Move all blink handling into Renderer by lhecker · Pull Request #19330 · microsoft/terminal

lhecker · 2025-09-08T19:39:36Z

This PR moves the cursor blinker and VT blink rendition timer into
Renderer. To do so, this PR introduces a generic timer system with
which you can schedule arbitrary timer jobs. Thanks to this, this PR
removes a crapton of code, particularly throughout conhost.

Validation Steps Performed

Focus/unfocus starts/stops blinking ✅
OS-wide blink settings apply on focus ✅

src/interactivity/win32/AccessibilityNotifier.cpp

src/renderer/base/renderer.cpp

Goal: Remove `CursorBlinker`. Problem: Spooky action at a distance via `Cursor::HasMoved`. Solution: Moved all the a11y event raising into `_stream.cpp` and pray for the best. Goal: Prevent node.js from tanking conhost performance via MSAA (WHY). Problem: `ServiceLocator`. Solution: Unserviced the locator. Debounced event raising. Performance increased by >10x. Problem 2: Lots of files changed. This PR is a prerequisite for #19330 ## Validation Steps Performed Ran NVDA with and without UIA enabled and with different delays. ✅

src/cascadia/TerminalControl/HwndTerminal.hpp

src/cascadia/TerminalControl/HwndTerminal.cpp

src/renderer/base/renderer.cpp

src/host/renderData.cpp

src/host/output.cpp

src/terminal/adapter/adaptDispatch.cpp

DHowett

50/56

src/renderer/base/lib/base.vcxproj.filters

DHowett · 2025-09-26T20:45:26Z

src/interactivity/win32/window.cpp

 // - <none>
 // Return Value:
 // - <none>
 void Window::_UpdateSystemMetrics() const


📝 Make sure nobody else called this who cares about the cursor metrics (probably not)

DHowett · 2025-09-26T20:46:32Z

src/host/selectionState.cpp

    cursor.SetSize(_d->ulSavedCursorSize);
    cursor.SetIsVisible(_d->fSavedCursorVisible);
    cursor.SetType(_d->savedCursorType);
-    cursor.SetIsOn(true);


📝 make sure selection has the same cursor behavior

src/host/renderData.cpp

src/host/output.cpp

src/host/AccessibilityNotifier.cpp

src/cascadia/TerminalCore/TerminalSelection.cpp

src/cascadia/TerminalCore/Terminal.cpp

src/cascadia/TerminalControl/TermControl.cpp

…inker

src/buffer/out/cursor.cpp

carlos-zamora · 2025-11-04T21:28:34Z

src/cascadia/TerminalControl/TermControl.cpp

+
    void TermControl::CursorVisibility(Control::CursorDisplayState cursorVisibility)
    {
        _cursorVisibility = cursorVisibility;


It looks like cursor visibility is stored across 3 variables:

TermControl::_cursorVisibility

ControlCore::_forceCursorVisible

Renderer::_cursorVisibilityInhibitors

Could we remove the one in TermControl and just query the one in ControlCore? Or, even better, just pipe the value from Renderer all the way up, rather than having a separate boolean member on each layer?

I actually tried this, but that doesn't work unless we refactor how focus is handled in ControlInteractivity. This is because we make a distinction in TermControl between cursor-visible-because-of-xaml-focus and cursor-visible-because-of-cursor-display-state. ControlCore then ties these together into a single boolean again, with some extra logic on top. If you ask me, it's a mistake to handle XAML/UI-logic in the ControlCore layer like that. It should just be "do I have focus? yes/no" and TermControl decides that.

I would not expose _forceCursorVisible from ControlCore just to remove the _cursorVisibility in TermControl. The variables are duplicated now, but they serve a different purpose. It'd be better to remove the need for forcing the cursor visibility in the first place IMO.

src/cascadia/TerminalCore/Terminal.cpp

src/cascadia/TerminalSettingsEditor/Profiles_Appearance.cpp

carlos-zamora · 2025-11-04T22:38:19Z

src/renderer/base/renderer.hpp

+        static DWORD _timerToMillis(TimerRepr t) noexcept;
+
+        // Actual rendering
+        [[nodiscard]] HRESULT PaintFrame();


It's a bit weird that this one is marked private, but doesn't have the _ prefix. Plus there's also _PaintFrame() just below it.

