* origin:
fix: truncate chapter names that are too long (#422)
feat: dict based Hyphenation (#305)
fix: render U+FFFD replacement character instead of ? (#366)
fix: Invert colors on home screen cover overlay when recent book is selected (#390)
Adds KOReader Sync support (#232)
feat: Change keyboard "caps" to "shift" & Wrap Keyboard (#377)
fix: XTC 1-bit thumb BMP polarity inversion (#373)
## Summary
* Adds (optional) Hyphenation for English, French, German, Russian
languages
## Additional Context
* Included hyphenation dictionaries add approximately 280kb to the flash
usage (German alone takes 200kb)
* Trie encoded dictionaries are adopted from hypher project
(https://github.com/typst/hypher)
* Soft hyphens (and other explicit hyphens) take precedence over
dict-based hyphenation. Overall, the hyphenation rules are quite
aggressive, as I believe it makes more sense on our smaller screen.
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
The current behavior of rendering `?` for an unknown Unicode character
can be hard to distinguish from a typo. Use the standard Unicode
"replacement character" instead, that's what it's designed for:
https://en.wikipedia.org/wiki/Specials_(Unicode_block)
I'm making this PR as a draft because I'm not sure I did everything that
was needed to change the character set covered by the fonts. Running
that script is in its own commit. If this is proper, I'll rebase/squash
into one commit and un-draft.
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
## Summary
- Adds KOReader progress sync integration, allowing CrossPoint to sync
reading positions with other
KOReader-compatible devices
- Stores credentials securely with XOR obfuscation
- Uses KOReader's partial MD5 document hashing for cross-device book
matching
- Syncs position via percentage with estimated XPath for compatibility
# Features
- Settings: KOReader Username, Password, and Authenticate options
- Sync from chapters menu: "Sync Progress" option appears when
credentials are configured
- Bidirectional sync: Can apply remote progress or upload local progress
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* **What is the goal of this PR?** (e.g., Implements the new feature for
file uploading.)
* **What changes are included?**
- Fix inverted colors in Continue Reading cover image for 1-bit XTC
files
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks,
specific areas to focus on).
- Fix `grayValue = pixelBit ? 0 : 255` → `grayValue = pixelBit ? 255 :
0` in `lib/Xtc/Xtc.cpp`
- The thumb BMP generation had inverted polarity compared to cover BMP
generation
- bit=0 should be black, bit=1 should be white (matching the BMP palette
order)
- Update misleading comment about XTC polarity
---
### 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? _**PARTIALLY**_
~~Quick~~ fix for
https://github.com/daveallie/crosspoint-reader/issues/362
(this just applies to the chapter selection menu:)
~~If the orientation is portrait, hints as we know them make sense to
draw. If the orientation is inverted, we'd have to change the order of
the labels (along with everything's position), and if it's one of the
landscape choices, we'd have to render the text and buttons vertically.
All those other cases will be more complicated.~~
~~Punt on this for now by only rendering if portrait.~~
Update: this now draws the hints at the physical button position no
matter what the orientation is, by temporarily changing orientation to
portrait.
---------
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
Let's start small by showing the ALT text of IMG. This is rudimentary,
but avoids those otherwise completely blank chapters.
I feel we will need this even when we can render images if that
rendering takes >1s - I would then prefer rendering optional and showing
the ALT text first.
## Summary
* **What is the goal of this PR?**: Fix the bug I reported in
https://github.com/daveallie/crosspoint-reader/issues/292
* **What changes are included?**: Instead of silently dropping table
content in EPUBs., replace with an italicized '[Table omitted]' message
where tables appear.
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks,
specific areas to focus on).
---
### 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? _**PARTIALLY **_
---------
Co-authored-by: Evan Fenner <evan@evanfenner.com>
Co-authored-by: Warp <agent@warp.dev>
Currently there is no visual indication whatsoever if something is in a
list. An `<li>` is essentially just another paragraph.
As a partial remedy for this, add a bullet character to the beginning of
`<li>` text blocks so that the user can see that they're list items.
This is incomplete in that an `<ol>` should also have a counter so that
its list items can get numbers instead of bullets (right now I don't
think we track if we're in a `<ul>` or an `<ol>` at all), but it's
strictly better than the current situation.
