starred/terminal
1
0
Fork 0
mirror of https://github.com/microsoft/terminal.git synced 2026-02-03 21:25:34 +00:00
Code Issues 19.0k Packages Projects Releases 20 Wiki Activity

[PR #12358] Use UIA notifications for text output #29008

New Issue
Open
opened 2026-01-31 09:32:12 +00:00 by claunia · 0 comments
claunia commented 2026-01-31 09:32:12 +00:00
Owner
Copy Link

Original Pull Request: https://github.com/microsoft/terminal/pull/12358

State: closed
Merged: Yes

Summary of the Pull Request

This change makes Windows Terminal raise a RaiseNotificationEvent() (docs) for new text output to the buffer.

This is intended to help Narrator identify what new output appears and reduce the workload of diffing the buffer when a TextChanged event occurs.

Detailed Description of the Pull Request / Additional comments

The flow of the event occurs as follows:

  • Terminal::_WriteBuffer()
    • New text is output to the text buffer. Notify the renderer that we have new text (and what that text is).
  • Renderer::TriggerNewTextNotification()
    • Cycle through all the rendering engines and tell them to notify handle the new text output.
    • None of the rendering engines except UiaEngine has it implemented, so really we're just notifying UIA.
  • UiaEngine::NotifyNewText()
    • Concatenate any new output into a string.
    • When we're done painting, tell the notification system to actually notify of new events occurring and clear any stored output text. That way, we're ready for the next renderer frame.
  • InteractivityAutomationPeer::NotifyNewOutput() --> TermControlAutomationPeer::NotifyNewOutput
    • NOTE: these are split because of the in-proc and out-of-proc separation of the buffer.
    • Actually RaiseNotificationEvent() for the new text output.

Additionally, we had to handle the "local echo" problem: when a key is pressed, the character is said twice (once for the keyboard event, and again for the character being written to the buffer). To accomplish this, we did the following:

  • TermControl:
    • here, we already handle keyboard events, so I added a line saying "if we have an automation peer attached, record the keyboard event in the automation peer".
  • TermControlAutomationPeer:
    • just before the notification is dispatched, check if the string of recent keyboard events match the beginning of the string of new output. If that's the case, we can assume that the common prefix was the "local echo".

This is a fairly naive heuristic, but it's been working.

Closes the following ADO bugs:

