
Closes #6901
Closes #15964
Closes MSFT:19446208

Related to #5800 and #8000

## Validation Steps Performed
* Unit tests ✅
* Feature tests ✅
* Reflow with a scrollback ✅
* Reflowing the cursor cell causes a forced line-wrap ✅
  (Even at the end of the buffer. ✅)
* `color 8f` and reflowing retains the background color ✅
* Enter alt buffer, Resize window, Exit alt buffer ✅
DHowett pushed a commit that referenced this issue Sep 26, 2023
Subjectively speaking, this commit makes 3 improvements:
* Most importantly, it now would work with arbitrary Unicode text.
  (No more `IsGlyphFullWidth` or DBCS handling during reflow.)
* Due to the simpler implementation it hopefully makes review of
  future changes and maintenance simpler. (~3x less LOC.)
* It improves perf. by 1-2 orders of magnitude.
  (At 120x9001 with a full buffer I get 60ms -> 2ms.)

Unfortunately, I'm not confident that the new code replicates the old
code exactly, because I failed to understand it. During development
I simply tried to match its behavior with what I think reflow should do.

Closes #797
Closes #3088
Closes #4968
Closes #6546
Closes #6901
Closes #15964
Closes MSFT:19446208

Related to #5800 and #8000

## Validation Steps Performed
* Unit tests ✅
* Feature tests ✅
* Reflow with a scrollback ✅
* Reflowing the cursor cell causes a forced line-wrap ✅
  (Even at the end of the buffer. ✅)
* `color 8f` and reflowing retains the background color ✅
* Enter alt buffer, Resize window, Exit alt buffer ✅

(cherry picked from commit 7474839)
Service-Card-Id: 90642727
Service-Version: 1.19
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