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
Currently, when Extra Paragraph Spacing is off, an em-space is added to
the beginning of each ParsedText even for blocks like headers that are
centered. This whitespace makes the centering slightly off. Change the
calculation here to only add the em-space for left/justified text.
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
## Summary
Skip BOM character (sometimes used in front of em-dashes) - they are not
part of the glyph set and would render `?` otherwise.
---
### AI Usage
Did you use AI tools to help write this code? _**YES**_
## Summary
* **What is the goal of this PR?**
Add support for reading plain text (.txt) files, enabling users to
browse, read, and track progress in TXT documents alongside existing
EPUB and XTC formats.
* **What changes are included?**
- New Txt library for loading and parsing plain text files
- New TxtReaderActivity with streaming page rendering using 8KB chunks
to handle large files without memory issues on ESP32-C3
- Page index caching system (index.bin) for instant re-open after sleep
or app restart
- Progress bar UI during initial file indexing (matching EPUB style)
- Word wrapping with proper UTF-8 support
- Cover image support for TXT files:
- Primary: image with same filename as TXT (e.g., book.jpg for book.txt)
- Fallback: cover.bmp/jpg/jpeg in the same folder
- JPG to BMP conversion using existing converter
- Sleep screen cover mode now works with TXT files
- File browser now shows .txt files
## Additional Context
* Add any other information that might be helpful for the reviewer
* Memory constraints: The streaming approach was necessary because
ESP32-C3 only has 320KB RAM. A 700KB TXT file cannot be loaded entirely
into memory, so we read 8KB chunks and build a page offset index
instead.
* Cache invalidation: The page index cache automatically invalidates
when file size, viewport width, or lines per page changes (e.g., font
size or orientation change).
* Performance: First open requires indexing (with progress bar),
subsequent opens load from cache instantly.
* Cover image format: PNG is detected but not supported for conversion
(no PNG decoder available). Only BMP and JPG/JPEG work.
## Summary
* **What is the goal of this PR?** (e.g., Fixes a bug in the user
authentication module,
Display the book cover image in the **"Continue Reading"** card on the
home screen, with fast navigation using framebuffer caching.
* **What changes are included?**
- Display book cover image in the "Continue Reading" card on home screen
- Load cover from cached BMP (same as sleep screen cover)
- Add framebuffer store/restore functions (`copyStoredBwBuffer`,
`freeStoredBwBuffer`) for fast navigation after initial render
- Fix `drawBitmap` scaling bug: apply scale to offset only, not to base
coordinates
- Add white text boxes behind title/author/continue reading label for
readability on cover
- Support both EPUB and XTC file cover images
- Increase HomeActivity task stack size from 2048 to 4096 for cover
image rendering
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).
- Performance: First render loads cover from SD card (~800ms),
subsequent navigation uses cached framebuffer (~instant)
- Memory: Framebuffer cache uses ~48KB (6 chunks × 8KB) while on home
screen, freed on exit
- Fallback: If cover image is not available, falls back to standard
text-only display
- The `drawBitmap` fix corrects a bug where screenY = (y + offset) scale
was incorrectly scaling the base coordinates. Now correctly uses screenY
= y + (offset scale)
## Summary
- Nav file in EPUB 3 file is a HTML file with relative hrefs
- If this file exists anywhere but in the same location as the
content.opf file, navigating in the book will fail
- Bump the book cache version to rebuild potentially broken books
## Additional Context
- Fixes https://github.com/daveallie/crosspoint-reader/issues/264
---
### 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
- [ ] Partially
- [x] No
1. Refactor Bitmap.cpp/h to expose the options for FloydSteinberg and
brightness/gamma correction at runtime
2. Fine-tune the thresholds for Floyd Steiberg and simple quantization
to better match the display's colors
Turns out that 2 is enough to make the images render properly, so the
brightness boost and gamma adjustment doesn't seem necessary currently
(at least for my test image).
