Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table #9213

vicliu624 · 2026-01-07T16:13:20Z

Summary

Enable Chinese display and IME on T-Deck (LCD) and refine IME behavior/UX for T-Deck Pro.

Changes

Enable U8g2 text rendering on T-Deck (LCD) and use GB2312-capable font for Chinese display.
Add/enable Chinese IME for T-Deck (alongside T-Deck Pro) and keep IME disabled by default until CN mode is selected.
Gate IME paging to active candidate sessions; reset/disable IME on exit from freetext.
Adjust IME candidate bar position upward to avoid footer overlap.
Insert space directly when CN mode is active but IME buffer is empty.
Harden UTF‑8 apostrophe normalization with bounds checks.
Pin U8g2_for_Adafruit_GFX to an immutable commit SHA (both t-deck / t-deck-pro).

Testing

Built on T-Deck (ESP32-S3)
Built on T-Deck Pro (ESP32-S3)

Notes

IME is only active in CN mode; other modes remain EN/123.
IME buffer is cleared and disabled when leaving freetext.

🤝 Attestations

I have tested that my proposed changes behave as described.
I have tested that my proposed changes do not cause any obvious regressions on the following devices:
- Heltec (Lora32) V3
- LilyGo T-Deck
- LilyGo T-Beam
- RAK WisBlock 4631
- Seeed Studio T-1000E tracker card
- Other (please specify below)

Other:

LilyGo T-Deck Pro (ESP32-S3)

- embed pinyin table as PROGMEM data guarded by T_DECK_PRO - trim dictionary to GB2312-encodable characters to fit flash - disable IME paths on non?T-Deck Pro targets - keep candidate matching and selection logic unchanged

CLAassistant · 2026-01-07T16:13:26Z

All committers have signed the CLA.

github-actions · 2026-01-07T16:13:42Z

@vicliu624, Welcome to Meshtastic!

Thanks for opening your first pull request. We really appreciate it.

We discuss work as a team in discord, please join us in the #firmware channel.
There's a big backlog of patches at the moment. If you have time,
please help us with some code review and testing of other PRs!

Welcome to the team 😄

- guard pgmspace include behind T_DECK_PRO - skip builtin dictionary parsing when IME is disabled

- default IME mode to EN and reset state on freetext entry - gate CN mode by region and map 123 input to numbers/symbols - count remaining chars by byte budget in freetext UI - fix right alignment for mixed ASCII/CJK lines

Copilot

Pull request overview

This PR adds a Chinese Input Method Editor (IME) for the T-Deck Pro device with a built-in GB2312-tuned pinyin dictionary. The implementation includes support for rendering CJK text using the U8g2 font library and improves message editor UX with UTF-8-aware cursor navigation and character counting.

Key changes:

Embeds a ~42KB pinyin dictionary as PROGMEM data (T_DECK_PRO only)
Adds Chinese IME class with candidate selection and pinyin-to-character conversion
Integrates U8g2_for_Adafruit_GFX library for CJK font rendering
Implements three input modes (CN/EN/123) with mode cycling via Fn/Symbol key
Adds UTF-8 aware text navigation and byte-based character counting
Fixes text alignment for mixed ASCII/CJK content in message rendering

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
variants/esp32s3/t-deck-pro/platformio.ini	Adds U8g2_for_Adafruit_GFX library dependency and USE_U8G2_EINK_TEXT build flag
src/modules/PinyinData.h	Embeds GB2312 pinyin dictionary as PROGMEM for T_DECK_PRO builds
src/modules/ChineseIme.h	Defines IME interface with candidate management and buffer operations
src/modules/ChineseIme.cpp	Implements IME logic including candidate lookup from embedded dictionary
src/modules/CannedMessageModule.h	Adds IME state variables and mode enum for message editor integration
src/modules/CannedMessageModule.cpp	Integrates IME with freetext editor, adds UTF-8 navigation helpers and rendering
src/input/kbI2cBase.cpp	Adds handling for new IME control key events
src/input/TDeckProKeyboard.cpp	Generates IME page navigation events on shift key press
src/input/InputBroker.h	Defines new input event codes for IME control
src/graphics/draw/MessageRenderer.cpp	Updates text rendering to use U8g2 fonts for CJK characters
src/graphics/EInkDisplay2.h	Declares U8g2 font adapter interface
src/graphics/EInkDisplay2.cpp	Implements U8g2 bridge to OLEDDisplay buffer
src/graphics/Screen.cpp	Adds debug logging for UI frame events

