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UI Automation in Windows Console: Disable visible range bounding on 21H1 and later#11495

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UI Automation in Windows Console: Disable visible range bounding on 21H1 and later#11495
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@codeofdusk

@codeofdusk codeofdusk commented Aug 15, 2020 •
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Link to issue number:

Blocked by microsoft/terminal#6986.

Summary of the issue:

It was mentioned in microsoft/terminal#6453 (comment) that some new console text can actually appear below the visible range, making it completely inaccessible to NVDA.

Description of how this pull request fixes the issue:

No longer bound the console's text info to the visible ranges on 21H1 and later. This will require upstream changes by Microsoft to maintain usability in the console after this PR.

Testing performed:

  • Adjusted winConsoleUIA._getTextLines to limit the number of lines in the diff and tested the case in UIA in conhost: issues with visible ranges microsoft/terminal#5481. Observed that the bug is no longer reproducible.
  • Tested that pre-21H1 UIA consoles still work as expected (word navigation, bounding, going to the ends of the console).

Known issues with pull request:

  • There are thousands upon thousands of blank lines in the output, slowing down the diffing algorithm to the point that the console is unusable. Switching to DMP makes the console usable but with a noticeable brief lag.
  • Moving the review cursor to the bottom of the console crashes it. I'll file an upstream bug.

Change log entry:

Not user visible.

@codeofdusk

codeofdusk commented Aug 15, 2020

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Cc @carlos-zamora, @DHowett, @michaelDCurran.

@LeonarddeR

LeonarddeR commented Aug 15, 2020

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Please describe the underlying issue with NVDA along with steps to reproduce. Also, it would help if you could provide info on how Narrator behaves in this case.

@codeofdusk

codeofdusk commented Aug 16, 2020

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From microsoft/terminal#5481:

Environment

Windows build number: [run `[Environment]::OSVersion` for powershell, or `ver` for cmd] next (19613.1000).
Windows Terminal version (if applicable): Inbox console

Any other software? NVDA

Steps to reproduce

  1. Download this list of domains.

  2. Start Windows Console and NVDA (with UIA in Windows Console enabled in advanced preferences).

  3. Run a python interpreter: python.

  4. Run:

    fin=open("domains.txt")
    fin.readlines()

Expected behaviour

Like in pre-21H1 conhost and Windows Terminal 0.11, NVDA reads current output immediately.

Actual behaviour

At this point, NVDA's auto-read lags far behind the actual output in the buffer. Quitting Python with quit() continues reading very old output.

Context

When a text change event is received, NVDA takes a diff of the old and new text and reads only the changed portion of the text. Maybe there's a bug in our diffing algorithm (implemented here, in LiveText._calculateNewText)?

@codeofdusk codeofdusk mentioned this pull request Sep 22, 2020
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@codeofdusk

codeofdusk commented Sep 22, 2020

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Closing in favour of a solution to #11172.

@codeofdusk codeofdusk closed this Sep 22, 2020
@codeofdusk codeofdusk mentioned this pull request May 17, 2021
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@codeofdusk codeofdusk mentioned this pull request Jul 22, 2021
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@codeofdusk @LeonarddeR