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**Fonts** Dynamically load text and icon fonts when the device boots. Font bitdepth depends on whether the device is an ESP32 one and whether it has external RAM available. When no external RAM is available on ESP32, only small and medium font variants are generated; large font variants refer to the medium size ones. Implemented Appearance settings app for changing font and font size. **Other changes** - Added keyboard shortcuts to delete or rename files in directory views. - Improved app-grid tile sizing to provide more room for labels. - Reduced the default LED strip brightness.
73 lines
3.2 KiB
Markdown
73 lines
3.2 KiB
Markdown
# lvgl-module
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This module manages the lifecycle of the [LVGL](https://lvgl.io/) library within the Tactility ecosystem.
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## What the library does
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The `lvgl-module` provides:
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- **Lifecycle Management**: Handles initialization and termination of the LVGL library.
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- **Task Management**: Manages the LVGL main loop task.
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- **Thread-Safety**: Provides mutex-based locking mechanisms (`lvgl_lock`, `lvgl_unlock`) to ensure safe access to LVGL APIs from multiple tasks.
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- **Font Access**: Provides a unified interface to access pre-configured text and icon fonts.
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## Different types of fonts
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The module supports two main categories of fonts:
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### Text Fonts
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Text uses the **Adwaita Sans** font in three sizes:
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- `FONT_SIZE_SMALL`
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- `FONT_SIZE_DEFAULT`
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- `FONT_SIZE_LARGE`
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Until Tactility registers these fonts with `lvgl_set_text_font()`, the getters return LVGL's built-in default font (Montserrat).
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### Icon Fonts
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Icons are provided by the **Material Symbols** font, divided into three usage-specific sets:
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- **Statusbar Icons**: Optimized for the system status bar.
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- **Launcher Icons**: Sized for application launchers.
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- **Shared Icons**: General purpose icons used across the system.
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## How to update the fonts
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All font sizes derive from one default text size: `font.defaultSize` in `device.properties` (`CONFIG_TT_FONT_DEFAULT_SIZE`, 14 on the simulator).
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Tactility calculates the other text and icon sizes from it in `Tactility/Source/lvgl/FontSizes.cpp`.
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Text fonts are rasterized on device at startup from `Data/system/fonts/AdwaitaSans.ttf` and cached as `.bin` files in the data path.
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`Tactility/Fonts/generate.py` creates that TTF subset from `Tactility/Fonts/AdwaitaSans-Regular.ttf` (requires `pip install fonttools`).
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Icon fonts are rasterized on device at startup from `Data/system/fonts/MaterialSymbolsRounded.ttf` (a subset with only the used icons) and cached as `.bin` files in the data path, so any icon size works.
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The icons per font are listed by name and resolved through `Data/system/fonts/MaterialSymbolsRounded.codepoints`.
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To add an icon, add its name to `generate-icons.py` and run it (requires `pip install fonttools`). This regenerates the TTF subset, the codepoints file and the name lists.
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## Custom memory allocator
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LVGL's malloc/realloc/free can be routed through a custom backend instead of its built-in pool or
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plain `malloc`. Three things are required:
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**1. Select the backend.** On ESP32, via Kconfig (`sdkconfig`):
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```sdkconfig
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CONFIG_LV_USE_CUSTOM_MALLOC=y
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```
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On Simulator/POSIX, ESP-IDF's Kconfig doesn't apply - select it in `lv_conf.h` instead:
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```c
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#define LV_USE_STDLIB_MALLOC LV_STDLIB_CUSTOM
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```
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**2. Force the module into the link.** LVGL's own init code calls back into the functions above
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a reverse reference a normal single-pass static-archive link can't resolve on its own:
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```cmake
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tactility_add_module(lvgl-module
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...
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WHOLE_ARCHIVE
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)
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```
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Without `WHOLE_ARCHIVE`, or without step 1 selecting the custom backend, ESP-IDF's LVGL component
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compiles its own allocator using these same symbol names - whichever one the linker happens to
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pull in first silently wins, with no error and no guarantee it's the intended one.
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## License
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This module is licensed under the [Apache v2.0](LICENSE-Apache-2.0.md) license. |