## Summary
* Remove HTML entity parsing
* This has been completely useless since the introduction of expat
* expat tries to parse all entities in the document, but only knows of
HTML ones
* Parsing will never end with HTML entities in the text, so the
additional step to parse them that we had went completely unused
* We should figure out the best way to parse that content in the future,
but for now remove that module as it generates a lot of heap allocations
with its map and strings
## Summary
Adds support for browsing and downloading books from a Calibre-web
server via OPDS.
How it works
1. Configure server URL in Settings → Calibre Web URL (e.g.,
https://myserver.com:port I use Cloudflare tunnel to make my server
accessible anywhere fwiw)
2. "Calibre Library" will now show on the the home screen
3. Browse the catalog - navigate through categories like "By Newest",
"By Author", "By Series", etc.
4. Download books - select a book and press Confirm to download the EPUB
to your device
Navigation
- Up/Down - Move through entries
- Confirm - Open folder or download book
- Back - Go to parent catalog, or exit to home if at root
- Navigation entries show with > prefix, books show title and author
- Button hints update dynamically ("Open" for folders, "Download" for
books)
Technical details
- Fetches OPDS catalog from {server_url}/opds
- Parses both navigation feeds (catalog links) and acquisition feeds
(downloadable books)
- Maintains navigation history stack for back navigation
- Handles absolute paths in OPDS links correctly (e.g.,
/books/opds/navcatalog/...)
- Downloads EPUBs directly to the SD card root
Note
The server URL should be typed to include https:// if the server
requires it - HTTP→HTTPS redirects may cause SSL errors on ESP32.
## Additional Context
* I also changed the home titles to use uppercase for each word and
added a setting to change the size of the side margins
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
Added a setting to select `fit` or `crop` for cover image on sleep
screen.
Might add a `expand` feature in the future that does not crop but rather
fills the blank space with a mirror of the image.
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
This adds the correctly styled button hints to the keyboard screen as
well as the ability to add hints to the side buttons (and up/down hints
to that screen)
## Additional Context
N/A
## Summary
* **What is the goal of this PR?** Add EPUB 3 support by implementing
native navigation document (nav.xhtml) parsing with NCX fallback,
addressing issue Fixes: #143.
* **What changes are included?**
- New `TocNavParser` for parsing EPUB 3 HTML5 navigation documents
(`<nav epub:type="toc">`)
- Detection of nav documents via `properties="nav"` attribute in OPF
manifest
- Fallback logic: try EPUB 3 nav first, fall back to NCX (EPUB 2) if
unavailable
- Graceful degradation: books without any TOC now load with a warning
instead of failing
## Additional Context
* The implementation follows the existing streaming XML parser pattern
using Expat to minimize RAM usage on the ESP32-C3
* EPUB 3 books that include both nav.xhtml and toc.ncx will prefer the
nav document (per EPUB 3 spec recommendation)
* No breaking changes - existing EPUB 2 books continue to work as before
* Tested on examples from
https://idpf.github.io/epub3-samples/30/samples.html
## Summary
* **What is the goal of this PR?**
Add a new user setting for paragraph alignment, instead of hard-coding
full justification.
* **What changes are included?**
One new line in the settings screen, with 4 options
(justify/left/center/right). Default is justified since that's what it
was already. I personally only wanted to disable justification and use
"left", but I included the other options for completeness since they
were already supported.
## Additional Context
Tested on my X4 and looks as expected for each alignment.
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
## Summary
* Update EpdFontFamily::Style to be u8 instead of u32 (saving 3 bytes
per word)
* Update layout width/height to be u16 from int
* Update page element count to be u16 from u32
* Update text block element count to be u16 from u32
* Bumped section bin version to version 8
## Summary
* Swap from Aleo to Bookerly for wider glyph support
* Swap from Space Grotesk to a small Noto Sans
## Additional Context
* 0.11.0 swapped to Aleo which has a few issues (things like Cyrillic
support for eg)
## Summary
* Redesigned home screen with big option to continue reading and
slightly nicer options to navigate to core sections
* Attempt to use the cached EPUB details (title, author) if they exist,
otherwise fall back to file name
* Adjusted button hints on home screen, removed Back option and changed
left/right to up/down
## Additional Context
* Core of this work comes from @ChandhokTannay in
1d36a86ef1
This parses the guide section in the content.opf for text/start
references and jumps to this on first open of the book.
