eng-pad/PROGRESS.md

# PROGRESS.md — eng-pad Implementation Progress

This file tracks completed work and decisions. Updated after every step.
See PROJECT_PLAN.md for the full step list.

## Completed

### Phase 0: Project Documents (2026-03-24)

- [x] 0.1: Created DESIGN.md — full technical design covering architecture,
  data model, coordinate system, rendering, input handling, and source tree.
- [x] 0.2: Created PROJECT_PLAN.md — discrete steps grouped by phase with
  checkboxes and file references.
- [x] 0.3: Created PROGRESS.md — this file.
- [x] 0.4: Updated CLAUDE.md — build commands, source tree, project doc
  pointers.

### Phase 1: Project Skeleton + Data Layer (2026-03-24)

- [x] 1.1: Generated Android project — Gradle 8.14.2, AGP 8.10.1, Kotlin 2.1.20
- [x] 1.2: Version catalog with Compose BOM 2026.03.00, Room 2.8.4,
  Navigation 2.9.7, Lifecycle 2.10.0
- [x] 1.3: Lint configured — warningsAsErrors, AGP version check suppressed
  (AGP 9.x needs Gradle 9.x)
- [x] 1.4: Room entities: Notebook, Page, Stroke, PageSize enum
- [x] 1.5: Converters: FloatArray <-> ByteArray (packed little-endian)
- [x] 1.6: DAOs: NotebookDao, PageDao, StrokeDao
- [x] 1.7: EngPadDatabase (Room, version 1)
- [x] 1.8: NotebookRepository, PageRepository
- [x] 1.9: Unit tests: StrokeBlobTest (6 tests), PageSizeTest (4 tests) — all pass
- Foojay resolver added for automatic JDK toolchain download
- compileSdk/targetSdk bumped to 36 (required by latest androidx dependencies)

### Phase 2: Notebook List Screen (2026-03-24)

- [x] 2.1: MainActivity with Compose NavHost (three routes: notebooks, pages, editor)
- [x] 2.2: NotebookListViewModel with StateFlow, create/delete operations
- [x] 2.3: NotebookListScreen — lazy list, create dialog (title + page size radio),
  long-press delete with confirmation, empty state
- [x] 2.4: Auto-create page 1 in NotebookRepository.create()
- [x] 2.5: Navigation wired — tap notebook -> pages stub, editor stub
- EngPadTheme: high-contrast light color scheme (black on white for e-ink)

### Phase 3: Canvas — Basic Drawing (2026-03-24)

- [x] 3.1-3.4: PadCanvasView — stylus input with historical points, Path/Paint
  stroke rendering, direct path drawing (no backing bitmap), 60pt grid
  drawn in screen space with pixel-snapped positions, Matrix coordinate
  transform (canonical <-> screen)
- [x] 3.5: CanvasState — tool enum (PEN, LINE, BOX, ERASER, SELECT, MOVE),
  zoom/pan state, PenSize enum with 4 sizes
- [x] 3.6: EditorViewModel — loads strokes from Room, saves on completion
- [x] 3.7: EditorScreen + Toolbar — Compose wrapper with AndroidView,
  icon-button toolbar with long-press menus for pen size and line style
- [x] 3.8: NavGraph updated — pages route auto-navigates to first page's editor,
  page size passed through route params
- Used KTX Canvas extensions (withMatrix, withScale, createBitmap) per lint
- ClickableViewAccessibility suppressed on PadCanvasView (drawing view)

### Phase 4: Zoom and Pan (2026-03-24)

- [x] 4.1: ScaleGestureDetector with focal-point zoom (dynamic min-4x)
- [x] 4.2: Finger drag for pan with multi-pointer tracking, pan clamped
  so page always fills viewport
- [x] 4.3: Input routing by tool type already in place from Phase 3
- Zoom/pan state managed locally in PadCanvasView for responsiveness,
  synced to ViewModel on gesture end
- Minimum zoom computed dynamically from page/view dimensions

### Phase 5: Eraser (2026-03-24)

- [x] 5.1-5.3: Stroke-level eraser with bounding box hit test (42pt radius),
  processes historical touch points for thorough erasing, deletes from
  view + Room DB

### Phase 6: Undo/Redo (2026-03-24)

- [x] 6.1: UndoableAction interface, AddStrokeAction, DeleteStrokeAction
- [x] 6.2: UndoManager with undo/redo stacks (depth 50), StateFlow for canUndo/canRedo
- [x] 6.3: EditorViewModel rewired — stroke add/delete go through UndoManager,
  visual callbacks sync canvas view without full reload
- [x] 6.4: 9 unit tests for UndoManager (perform, undo, redo, depth limit, clear, no-ops)
- Toolbar now has undo/redo buttons with enabled state