Test cases

  • Base case: "echo hello"
  • Partial line change
  • Scrolling (should be unaffected)
  • Large output
  • "local echo": keyboard events read input character twice
**Original Pull Request:** https://github.com/microsoft/terminal/pull/12358 **State:** closed **Merged:** Yes --- ## Summary of the Pull Request This change makes Windows Terminal raise a `RaiseNotificationEvent()` ([docs](https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.automation.peers.automationpeer.raisenotificationevent?view=winrt-22000)) for new text output to the buffer. This is intended to help Narrator identify what new output appears and reduce the workload of diffing the buffer when a `TextChanged` event occurs. ## Detailed Description of the Pull Request / Additional comments The flow of the event occurs as follows: - `Terminal::_WriteBuffer()` - New text is output to the text buffer. Notify the renderer that we have new text (and what that text is). - `Renderer::TriggerNewTextNotification()` - Cycle through all the rendering engines and tell them to notify handle the new text output. - None of the rendering engines _except_ `UiaEngine` has it implemented, so really we're just notifying UIA. - `UiaEngine::NotifyNewText()` - Concatenate any new output into a string. - When we're done painting, tell the notification system to actually notify of new events occurring and clear any stored output text. That way, we're ready for the next renderer frame. - `InteractivityAutomationPeer::NotifyNewOutput()` --> `TermControlAutomationPeer::NotifyNewOutput` - NOTE: these are split because of the in-proc and out-of-proc separation of the buffer. - Actually `RaiseNotificationEvent()` for the new text output. Additionally, we had to handle the "local echo" problem: when a key is pressed, the character is said twice (once for the keyboard event, and again for the character being written to the buffer). To accomplish this, we did the following: - `TermControl`: - here, we already handle keyboard events, so I added a line saying "if we have an automation peer attached, record the keyboard event in the automation peer". - `TermControlAutomationPeer`: - just before the notification is dispatched, check if the string of recent keyboard events match the beginning of the string of new output. If that's the case, we can assume that the common prefix was the "local echo". This is a fairly naive heuristic, but it's been working. Closes the following ADO bugs: - https://dev.azure.com/microsoft/OS/_workitems/edit/36506838 - (Probably) https://dev.azure.com/microsoft/OS/_workitems/edit/38011453 ## Test cases - [x] Base case: "echo hello" - [x] Partial line change - [x] Scrolling (should be unaffected) - [x] Large output - [x] "local echo": keyboard events read input character twice
claunia added the pull-request label 2026-01-31 09:32:12 +00:00
Sign in to join this conversation.
No Branch/Tag Specified
Branches Tags
Labels
Clear labels
⛺ Reserved
A11yCO
A11yMAS
A11ySev1
A11ySev2
A11ySev3
A11yTTValidated
A11yUsable
A11yVoiceAccess
A11yWCAG
Area-Accessibility
Area-AtlasEngine
Area-AzureShell
Area-Build
Area-Build
Area-Chat
Area-CmdPal
Area-CodeHealth
Area-Commandline
Area-CookedRead
Area-DefApp
Area-Extensibility
Area-Fonts
Area-GroupPolicy
Area-i18n
Area-Input
Area-Interaction
Area-Interop
Area-Localization
Area-Output
Area-Performance
Area-Portable
Area-Quality
Area-Remoting
Area-Rendering
Area-Schema
Area-Server
Area-Settings
Area-SettingsUI
Area-ShellExtension
Area-ShellExtension
Area-ShellExtension
Area-Suggestions
Area-Suggestions
Area-TerminalConnection
Area-TerminalControl
Area-Theming
Area-UserInterface
Area-VT
Area-Windowing
Area-WPFControl
AutoMerge
Blocking-Ingestion
Culprit-Centennial
Culprit-WinUI
Disability-All
Disability-Blind
Disability-LowVision
Disability-Mobility
External-Blocked-WinUI3
Fixed
Gathering-Data
good first issue
HCL-E+D
HCL-WindowsTerminal
Help Wanted
Impact-Compatibility
Impact-Compliance
Impact-Correctness
Impact-Visual
In-PR
InclusionBacklog
InclusionBacklog-Windows TerminalWin32
InclusionCommitted-202206
Issue-Bug
Issue-Docs
Issue-Feature
Issue-Feature
Issue-Question
Issue-Samples
Issue-Scenario
Issue-Task
Needs-Attention
Needs-Author-Feedback
Needs-Bisect
Needs-Discussion
Needs-Repro
Needs-Tag-Fix
Needs-Tag-Fix
Needs-Triage
No-Recent-Activity
Priority-0
Priority-1
Priority-2
Priority-3
Product-Cmd.exe
Product-Colortool
Product-Colortool
Product-Colortool
Product-Conhost
Product-Conpty
Product-Meta
Product-Powershell
Product-Terminal
Product-WSL
pull-request
Mirrored from GitHub Pull Request
 Resolution-Answered
Resolution-By-Design
Resolution-Duplicate
Resolution-External
Resolution-Fix-Available
Resolution-Fix-Committed
Resolution-No-Repro
Resolution-Won't-Fix
Severity-Blocking
Severity-Crash
Severity-DataLoss
spam
this-will-be-a-breaking-change
Tracking-External
WindowsTerminal_Win32
Work-Item
zAskModeBug
zInbox-Bug
No Label pull-request
Milestone
No items
No Milestone
Projects
Clear projects
No project
Assignees
Clear assignees
claunia
No Assignees
1 Participants
Notifications
Due Date
No due date set.
Dependencies

No dependencies set.

Reference: starred/terminal#29008
Delete Branch "%!s()"

Deleting a branch is permanent. Although the deleted branch may continue to exist for a short time before it actually gets removed, it CANNOT be undone in most cases. Continue?