Currently, this behavior will be repeated in case the reader manually
jumps to Chapter 0 and then re-opens the book. IMO, this is an
acceptable edge case (for which I couldn't see a good fix other than to
drag a "first open" boolean around).
---------
Co-authored-by: Sam Davis <sam@sjd.co>
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* Show previous title for unnamed spines
* The spec is a little unclear, but there are plenty of cases where
chapters are split up in parts and should show the previous chapter's
title
* List TOC items instead of spine items in chapter select
* Bump `BOOK_CACHE_VERSION` to `2` to force regeneration of spine item's
TOC indexes
## Summary
* Swap to updated SDCardManager which uses SdFat
* Add exFAT support
* Swap to using FsFile everywhere
* Use newly exposed `SdMan` macro to get to static instance of
SDCardManager
* Move a bunch of FsHelpers up to SDCardManager
## Summary
- **What is the goal of this PR?** Add chapter selection support to the
XTC reader activity, including parsing chapter metadata from XTC files.
- **What changes are included?** Implemented XTC chapter parsing and
exposure in the XTC library, added a chapter selection activity for XTC,
integrated it into XtcReaderActivity, and normalized chapter page
indices by shifting them to 0-based.
## Additional Context
- The reader uses 0-based page indexing (first page = 0), but the XTC
chapter table appears to be 1-based (first page = 1), so chapter
start/end pages are shifted down by 1 during parsing.
## Summary
* Consolidate chapter page data into single file
* Header structure of the file stays the same, following the page count,
we now put a LUT offset
* The page data is all then appended to this file
* Finally the LUT is appended to the end of the file, and the page count
is updated
* This will also significantly improve the duration of cache cleanup
which takes a while to scan the directory and cleanup content
* Remove page file version as it's all tied up into the section file now
* Bumped section file version to 7
* Moved section content into sub directory
* Updated docs
## Additional Context
* Benchmarks:
* Generating 74 pages of content from a chapter in Jade Legacy took:
* master: 6,229ms
* this PR: 1,305ms
* Speedup of 79%
* Generating 207 pages of content from Livesuit book:
* With progress bar UI updates:
* master: 24,250ms
* this PR: 8,063ms
* Speedup of 67%
* Without progress bar UI updates:
* master: 13,055ms
* this PR: 3,600ms
* Speedup of 72%
## Summary
* **What is the goal of this PR?**
Add support for XTC (XTeink X4 native) ebook format, which contains
pre-rendered 480x800 1-bit bitmap pages optimized for e-ink displays.
* **What changes are included?**
- New `lib/Xtc/` library with XtcParser for reading XTC files
- XtcReaderActivity for displaying XTC pages on e-ink display
- XTC file detection in FileSelectionActivity
- Cover BMP generation from first XTC page
- Correct XTG page header structure (22 bytes) and bit polarity handling
## Additional Context
- XTC files contain pre-rendered bitmap pages with embedded status bar
(page numbers, progress %)
- XTG page header: 22 bytes (magic + dimensions + reserved fields +
bitmap size)
- Bit polarity: 0 = black, 1 = white
- No runtime text rendering needed - pages display directly on e-ink
- Faster page display compared to EPUB since no parsing/rendering
required
- Memory efficient: loads one page at a time (48KB per page)
- Tested with XTC files generated from https://x4converter.rho.sh/
- Verified correct page alignment and color rendering
- Please report any issues if you test with XTC files from other
sources.
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* Use font ascender height for baseline offset
* Previously was using font height, but when rendering the font (even
from y = 0), there would be a lot of top margin
* Font would also go below the "bottom of the line" as we were using the
full font height as the baseline
## Additional Context
* This caused some text to move around, I've fixed everything I can
* Notably it moves the first line of font a little closer to the top of
the page
• What is the goal of this PR?
Implement a horizontal EPUB reading mode so books can be read in
landscape orientation (both 90° and 270°), while keeping the rest of the
UI in portrait.
• What changes are included?
◦ Rendering / Display
▪ Added an orientation model to GfxRenderer (Portrait, LandscapeNormal,
LandscapeFlipped) and made:
▪ drawPixel, drawImage, displayWindow map logical coordinates
differently depending on orientation.