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Copilot · 2026-01-08T06:23:23Z

src/graphics/draw/MessageRenderer.cpp

+        size_t len = utf8CharLen(c);
+
+        // Normalize fancy apostrophe to ASCII
+        if (c == 0xE2 && (uint8_t)messageBuf[i + 1] == 0x80 && (uint8_t)messageBuf[i + 2] == 0x99) {


The code at line 846 checks messageBuf[i + 1] and messageBuf[i + 2] without verifying that these indices are within bounds. If messageBuf[i] is 0xE2 but the string is truncated (ending at i+1 or i+2), this will read beyond the null terminator, potentially accessing invalid memory. Add bounds checks before accessing messageBuf[i + 1] and messageBuf[i + 2].

Copilot · 2026-01-08T06:23:23Z

src/modules/ChineseIme.cpp

+            while (*p && *p != ' ')
+                ++p;
+            if (p > start)
+                appendCandidate(list, String(start).substring(0, p - start));


This line creates a String from a pointer range and then calls substring(0, p - start) on it. However, the String constructor creates a String from the entire null-terminated string at start, not just the characters from start to p. This means if there are characters beyond position p, the substring call is needed, but if the String constructor only reads up to a space or null, the substring might be redundant or incorrect. Consider using String(start, p - start) constructor instead to directly create a string of the correct length without the intermediate substring call.

Suggested change

appendCandidate(list, String(start).substring(0, p - start));

appendCandidate(list, String(start, p - start));

Copilot · 2026-01-08T06:23:24Z

src/input/TDeckProKeyboard.cpp

+        queueEvent(INPUT_BROKER_MSG_IME_PAGE_NEXT);
    } else if (key == modifierLeftShiftKey) {
        modifierFlag ^= modifierLeftShift;
+        queueEvent(INPUT_BROKER_MSG_IME_PAGE_PREV);


The updateModifierFlag function queues IME page navigation events (INPUT_BROKER_MSG_IME_PAGE_NEXT and INPUT_BROKER_MSG_IME_PAGE_PREV) every time the shift keys are pressed, regardless of whether IME is active or enabled. This will cause these events to be sent even when the user is not in freetext mode or when Chinese IME is disabled. Consider adding a conditional check to only queue these events when the IME is active and has candidates to navigate.

Suggested change

queueEvent(INPUT_BROKER_MSG_IME_PAGE_NEXT);

} else if (key == modifierLeftShiftKey) {

modifierFlag ^= modifierLeftShift;

queueEvent(INPUT_BROKER_MSG_IME_PAGE_PREV);

if (InputBroker::instance().isImeActive() && InputBroker::instance().hasImeCandidates()) {

queueEvent(INPUT_BROKER_MSG_IME_PAGE_NEXT);

}

} else if (key == modifierLeftShiftKey) {

modifierFlag ^= modifierLeftShift;

if (InputBroker::instance().isImeActive() && InputBroker::instance().hasImeCandidates()) {

queueEvent(INPUT_BROKER_MSG_IME_PAGE_PREV);

}

Copilot · 2026-01-08T06:23:25Z

src/modules/CannedMessageModule.cpp

+                    runOnce();
+                    return true;
+                }
+            }


When IME buffer is empty and space is pressed while in CN mode, this code doesn't handle the space character and the function continues to line 1291 where it may be treated as a regular printable character in NUM mode. This means that if a user is in CN mode with an empty IME buffer and presses space, it could be transformed by mapNumModeChar instead of being inserted as a space. Consider either inserting a space when IME buffer is empty and space is pressed, or ensuring the logic falls through correctly.

Suggested change

}

}

} else if (event->kbchar == ' ') {

// IME buffer is empty in CN mode: insert a space directly instead of

// falling through to generic printable handling (which may apply NUM mapping).

payload = ' ';

lastTouchMillis = millis();

runOnce();

return true;

Copilot · 2026-01-08T06:23:26Z

src/modules/ChineseIme.h

+    bool enabled =
+#if defined(T_DECK_PRO)
+        true;
+#else
+        false;
+#endif


The ChineseIme class defaults to enabled=true for T_DECK_PRO builds. However, according to the PR description, the IME should be disabled by default and only enabled when in CN mode (which is only available when region=CN). This conflicts with the initialization in LaunchFreetextWithDestination where imeMode is set to EN and ime.setEnabled(false) is called. The default should be false to avoid confusion and ensure consistency with the intended behavior.

