## Summary
**What is the goal of this PR?**
Update SKILL.md to stop instructing contributors to commit `I18nKeys.h`
and `I18nStrings.h`. All three generated i18n files have been gitignored
since ff577540 and are regenerated at build time.
---
### AI Usage
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## Summary
**What is the goal of this PR?**
Until today, I sincerely thought we were building without exception
support. The codebase is not set up with any exception handling
infrastructure. The SKILL.md file specifies no exceptions.
I just learned that we actually were building with exceptions enabled,
with `-fexceptions` coming from
~/.platformio/packages/framework-arduinoespressif32-libs/esp32c3/pioarduino-build.py.
This change removes the `-fexceptions` flag and adds `-fno-exceptions`.
The result is **53,670 bytes in flash savings**.
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## Summary
**What is the goal of this PR?**
### Problem
Inter-word gap widths were computed as two separately-snapped integers:
```cpp
gap = getSpaceWidth(fontId, style); // fp4::toPixel(spaceAdvance)
gap += getSpaceKernAdjust(fontId, leftCp, rightCp, style); // fp4::toPixel(kern1 + kern2)
```
Because `fp4::toPixel(a) + fp4::toPixel(b)` can differ from
`fp4::toPixel(a + b)` by +/-1 pixel when the fractional parts straddle a
rounding boundary, each inter-word space could be one pixel wider or
narrower than the correct value. This affected line-break width
decisions and word-position accumulation across the whole paragraph
layout pipeline.
### Fix
Replaces `getSpaceKernAdjust()` with `getSpaceAdvance(fontId, leftCp,
rightCp, style)`, which combines the space glyph advance and both
flanking kern values (`kern(leftCp, ' ')` + `kern(' ', rightCp)`) into a
single fixed-point sum before the snap:
```cpp
return fp4::toPixel(spaceAdvanceFP + kern(leftCp, ' ') + kern(' ', rightCp));
```
This is the same single-snap pattern already used by `getTextAdvanceX`
for word widths.
### Changes
- **`GfxRenderer`**: Replaces `getSpaceKernAdjust()` with
`getSpaceAdvance()`. `getSpaceWidth()` is retained for the
single-space-word case in `measureWordWidth` where no adjacent-word kern
context is available.
- **`ParsedText`**: All four call sites (`computeLineBreaks`,
`computeHyphenatedLineBreaks`, and both loops in `extractLine`) updated
to use `getSpaceAdvance()`. The now-redundant `spaceWidth`
pre-computation and parameter are removed from all three internal layout
functions.
---
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correctness**_
## Summary
**What is the goal of this PR?**
This change avoids the pattern of creating a `std::string` using
`.substr` in order to compare against a file extension literal.
```c++
std::string path;
if (path.length() >= 4 && path.substr(path.length() - 4) == ".ext")
```
The `checkFileExtension` utility has moved from StringUtils to
FsHelpers, to be available to code in lib/. The signature now accepts a
`std::string_view` instead of `std::string`, which makes the single
implementation reusable for Arduino `String`.
Added utility functions for commonly repeated extensions.
These changes **save about 2 KB of flash (5,999,427 to 5,997,343)**.
---
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## Summary
**What is the goal of this PR?**
Quick follow up to #1291, adding Polish translations suggested by
@th0m4sek
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## Summary
**What is the goal of this PR?**
Avoid building cache path strings twice, once to check existence of the
file and a second time to delete the file.
---
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## Summary
**What is the goal of this PR?**
Hopefully fixes#1182.
_Note: I think letterforms got a "heavier" appearance after #1098, which
makes this more noticeable. The current version of this PR reverts the
change to add `--force-autohint` for Bookerly, which to me seems to
bring the font back to a more aesthetic and consistent weight._
#### Problem
Character spacing was uneven in certain words. The word "drew" in
Bookerly was the clearest example: a visible gap between `d` and `r`,
while `e` and `w` appeared tightly condensed. The root cause was
twofold:
1. **Integer-only glyph advances.** `advanceX` was stored as a `uint8_t`
of whole pixels, sourced from FreeType's hinted `advance.x` (which
grid-fits to integers). A glyph whose true advance is 15.56px was stored
as 16px -- an error of +0.44px per character that compounds across a
line.
2. **Floor-rounded kerning.** Kern adjustments were converted with
`math.floor()`, which systematically over-tightened negative kerns. A
kern of -0.3px became -1px -- a 0.7px over-correction that visibly
closed gaps.
Combined, these produced the classic symptom: some pairs too wide,
others too tight, with the imbalance varying per word.
