56 lines
3.2 KiB
Markdown
56 lines
3.2 KiB
Markdown
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# Flash Size Optimization: Per-Family Font and Per-Language Hyphenation Flags
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**Date**: 2026-02-15
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## Task Description
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Investigated ESP32-C3 flash usage (97.3% full at 6.375 MB / 6.5 MB app partition) and implemented build flags to selectively exclude font families and hyphenation language tries. Fonts alone consumed 65.6% of flash (3.99 MB).
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## Changes Made
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### 1. `lib/EpdFont/builtinFonts/all.h`
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- Wrapped Bookerly includes (16 files) in `#ifndef OMIT_BOOKERLY`
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- Wrapped Noto Sans 12-18pt includes (16 files) in `#ifndef OMIT_NOTOSANS` (kept `notosans_8_regular.h` outside guard for UI small font)
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- Wrapped OpenDyslexic includes (16 files) in `#ifndef OMIT_OPENDYSLEXIC`
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### 2. `src/main.cpp`
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- Wrapped Bookerly 14pt font objects (previously always included) in `#ifndef OMIT_BOOKERLY`
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- Added per-family `#ifndef OMIT_*` guards inside the existing `#ifndef OMIT_FONTS` block for other sizes
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- Added matching guards to font registration in `setupDisplayAndFonts()`
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### 3. `src/SettingsList.h`
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- Added `FontFamilyMapping` struct and `kFontFamilyMappings[]` compile-time table with per-family `#ifndef` guards
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- Switched Font Family setting from `SettingInfo::Enum` to `SettingInfo::DynamicEnum` with getter/setter that maps between list indices and fixed enum values (BOOKERLY=0, NOTOSANS=1, OPENDYSLEXIC=2)
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- Added `static_assert` ensuring at least one font family is available
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### 4. `src/activities/settings/SettingsActivity.cpp`
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- Added DynamicEnum toggle support in `toggleCurrentSetting()` (cycles through options via `valueGetter`/`valueSetter`)
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- Added DynamicEnum display support in `render()` display lambda
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### 5. `src/CrossPointSettings.cpp`
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- Guarded `getReaderFontId()` switch cases with `#ifndef OMIT_*`, added `default:` fallback to first available font
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- Guarded `getReaderLineCompression()` switch cases with `#ifndef OMIT_*`, added `default:` fallback
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- Added `#error` directive if all font families are omitted
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### 6. `lib/Epub/Epub/hyphenation/LanguageRegistry.cpp`
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- Added per-language `#ifndef OMIT_HYPH_xx` guards around includes, `LanguageHyphenator` objects, and entries
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- Switched from `std::array<LanguageEntry, 6>` to `std::vector<LanguageEntry>` for variable entry count
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- Languages: DE (201 KB), EN (27 KB), ES (13 KB), FR (7 KB), IT (2 KB), RU (33 KB)
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### 7. `platformio.ini`
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- Added to `[env:mod]`: `-DOMIT_OPENDYSLEXIC`, `-DOMIT_HYPH_DE`, `-DOMIT_HYPH_EN`, `-DOMIT_HYPH_ES`, `-DOMIT_HYPH_FR`, `-DOMIT_HYPH_IT`, `-DOMIT_HYPH_RU`
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## Design Decisions
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- Enum values stay fixed (BOOKERLY=0, NOTOSANS=1, OPENDYSLEXIC=2) for settings file compatibility
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- Existing `OMIT_FONTS` flag left untouched; per-family flags nest inside it
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- DynamicEnum used for Font Family to handle index-to-value mapping when fonts are removed from the middle of the options list
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## Estimated Savings (mod build)
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- OpenDyslexic fonts: ~1,052 KB
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- All hyphenation tries: ~282 KB
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- **Total: ~1,334 KB (~1.30 MB)** -- from 97.3% down to ~76.9%
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## Follow-up Items
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- Build and verify the `mod` environment compiles cleanly and flash size reduction matches estimates
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- Other available flags for future use: `OMIT_BOOKERLY`, `OMIT_NOTOSANS` (individual language OMIT_HYPH_xx flags can also be used selectively)
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