Files

mod: Phase 1 - bring forward mod-exclusive files with ActivityManager migration

Brings ~55 mod-exclusive files to the upstream-based mod/master-resync branch:

Activities (migrated to new ActivityManager pattern):
- Clock/Time: SetTimeActivity, SetTimezoneOffsetActivity, NtpSyncActivity
- Dictionary: DictionaryDefinitionActivity, DictionarySuggestionsActivity,
  DictionaryWordSelectActivity, LookedUpWordsActivity
- Bookmark: EpubReaderBookmarkSelectionActivity
- Book management: BookManageMenuActivity, EndOfBookMenuActivity
- OPDS: OpdsServerListActivity, OpdsSettingsActivity
- Utility: DirectoryPickerActivity, NumericStepperActivity

Utilities (unchanged):
- BookManager, BookSettings, BookmarkStore, BootNtpSync
- Dictionary, LookupHistory, TimeSync, OpdsServerStore

Libraries: PlaceholderCover, TableData, ChapterXPathIndexer
Scripts: inject_mod_version, generate_book_icon, preview_placeholder_cover
Docs: KOReader sync XPath mapping

Migration changes:
- ActivityWithSubactivity -> Activity base class
- Callback constructors -> finish()/setResult() pattern
- enterNewActivity() -> startActivityForResult()
- Activity::RenderLock&& -> RenderLock&&

These files won't compile yet - they reference mod settings and I18n
strings that will be added in subsequent phases.

Made-with: Cursor

2026-03-07 15:10:00 -05:00

2.9 KiB

Raw Blame History

Letterbox Fill: Replace Dithering with Edge Replication ("Extend Edges")

Date: 2026-02-13

Task Description

After implementing Bayer ordered dithering for the "Blended" letterbox fill mode (replacing earlier noise dithering), the user reported that the problematic cover (The World in a Grain by Vince Beiser) looked even worse. Investigation revealed that any dithering technique is fundamentally incompatible with the e-ink multi-pass rendering pipeline for large uniform fill areas:

The BW HALF_REFRESH pass creates a visible dark/white pattern in the letterbox
The subsequent greyscale correction can't cleanly handle mixed-level patterns in large uniform areas
This causes crosstalk artifacts that can affect adjacent cover rendering
Uniform fills (all same level, like Solid mode) work fine because all pixels go through identical correction

The user's key insight: the display already renders the cover's grayscale correctly (including Atkinson-dithered mixed levels). Instead of re-dithering an averaged color, replicate the cover's actual boundary pixels into the letterbox -- letting the display render them the same way it renders the cover itself.

Changes Made

`src/CrossPointSettings.h`

Renamed LETTERBOX_BLENDED (value 2) → LETTERBOX_EXTENDED
Updated comment to reflect "None / Solid / Extend Edges"

`src/SettingsList.h`

Changed UI label from "Blended" → "Extend Edges"

`src/activities/boot_sleep/SleepActivity.cpp`

Removed: BAYER_4X4 matrix, quantizeBayerDither() function (all Bayer dithering code)
Added: getPackedPixel(), setPackedPixel() helpers for packed 2-bit array access
Rewrote LetterboxFillData struct:
- Added edgeA/edgeB (dynamically allocated packed 2-bit arrays) for per-pixel edge data
- Added edgePixelCount, scale for coordinate mapping
- Added freeEdgeData() cleanup method
Renamed computeEdgeAverages() → computeEdgeData():
- New captureEdgePixels parameter controls whether to allocate and fill edge arrays
- For horizontal letterboxing: captures first/last visible BMP rows
- For vertical letterboxing: captures leftmost/rightmost pixel per visible row
- Still computes averages for SOLID mode in the same pass
Rewrote drawLetterboxFill():
- SOLID mode: unchanged (uniform fill with snapped level)
- EXTENDED mode: maps screen coordinates → BMP coordinates via scale factor, looks up stored 2-bit pixel values from the cover's boundary row/column
Updated renderBitmapSleepScreen(): new log messages, freeEdgeData() call at end

Backward Compatibility

Enum value 2 is unchanged (was LETTERBOX_BLENDED, now LETTERBOX_EXTENDED)
Serialized settings files continue to work without migration

Follow-up Items

Test "Extend Edges" mode with both covers (Power Broker and World in a Grain)
Test vertical letterboxing (left/right) if applicable covers are available
Verify SOLID mode still works as expected

2.9 KiB Raw Blame History