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Fix microsoft ime input #1058

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Fix microsoft ime input #1058

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1cb50d7
fix: Handle Microsoft IME issue with Shift key detection
0141KoppePan Dec 10, 2025
2b0dc2c
fix: Microsoft IME keydown handling for Zenkaku/Hankaku keys
0141KoppePan Dec 10, 2025
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40 changes: 29 additions & 11 deletions ui/src/components/WebRTCVideo.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -260,6 +260,9 @@ export default function WebRTCVideo({ hasConnectionIssues }: { hasConnectionIssu
code = "Henkan";
} else if (code === "NonConvert") {
code = "Muhenkan";
// Microsoft IME fix
} else if (key === "Shift" && code === "") {
code = "ShiftRight"
}

return code;
Expand Down Expand Up @@ -303,6 +306,13 @@ export default function WebRTCVideo({ hasConnectionIssues }: { hasConnectionIssu
altGrLoopRef.current = true;
lastKeyDownRef.current = null;
}

// Microsoft IME fix:
// Effective keydown events are consumed by IME (reported as "Process"),
// so we handle the full press/release cycle in the keyup handler instead.
if (["Zenkaku", "Hankaku", "ZenkakuHankaku"].includes(e.key)) {
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@IDisposable IDisposable Dec 11, 2025

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Do we want to ignore them here only on isWindowClient condition?

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@0141KoppePan 0141KoppePan Dec 11, 2025 •
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The IME keydown bypass is currently placed inside the isWindowsClient condition, so this logic runs only on Windows.
Since Windows is the only platform I can reliably test at the moment, I would prefer to keep this PR Windows-only for now.

However, I also have access to Linux and macOS, so I can follow up with a separate PR to address non-Windows IME behavior as well.

For reference, here is what I have observed so far:

  • On Linux (Ubuntu 25.10 + Mozc Japanese input method), pressing the Hankaku/Zenkaku key emits only a keyup event.
  • On macOS, the Hankaku/Zenkaku key is not used. Instead, 英数 (key: Eisu, code: Lang2) and かな (key: KanjiMode, code: Lang1) are used — and both produce only keyup events as well.

Figure 1. Linux(ubuntu + mozc) Keyboard Event
image

Figure 2. macOS Keyboard Event
image

Figure 3. Mac Keyboard(JIS) 英数 and かな keys
image

I will verify these behaviors more thoroughly and submit an additional PR to handle Linux and macOS explicitly.

return;
}
}

// When pressing the meta key + another key, the key will never trigger a keyup
Expand Down Expand Up @@ -342,21 +352,29 @@ export default function WebRTCVideo({ hasConnectionIssues }: { hasConnectionIssu
return;
}

// On Windows, handle ControlLeft specially to preserve FIFO semantics with AltGr buffering.
if (isWindowsClient && hidKey === keys.ControlLeft) {
if (isWindowsClient) {
// On Windows, handle ControlLeft specially to preserve FIFO semantics with AltGr buffering.
if (hidKey === keys.ControlLeft) {
// Synthetic AltGr ControlLeft: never sent a down, swallow the release as well.
if (altGrLoopRef.current) {
altGrLoopRef.current = false;
return;
}

// Synthetic AltGr ControlLeft: never sent a down, swallow the release as well.
if (altGrLoopRef.current) {
altGrLoopRef.current = false;
return;
}
// Very fast real Ctrl tap: flush the pending down before the up.
if (lastKeyDownRef.current?.hidKey === keys.ControlLeft) {
handleKeyPress(keys.ControlLeft, true);
}

// Very fast real Ctrl tap: flush the pending down before the up.
if (lastKeyDownRef.current?.hidKey === keys.ControlLeft) {
handleKeyPress(keys.ControlLeft, true);
lastKeyDownRef.current = null;
}

lastKeyDownRef.current = null;
// Microsoft IME fix:
// Synthesize the missing keydown event to ensure a complete key press cycle.
if (["Zenkaku", "Hankaku", "ZenkakuHankaku"].includes(e.key)) {
console.debug(`Synthesizing missed key down for IME key: ${e.key}`);
handleKeyPress(hidKey, true);
}
}

console.debug(`Key up: ${hidKey}`);
Expand Down