#### Solution: fixed-point accumulation with 1/16-pixel resolution, for
sub-pixel precision during text layout
All font metrics now use a "fixed-point 4" format -- 4 fractional bits
giving 1/16-pixel (0.0625px) resolution. This is implemented with plain
integer arithmetic (shifts and adds), requiring no floating-point on the
ESP32.
**How it works:**
A value like 15.56px is stored as the integer `249`:
```
249 = 15 * 16 + 9 (where 9/16 = 0.5625, closest to 0.56)
```
Two storage widths share the same 4 fractional bits:
| Field | Type | Format | Range | Use |
|-------|------|--------|-------|-----|
| `advanceX` | `uint16_t` | 12.4 | 0 -- 4095.9375 px | Glyph advance
width |
| `kernMatrix` | `int8_t` | 4.4 | -8.0 -- +7.9375 px | Kerning
adjustment |
Because both have 4 fractional bits, they add directly into a single
`int32_t` accumulator during layout. The accumulator is only snapped to
the nearest whole pixel at the moment each glyph is rendered:
```cpp
int32_t xFP = fp4::fromPixel(startX); // pixel to 12.4: startX << 4
for each character:
xFP += kernFP; // add 4.4 kern (sign-extends into int32_t)
int xPx = fp4::toPixel(xFP); // snap to nearest pixel: (xFP + 8) >> 4
render glyph at xPx;
xFP += glyph->advanceX; // add 12.4 advance
```
Fractional remainders carry forward indefinitely. Rounding errors stay
below +/- 0.5px and never compound.
#### Concrete example: "drew" in Bookerly
**Before** (integer advances, floor-rounded kerning):
| Char | Advance | Kern | Cursor | Snap | Gap from prev |
|------|---------|------|--------|------|---------------|
| d | 16 px | -- | 33 | 33 | -- |
| r | 12 px | 0 | 49 | 49 | ~2px |
| e | 13 px | -1 | 60 | 60 | ~0px |
| w | 22 px | -1 | 72 | 72 | ~0px |
The d-to-r gap was visibly wider than the tightly packed `rew`.
**After** (12.4 advances, 4.4 kerning, fractional accumulation):
| Char | Advance (FP) | Kern (FP) | Accumulator | Snap | Ink start | Gap
from prev |
|------|-------------|-----------|-------------|------|-----------|---------------|
| d | 249 (15.56px) | -- | 528 | 33 | 34 | -- |
| r | 184 (11.50px) | 0 | 777 | 49 | 49 | 0px |
| e | 208 (13.00px) | -8 (-0.50px) | 953 | 60 | 61 | 1px |
| w | 356 (22.25px) | -4 (-0.25px) | 1157 | 72 | 72 | 0px |
Spacing is now `0, 1, 0` pixels -- nearly uniform. Verified on-device:
all 5 copies of "drew" in the test EPUB produce identical spacing,
confirming zero accumulator drift.
#### Changes
**Font conversion (`fontconvert.py`)**
- Use `linearHoriAdvance` (FreeType 16.16, unhinted) instead of
`advance.x` (26.6, grid-fitted to integers) for glyph advances
- Encode kern values as 4.4 fixed-point with `round()` instead of
`floor()`
- Add `fp4_from_ft16_16()` and `fp4_from_design_units()` helper
functions
- Add module-level documentation of fixed-point conventions
**Font data structures (`EpdFontData.h`)**
- `EpdGlyph::advanceX`: `uint8_t` to `uint16_t` (no memory cost due to
existing struct padding)
- Add `fp4` namespace with `constexpr` helpers: `fromPixel()`,
`toPixel()`, `toFloat()`
- Document fixed-point conventions
**Font API (`EpdFont.h/cpp`, `EpdFontFamily.h/cpp`)**
- `getKerning()` return type: `int8_t` to `int` (to avoid truncation of
the 4.4 value)
**Rendering (`GfxRenderer.cpp`)**
- `drawText()`: replace integer cursor with `int32_t` fixed-point
accumulator
- `drawTextRotated90CW()`: same accumulator treatment for vertical
layout
- `getTextAdvanceX()`, `getSpaceWidth()`, `getSpaceKernAdjust()`,
`getKerning()`: convert from fixed-point to pixel at API boundary
**Regenerated all built-in font headers** with new 12.4 advances and 4.4
kern values.
#### Memory impact
Zero additional RAM. The `advanceX` field grew from `uint8_t` to
`uint16_t`, but the `EpdGlyph` struct already had 1 byte of padding at
that position, so the struct size is unchanged. The fixed-point
accumulator is a single `int32_t` on the stack.