▪ getScreenWidth() / getScreenHeight() return orientation‑aware logical
dimensions (480×800 in portrait, 800×480 in landscape).
◦ Settings / Configuration
▪ Extended CrossPointSettings with:
▪ landscapeReading (toggle for portrait vs. landscape EPUB reading).
▪ landscapeFlipped (toggle to flip landscape 180° so both horizontal
holding directions are supported).
▪ Updated settings serialization/deserialization to persist these fields
while remaining backward‑compatible with existing settings files.
▪ Updated SettingsActivity to expose two new toggles:
▪ “Landscape Reading”
▪ “Flip Landscape (swap top/bottom)”
◦ EPUB Reader
▪ In EpubReaderActivity:
▪ On onEnter, set GfxRenderer orientation based on the new settings
(Portrait, LandscapeNormal, or LandscapeFlipped).
▪ On onExit, reset orientation back to Portrait so Home, WiFi, Settings,
etc. continue to render as before.
▪ Adjusted renderStatusBar to position the status bar and battery
indicator relative to GfxRenderer::getScreenHeight() instead of
hard‑coded Y coordinates, so it stays correctly at the bottom in both
portrait and landscape.
◦ EPUB Caching / Layout
▪ Extended Section cache metadata (section.bin) to include the logical
screenWidth and screenHeight used when pages were generated; bumped
SECTION_FILE_VERSION.
▪ Updated loadCacheMetadata to compare:
▪ font/margins/line compression/extraParagraphSpacing and screen
dimensions; mismatches now invalidate and clear the cache.
▪ Updated persistPageDataToSD and all call sites in EpubReaderActivity
to pass the current GfxRenderer::getScreenWidth() / getScreenHeight() so
portrait and landscape caches are kept separate and correctly sized.
Additional Context
• Cache behavior / migration
◦ Existing section.bin files (old SECTION_FILE_VERSION) will be detected
as incompatible and their caches cleared and rebuilt once per chapter
when first opened after this change.
◦ Within a given orientation, caches will be reused as before. Switching
orientation (portrait ↔ landscape) will cause a one‑time re‑index of
each chapter in the new orientation.
• Scope and risks
◦ Orientation changes are scoped to the EPUB reader; the Home screen,
Settings, WiFi selection, sleep screens, and web server UI continue to
assume portrait orientation.
◦ The renderer’s orientation is a static/global setting; if future code
uses GfxRenderer outside the reader while a reader instance is active,
it should be aware that orientation is no longer implicitly fixed.
◦ All drawing primitives now go through orientation‑aware coordinate
transforms; any code that previously relied on edge‑case behavior or
out‑of‑bounds writes might surface as logged “Outside range” warnings
instead.
• Testing suggestions / areas to focus on
◦ Verify in hardware:
▪ Portrait mode still renders correctly (boot, home, settings, WiFi,
reader).
▪ Landscape reading in both directions:
▪ Landscape Reading = ON, Flip Landscape = OFF.
▪ Landscape Reading = ON, Flip Landscape = ON.
▪ Status bar (page X/Y, % progress, battery icon) is fully visible and
aligned at the bottom in all three combinations.
◦ Open the same book:
▪ In portrait first, then switch to landscape and reopen it.
▪ Confirm that:
▪ Old portrait caches are rebuilt once for landscape (you should see the
“Indexing…” page).
▪ Progress save/restore still works (resume opens to the correct page in
the current orientation).
◦ Ensure grayscale rendering (the secondary pass in
EpubReaderActivity::renderContents) still looks correct in both
orientations.
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* **What is the goal of this PR?**
Improve reliability and user experience during chapter indexing by
adding retry logic for SD card operations and a visual progress bar.
* **What changes are included?**
- **Retry logic**: Add 3 retry attempts with 50ms delay for ZIP to SD
card streaming to handle timing issues after display refresh
- **Progress bar**: Display a visual progress bar (0-100%) during
chapter indexing based on file read progress, updating every 10% to
balance responsiveness with e-ink display limitations
## Additional Context
* **Problem observed**: When navigating quickly through books with many
chapters (before chapter titles finish rendering), the "Indexing..."
screen would appear frozen. Checking the serial log revealed the
operation had silently failed, but the UI showed no indication of this.