IIRC I did this to help git with reducing the diff size.

src/host/selection.cpp

carlos-zamora · 2025-11-04T23:41:04Z

Fully reviewed. I want to get some resolution on my comments before approving.

Regarding accessibility (#19374), I plan on taking a look at a reported memory leak in WT when UIA is enabled soon-ish. I'll lump looking into #19374 too and Leonard and I can tag team work on a11y then.

carlos-zamora · 2025-11-04T23:42:04Z

Oh, and you probably want to update the PR body too.

carlos-zamora

LGTM. Thanks for doing this 🙂

lhecker · 2025-11-11T14:30:06Z

I've merged this now @DHowett so we can move on and fix it in post if needed.

DHowett · 2025-11-11T21:12:56Z

src/renderer/base/renderer.cpp

+        }
+    }
+
+why_does_cpp_not_have_labeled_loops:


DHowett

approved 63/63 after merge. Well done. One nit: StarTimer ⭐

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lhecker force-pushed the dev/lhecker/cursor-blinker branch from 4de989d to 8d17e85 Compare September 8, 2025 19:44

lhecker mentioned this pull request Sep 12, 2025

Rewrite the MSAA/UIA integration into conhost #19344

Merged

lhecker changed the base branch from main to dev/lhecker/BEGONE-FOUL-SPIRIT September 14, 2025 11:16

lhecker force-pushed the dev/lhecker/cursor-blinker branch from 8d17e85 to 8390d60 Compare September 14, 2025 11:26

lhecker force-pushed the dev/lhecker/cursor-blinker branch from 8390d60 to 5742c64 Compare September 22, 2025 22:59

lhecker changed the base branch from dev/lhecker/BEGONE-FOUL-SPIRIT to main September 22, 2025 22:59

lhecker marked this pull request as ready for review September 22, 2025 22:59

Move all blink handling into Renderer

1c23430

lhecker force-pushed the dev/lhecker/cursor-blinker branch from 5742c64 to 1c23430 Compare September 23, 2025 13:55

lhecker mentioned this pull request Sep 23, 2025

WPF terminal control in a tabbed interface deadlocks when rapidly opening new tabs #19373

Open

Fix tests?

1b712b2

carlos-zamora reviewed Sep 23, 2025

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Fix tests

1c07227

DHowett reviewed Sep 26, 2025

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lhecker added 6 commits October 14, 2025 18:37

Merge remote-tracking branch 'origin/main' into dev/lhecker/cursor-bl…

0ff1f1f

…inker

Fix off-by-one bugs

7083bc0

Add support for EVENT_CONSOLE_UPDATE_SIMPLE

8214051

Fix build

55e3efe

Address feedback, Fix broadcast input

dfad2d9

Fix assert

99c6193

carlos-zamora reviewed Nov 4, 2025

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carlos-zamora approved these changes Nov 6, 2025

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lhecker merged commit 2e78665 into main Nov 11, 2025
19 checks passed

DHowett reviewed Nov 11, 2025

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src/renderer/base/renderer.cpp

}

}

why_does_cpp_not_have_labeled_loops:

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lol

DHowett reviewed Nov 11, 2025

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DHowett deleted the dev/lhecker/cursor-blinker branch November 20, 2025 19:45

DHowett mentioned this pull request Jan 12, 2026

[1.25] Preview Terminal in settings UI does not show cursor any longer #19735

Closed

lhecker mentioned this pull request Jan 19, 2026

Reduce input latency with double buffering #19757

Closed

4 tasks

DHowett mentioned this pull request Jan 23, 2026

Continue SGR 5 blinking when Terminal is out of focus (but not minimized) #19524

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lhecker commented Sep 8, 2025 •

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