#### Test plan
- [ ] Verify "drew" spacing in Bookerly at small, medium, and large
sizes
- [ ] Verify uppercase kerning pairs: AVERY, WAVE, VALUE
- [ ] Verify ligature words: coffee, waffle, office
- [ ] Verify all built-in fonts render correctly at each size
- [ ] Verify rotated text (progress bar percentage) renders correctly
- [ ] Verify combining marks (accented characters) still position
correctly
- [ ] Spot-check a full-length book for any layout regressions
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**YES, Claude Opus 4.6
helped figure out a non-floating point approach for sub-pixel error
accumulation**_
## Summary
**What is the goal of this PR?**
- Adds `scripts/firmware_size_history.py`, a developer tool that builds
firmware at selected git commits and reports flash usage with deltas
between them.
- Supports two input modes: `--range START END` to walk every commit in
a range, or `--commits REF [REF ...]` to compare specific refs (which
can span branches).
- Defaults to a human-readable aligned table; pass `--csv` for
machine-readable output to stdout or `--csv FILE` to write to a file.
---
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please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**YES, fully written by
AI**_
## Summary
**What is the goal of this PR?**
Rewrite of font routines to use std binary search algorithms instead of
custom repeated implementations: `lookupKernClass`,
`EpdFont::getLigature`, and `EpdFont::getGlyph`.
---
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## Summary
**What is the goal of this PR?**
Small follow up to #909, removing an unused member variable and some
temporary debug logging.
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## Summary
**What is the goal of this PR?**
Added overview and migration guide for ActivityManager changes in #1016.
Thanks for the suggestion, @drbourbon!
---
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Claude 4.6**_
## Summary
**What is the goal of this PR?**
Small tweaks to #1016:
- Only Activity and ActivityManager can access activityResultHandler and
activityResult
- `[[maybe_unused]]` in RenderLock constructor
- Only ActivityManager and RenderLock can access renderingMutex
- Missing renderUpdate after failed wifi selection
- Standardize on activities calling finish instead of
activityManager.popActivity
- Hold RenderLock while mutating state in EpubReaderActivity result
handlers
---
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## Summary
**What is the goal of this PR?**
Correction to #1157, which (embarrassingly) failed to actually include
the updated font header files. (Maybe we should generate these at build
time?)
Add Latin Extended-B glyphs for Croatian, Romanian, Pinyin, and European
diacritical variants. Fixes#921.
---
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please be transparent about their usage as it
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Did you use AI tools to help write this code? _**PARTIALLY, confirmed
codepoint ranges with Claude**_
## Summary
**What is the goal of this PR?**
When update activity finds no update or fails, the "Back" button label
was missing. Fixes#1089.
---
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## Summary
**What is the goal of this PR?**
Probable fix for #1118. `sanitizeFilename` was only passing through
ASCII characters from filenames. It now maintains valid UTF-8
codepoints, including non-ASCII multibyte sequences. Truncation happens
at a maximum number of bytes, rather than characters, to prevent
filenames with many multibyte sequences from unexpectedly exceeding
FAT32 limits.
---
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helps set the right context for reviewers.
Did you use AI tools to help write this code? _**YES, I described #1118
to Claude and it suggested sanitizeFilename as the likely cause**_
## Summary
**What is the goal of this PR?**
Add Latin Extended-B glyphs for Croatian, Romanian, Pinyin, and European
diacritical variants. Fixes#921.
---
### AI Usage
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please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**PARTIALLY, confirmed
codepoint ranges with Claude**_
## Summary
**What is the goal of this PR?**
Following up on #1156: generated language header files should be
ignored.
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## Summary
**What is the goal of this PR?**
I18nKeys.h and I18nStrings.h are generated by gen_i18n.py prior to each
build, so we do not need to maintain a checked-in copy of these files.
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## Summary
**What is the goal of this PR?**
Improved typesetting, including
[kerning](https://en.wikipedia.org/wiki/Kerning) and
[ligatures](https://en.wikipedia.org/wiki/Ligature_(writing)#Latin_alphabet).
**What changes are included?**
- The script to convert built-in fonts now adds kerning and ligature
information to the generated font headers.
- Epub page layout calculates proper kerning spaces and makes ligature
substitutions according to the selected font.
## Additional Context
- I am not a typography expert.
- The implementation has been reworked from the earlier version, so it
is no longer necessary to omit Open Dyslexic, and kerning data now
covers all fonts, styles, and codepoints for which we include bitmap
data.