Users would likely assume the device had crashed. Pressing the next
button again would resume operation, but this behavior was confusing and
unexpected.
* **Solution**:
- Retry logic handles transient SD card timing failures automatically,
so users don't need to manually retry
- Progress bar provides visual feedback so users know indexing is
actively working (not frozen)
* **Why timing issues occur**: After display refresh operations, there
can be timing conflicts when immediately starting SD card write
operations. This is more likely to happen when rapidly navigating
through chapters.
* **Progress bar design**: Updates every 10% to avoid excessive e-ink
refreshes while still providing meaningful feedback during long indexing
operations (especially for large chapters with CJK characters).
* **Performance**: Minimal overhead - progress calculation is simple
byte counting, and display updates use `FAST_REFRESH` mode.
## Summary
* **What is the goal of this PR?**
Replace simple threshold-based grayscale quantization with ordered
dithering using a 4x4 Bayer matrix. This eliminates color banding
artifacts and produces smoother gradients on e-ink display.
* **What changes are included?**
- Add 4x4 Bayer dithering matrix for 16-level threshold patterns
- Modify `grayscaleTo2Bit()` function to accept pixel coordinates and
apply position-based dithering
- Replace simple `grayscale >> 6` threshold with ordered dithering
algorithm that produces smoother gradients
## Additional Context
* Bayer matrix approach: The 4x4 Bayer matrix creates a repeating
pattern that distributes quantization error spatially, effectively
simulating 16 levels of gray using only 4 actual color levels (black,
dark gray, light gray, white).
* Cache invalidation: Existing cached `cover.bmp` files will need to be
deleted to see the improved rendering, as the converter only runs when
the cache is missing.
## Summary
* **What is the goal of this PR?** Fixes a bug where text disappears
after approximately 25 pages in long chapters during EPUB indexing.
* **What changes are included?**
- Removed the `MAX_LINES = 1000` hard limit in
`ParsedText::computeLineBreaks()`
- Added safer infinite loop prevention by checking if `nextBreakIndex <=
currentWordIndex` and forcing advancement by one word when stuck
## Additional Context
* **Root cause:** The `MAX_LINES = 1000` limit was introduced to prevent
infinite loops, but it truncates content in long chapters. For example,
a 93KB chapter that generates ~242 pages (~9,680 lines) gets cut off at
~1000 lines, causing blank pages after page 25-27.
* **Solution approach:** Instead of a hard line limit, I now detect when
the line break algorithm gets stuck (when `nextBreakIndex` doesn't
advance) and force progress by moving one word at a time. This preserves
the infinite loop protection while allowing all content to be rendered.
* **Testing:** Verified with a Korean EPUB containing a 93KB chapter -
all 242 pages now render correctly without text disappearing.
## Summary
This creates a `renderer.drawButtonHints` to make all of the "hints"
over buttons to match the home screen.
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
Replace linear O(n) search with binary search O(log n) for unicode
interval lookup. Korean fonts have many intervals (~30,000+ glyphs), so
this improves text rendering performance during page navigation.
## Summary
* **What is the goal of this PR?** (e.g., Fixes a bug in the user
authentication module, Implements the new feature for
file uploading.)
Replace linear `O(n)` glyph lookup with binary search `O(log n)` to
improve text rendering performance during page navigation.
* **What changes are included?**
- Modified `EpdFont::getGlyph()` to use binary search instead of linear
search for unicode interval lookup
- Added early return for empty interval count
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).
- Performance implications: Fonts with many unicode intervals benefit
the most. Korean fonts have ~30,000+ glyphs across multiple intervals,
but any font with significant glyph coverage (CJK, extended Latin,
emoji, etc.) will see improvement.
- Complexity: from `O(n)` to `O(log n)` where n = number of unicode
intervals. For fonts with 10+ intervals, this reduces lookup iterations
significantly.
- Risk: Low - the binary search logic is straightforward and the
intervals are already sorted by unicode codepoint (required for the
original early-exit optimization).
