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Ken Van Hoeylandt db48dfe812 Fixes and improvements (#620 )

- Standardized keyboard input using Unicode-based key codes across supported devices and the simulator. Keyboards don't emit `LV_KEY_*` anymore.
- Refactored lilygo encoder driver into a reusable GPIO rotary encoder driver (see `Drivers/gpio-encoder-module/`). Added more features to the config file.
- Improved LVGL keyboard device management, including duplicate prevention and reliable reconnects.
- LVGL file mutex now registers with lvgl start/stop
- Improved LVGL startup/shutdown stability and memory allocation reliability.
- Increased simulator LVGL memory capacity and improved USB device-class handling.

2026-08-23 17:21:16 +02:00

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lvgl-module

This module manages the lifecycle of the LVGL library within the Tactility ecosystem.

What the library does

The lvgl-module provides:

Lifecycle Management: Handles initialization and termination of the LVGL library.
Task Management: Manages the LVGL main loop task.
Thread-Safety: Provides mutex-based locking mechanisms (lvgl_lock, lvgl_unlock) to ensure safe access to LVGL APIs from multiple tasks.
Font Access: Provides a unified interface to access pre-configured text and icon fonts.

Different types of fonts

The module supports two main categories of fonts:

Text Fonts

Standard text rendering uses the Montserrat font. Three sizes are pre-configured:

FONT_SIZE_SMALL
FONT_SIZE_DEFAULT
FONT_SIZE_LARGE

Icon Fonts

Icons are provided by the Material Symbols font, divided into three usage-specific sets:

Statusbar Icons: Optimized for the system status bar.
Launcher Icons: Sized for application launchers.
Shared Icons: General purpose icons used across the system.

How to update the fonts

Font sizes and symbols are configurable:

On ESP32 (IDF): Sizes can be updated via menuconfig or by editing sdkconfig. Look for CONFIG_TT_LVGL_FONT_SIZE_* and CONFIG_TT_LVGL_*_ICON_SIZE parameters.
On Simulator/POSIX: Default sizes are defined in Modules/lvgl-module/CMakeLists.txt.

If you change an icon font size, ensure that a corresponding C file exists in source-fonts/ (e.g., material_symbols_shared_24.c). These files are generated from TTF/OTF fonts using the LVGL font converter.

Custom memory allocator

LVGL's malloc/realloc/free can be routed through a custom backend instead of its built-in pool or plain malloc. Three things are required:

1. Select the backend. On ESP32, via Kconfig (sdkconfig):

CONFIG_LV_USE_CUSTOM_MALLOC=y

On Simulator/POSIX, ESP-IDF's Kconfig doesn't apply - select it in lv_conf.h instead:

#define LV_USE_STDLIB_MALLOC LV_STDLIB_CUSTOM

2. Force the module into the link. LVGL's own init code calls back into the functions above a reverse reference a normal single-pass static-archive link can't resolve on its own:

tactility_add_module(lvgl-module
    ...
    WHOLE_ARCHIVE
)

Without WHOLE_ARCHIVE, or without step 1 selecting the custom backend, ESP-IDF's LVGL component compiles its own allocator using these same symbol names - whichever one the linker happens to pull in first silently wins, with no error and no guarantee it's the intended one.

License

This module is licensed under the Apache v2.0 license.

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