COOKED_READ_DATA: Fix scrolling under ConPTY #15930
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Sep 6, 2023
| @@ -3401,7 +3401,7 @@ void ConptyRoundtripTests::WrapNewLineAtBottomLikeMSYS() | |||
| } | |||
| else if (writingMethod == PrintWithWriteCharsLegacy) | |||
| { | |||
| WriteCharsLegacy(si, str, true, nullptr); | |||
| WriteCharsLegacy(si, str, false, nullptr); | |||
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This makes the tests pass. I don't think they ever relied on the interactive behavior of WriteCharsLegacy.
| @@ -752,7 +752,7 @@ void COOKED_READ_DATA::_flushBuffer() | |||
| const auto distanceBeforeCursor = _writeChars(view.substr(0, _bufferCursor)); | |||
| const auto distanceAfterCursor = _writeChars(view.substr(_bufferCursor)); | |||
| const auto distanceEnd = distanceBeforeCursor + distanceAfterCursor; | |||
| const auto eraseDistance = std::max(0, _distanceEnd - distanceEnd); | |||
| const auto eraseDistance = std::max<ptrdiff_t>(0, _distanceEnd - distanceEnd); | |||
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After a lot of back and forth, I went with ptrdiff_t after all. That way we can have bigger buffers in the future and make full use of our int32_t coordinates.
| const auto initialCursorPos = cursor.GetPosition(); | ||
| til::CoordType scrollY = 0; | ||
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| WriteCharsLegacy(_screenInfo, text, true, &scrollY); | ||
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| const auto finalCursorPos = cursor.GetPosition(); | ||
| return (finalCursorPos.y - initialCursorPos.y + scrollY) * width + finalCursorPos.x - initialCursorPos.x; | ||
| const auto distance = (finalCursorPos.y - initialCursorPos.y + scrollY) * width + finalCursorPos.x - initialCursorPos.x; | ||
| assert(distance >= 0); |
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This helped me find the 2nd bug.
Comment on lines
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| ptrdiff_t _distanceCursor = 0; | ||
| ptrdiff_t _distanceEnd = 0; |
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Whoops. Forgot to 0 initialize.
carlos-zamora
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Sep 7, 2023
DHowett
approved these changes
Sep 8, 2023
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This commit fixes 3 bugs:
COOKED_READ_DATAfailed to initialize its_distanceCursorand_distanceEndmembers. I took this as an opportunity to make themptrdiff_t, to reduce the likelihood of overflows in the future.COOKED_READ_DATA::_writeCharsaddedscrollYto the writtendistance, even though
WriteCharsLegacywrites a negative value intothat out parameter. This was fixed by changing
WriteCharsLegacytowrite positive values and by adding a debug assertion.
StreamScrollRegioncallsIncrementCircularBufferwhich causes asynchronous (!) ConPTY flush to the output pipe (side note: this is
the primary reason why newlines are so slow in ConPTY).
Since cooked reads are supposed to behave like a pager and not write
into the scrollback, we temporarily mark the buffer as inactive
which prevents
TextBufferfrom snitching about it to VtEngine.Even after this change, there's still some weird behavior left:
real pager-like implementation. That might be a neat future extension.
cursor and scroll the buffer, unless the cursor is at the end.
That might also be worth investigating in the future (minor issue).
(using Ctrl+Backspace) doesn't erase all of the affected lines,
because
COOKED_READ_DATA::_eraseuses the sameWriteCharsLegacyfunction to write whitespace to erase that text. It's only gone
after typing one more character.
I've written the code to mostly fix this, but decided against it
as I considered the problem to be too niche to warrant extra code.
Closes #15899
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