- Claude Opus 4.6 helped with a lot of this.
- There's an included test epub document with lots of kerning and
ligature examples, shown in the photos.
**_After some time to mature, I think this change is in decent shape to
merge and get people testing._**
After opening this PR I came across #660, which overlaps in adding
ligature support.
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---------
Co-authored-by: Cursor <cursoragent@cursor.com>
## Summary
**What is the goal of this PR?**
Consolidated repeated logic to fall back to REPLACEMENT_GLYPH.
---
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## Summary
**What is the goal of this PR?**
Small cleanup to make getTheme and getMetrics methods on UITheme const.
They return const refs, so updated call sites to use `const auto&`.
Realistically this won't make much performance difference, but it better
conveys the nature of theme metrics being shared const state.
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## Summary
_Revision to @blindbat's #802. Description comes from the original PR._
- Replace `std::list` with `std::vector` for word storage in `TextBlock`
and `ParsedText`
- Use index-based access (`words[i]`) instead of iterator advancement
(`std::advance(it, n)`)
- Remove the separate `continuesVec` copy that was built from
`wordContinues` for O(1) access — now unnecessary since
`std::vector<bool>` already provides O(1) indexing
## Why
`std::list` allocates each node individually on the heap with 16 bytes
of prev/next pointer overhead per node. For text layout with many small
words, this means:
- Scattered heap allocations instead of contiguous memory
- Poor cache locality during iteration (each node can be anywhere in
memory)
- Per-node malloc/free overhead during construction and destruction
`std::vector` stores elements contiguously, giving better cache
performance during the tight rendering and layout loops. The
`extractLine` function also benefits: list splice was O(1) but required
maintaining three parallel iterators, while vector range construction
with move iterators is simpler and still efficient for the small
line-sized chunks involved.
## Files changed
- `lib/Epub/Epub/blocks/TextBlock.h` / `.cpp`
- `lib/Epub/Epub/ParsedText.h` / `.cpp`
## AI Usage
YES
## Test plan
- [ ] Open an EPUB with mixed formatting (bold, italic, underline) —
verify text renders correctly
- [ ] Open a book with justified text — verify word spacing is correct
- [ ] Open a book with hyphenation enabled — verify words break
correctly at hyphens
- [ ] Navigate through pages rapidly — verify no rendering glitches or
crashes
- [ ] Open a book with long paragraphs — verify text layout matches
pre-change behavior
---------
Co-authored-by: Kuanysh Bekkulov <kbekkulov@gmail.com>
## Summary
**What is the goal of this PR?**
`hasPrintableChars` does a pass over text before rendering. It looks up
glyphs in the font and measures dimensions, returning early if the text
results in zero size.
This additional pass doesn't offer any benefit over moving straight to
rendering the text, because the rendering loop already gracefully
handles missing glyphs. This change saves an extra pass over all
rendered text.
Note that both `hasPrintableChars` and `renderChar` replace missing
glyphs with `glyph = getGlyph(REPLACEMENT_GLYPH)`, so there's no
difference for characters which are not present in the font.
---
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## Summary
**What is the goal of this PR?**
This change fixes an issue I noticed while reading where occasionally,
especially in italics, some words would have too much space between
them. The problem was that word width calculations were including any
negative X overhang, and combined with a space before the word, that can
lead to an inconsistently large space.
## Additional Context
Screenshots of some problematic text:
| In CrossPoint 1.0 | With this change |
| -- | -- |
| <img
src="https://github.com/user-attachments/assets/87bf0e4b-341f-4ba9-b3ea-38c13bd26363"
width="400" /> | <img
src="https://github.com/user-attachments/assets/bf11ba20-c297-4ce1-aa07-43477ef86fc2"
width="400" /> |
---
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## Summary
**What is the goal of this PR?**
In some places, button labels are omitted intentionally because the
button has no purpose in the activity. I noticed a few obvious cases,
like Home > File Transfer and Settings > System > Language, where the up
and down button labels were missing. This change fixes those and all
similar instances I could find.
---
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## Summary
**What is the goal of this PR?**
Several methods in GfxRenderer were doing a `count()` followed by `at()`
on the fonts map, effectively doing the same map lookup unnecessarily.
This can be avoided by doing a single `find()` and reusing the iterator.
---
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## Summary
**What is the goal of this PR?**
Skip constructing a `std::string` just to get the underlying `c_str()`
buffer, when a string literal gives the same end result.
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Zach Nelson