Suggested change

bool enabled =

#if defined(T_DECK_PRO)

true;

#else

false;

#endif

bool enabled = false;

Copilot · 2026-01-08T06:23:26Z

variants/esp32s3/t-deck-pro/platformio.ini

+  # renovate: datasource=github-tags depName=U8g2_for_Adafruit_GFX packageName=olikraus/U8g2_for_Adafruit_GFX
+  https://github.com/olikraus/U8g2_for_Adafruit_GFX/archive/refs/tags/1.8.0.zip


The new lib_deps entry pulls U8g2_for_Adafruit_GFX directly from a GitHub tag ZIP (.../refs/tags/1.8.0.zip), which is a mutable reference with no integrity verification. If the upstream repository or tag were compromised or force-moved, future builds could silently consume attacker-controlled code and ship compromised firmware. To reduce supply-chain risk, pin this dependency to an immutable commit (or a verified release in the PlatformIO registry) and/or add an integrity check (hash/signature) for the downloaded artifact.

- Gate IME paging to active candidate sessions and reset/disable IME on exit - Lift IME candidate bar to avoid footer overlap - Insert space in CN mode when buffer is empty - Harden UTF-8 apostrophe normalization bounds checks - Pin U8g2_for_Adafruit_GFX to an immutable commit SHA

Xaositek

I want to be cautious of changing the font size in messages themselves. This should be uniform with the text size as the time / node info.

Xaositek · 2026-01-09T13:36:26Z

src/graphics/draw/MessageRenderer.cpp

+#if defined(USE_U8G2_EINK_TEXT)
+    if (auto *u8g2 = getU8g2Fonts(display)) {
+        const int baseline = y + FONT_HEIGHT_SMALL - 1;
+        u8g2->drawUTF8(x, baseline, text.c_str());


In testing this it appears the font or font size has changed? Message fonts are much smaller now.

vicliu624 added 2 commits January 7, 2026 19:46

feature: properly render received Chinese characters on T-Deck Pro

dada1db

Add Chinese IME with GB2312-tuned dictionary for T-Deck Pro

011e93d

- embed pinyin table as PROGMEM data guarded by T_DECK_PRO - trim dictionary to GB2312-encodable characters to fit flash - disable IME paths on non?T-Deck Pro targets - keep candidate matching and selection logic unchanged

github-actions bot added the first-contribution label Jan 7, 2026

vicliu624 changed the title ~~Feature unicode cjk for t deck pro~~ Feature T-Deck Pro: add Chinese IME and built-in GB2312 pinyin table Jan 7, 2026

vicliu624 added 2 commits January 8, 2026 00:22

Fix IME build on non?T-Deck Pro targets

cc2571d

- guard pgmspace include behind T_DECK_PRO - skip builtin dictionary parsing when IME is disabled

Refine IME defaults and message rendering alignment

f3058a7

- default IME mode to EN and reset state on freetext entry - gate CN mode by region and map 123 input to numbers/symbols - count remaining chars by byte budget in freetext UI - fix right alignment for mixed ASCII/CJK lines

fifieldt added the enhancement New feature or request label Jan 8, 2026

fifieldt requested review from Xaositek and Copilot January 8, 2026 06:13

Copilot started reviewing on behalf of fifieldt January 8, 2026 06:18 View session

Copilot AI reviewed Jan 8, 2026

View reviewed changes

vicliu624 changed the title ~~Feature T-Deck Pro: add Chinese IME and built-in GB2312 pinyin table~~ Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table Jan 8, 2026

Xaositek requested changes Jan 9, 2026

View reviewed changes

Align U8g2 text sizing and decouple IME flags

38063dd

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Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table #9213

Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table #9213

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	appendCandidate(list, String(start).substring(0, p - start));
	appendCandidate(list, String(start, p - start));

-            }
+            }
+        } else if (event->kbchar == ' ') {
+            // IME buffer is empty in CN mode: insert a space directly instead of
+            // falling through to generic printable handling (which may apply NUM mapping).
+            payload = ' ';
+            lastTouchMillis = millis();
+            runOnce();
+            return true;

		# renovate: datasource=github-tags depName=U8g2_for_Adafruit_GFX packageName=olikraus/U8g2_for_Adafruit_GFX
		https://github.com/olikraus/U8g2_for_Adafruit_GFX/archive/refs/tags/1.8.0.zip

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Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table #9213

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Feature T-Deck Pro and T-Deck: add Chinese IME and built-in GB2312 pinyin table #9213

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Summary

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Testing

Notes

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github-actions bot commented Jan 7, 2026

@vicliu624, Welcome to Meshtastic!

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vicliu624 commented Jan 7, 2026 •

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