### Phase 7: Selection — Move, Copy, Delete (2026-03-24)

- [x] 7.1-7.2: Rectangle selection with dashed rect and blue highlight
- [x] 7.3: Delete, drag-to-move, copy operations with toolbar buttons
- [x] 7.4: Full undo integration — DeleteMultipleStrokesAction, MoveStrokesAction,
  CopyStrokesAction
- Drag existing selection to move, tap outside to deselect

### Phase 8: Multi-Page Navigation (2026-03-24)

- [x] 8.1: PageListScreen — adaptive grid of page cards with correct aspect ratio
- [x] 8.2: Add new page via FAB
- [x] 8.3: NavGraph refactored — pages route loads notebook metadata then shows
  PageListScreen, tap page navigates to editor with page size

### Phase 9: PDF Export (2026-03-24)

- [x] 9.1: PdfExporter — creates PdfDocument, scales canonical 300 DPI coords
  to 72 DPI PDF points (x0.24), renders strokes without grid
- [x] 9.2: Share via Intent.ACTION_SEND + FileProvider (configured in Phase 1)
- [x] 9.3: PDF button in editor toolbar, exports current page

### Phase 10: Polish (2026-03-24)

- [x] 10.1: High-contrast e-ink theme — expanded color scheme with proper
  container, variant, and outline colors for readability
- [x] 10.2: Auto-save already in place since Phase 3 (strokes save on completion)
- [x] 10.3: Empty states and delete confirmations already in place from Phase 2
- [ ] 10.4: Performance profiling — requires on-device testing

### On-Device Testing — Daylight DC-1 (2026-03-24)

Tested on DC-1, identified and fixed rendering issues:

- **Grid**: original grid drawn in canonical space had uneven spacing due to
  sub-pixel positioning when scaled. Fixed by drawing grid in screen space
  with pixel-snapped line positions. Now uniform squares.
- **Stroke quality**: original backing bitmap at 1/4 resolution caused blurry
  strokes. Fixed by switching to a screen-resolution backing bitmap with
  incremental stroke addition. Anti-aliasing disabled on all paint for
  crisp e-ink lines.
- **Viewport**: dark gray background was visible around page edges. Fixed by
  clamping pan to page edges, computing dynamic min zoom, and white background.
- **Box tool**: works correctly on device.
- **PDF export**: correctly elides grid — confirmed on device.
- **Line snap**: increased threshold to 60pt (~5mm) and switched to max-distance
  tracking to handle EMR stylus hand tremor.

### Code Audit & Bug Fixes (2026-03-24)

Critical/high-priority fixes applied:
- **MoveStrokesAction.undo()**: was offsetting by (0,0) instead of restoring
  original positions. Fixed to write back the pre-move point data.
- **Stroke commit flicker**: backing bitmap was fully redrawn on each new
  stroke. Fixed with incremental rendering — new strokes draw directly
  onto the existing bitmap without clearing.
- **Selection state leak**: view-side selection wasn't cleared on page
  navigation. Added `onPageNavigated` callback.
- **Initial page fallback**: if `initialPageId` isn't found in DB,
  fall back to first page instead of showing blank canvas.
- **Arrow head Paint allocation**: preallocated reusable Paint object
  instead of allocating per drawArrowHeads() call.
- **CopyStrokesAction**: fixed `takeLast(n)` fragile ID lookup — now
  tracks copied stroke IDs directly.
- **Grid caching**: grid bitmap is now cached and only redrawn on
  zoom/pan/resize changes.

### Post-Phase 10: Feature Polish (2026-03-24)

Extensive feature work after the initial 10-phase plan:

- **Toolbar redesign**: replaced FilterChip toolbar with icon-button toolbar.
  Custom Canvas-drawn icons for each tool (pen dot, line, box outline,
  eraser, dashed-rect select, four-way-arrow move, curved undo/redo arrows).
- **Pen size consolidation**: expanded from 2 sizes to 4 sizes (0.38mm,
  0.5mm, 0.6mm, 0.7mm). Single PEN tool with long-press for size selection
  dropdown; remembers last size.
- **Line tool**: dedicated LINE tool (separate from PEN) with style variants
  via long-press menu: plain, arrow, double-arrow, dashed. Line style stored
  in stroke `style` column in DB.
- **Box tool**: draws rectangles corner-to-corner. Uses current pen size
  and style.
- **Move tool**: dedicated MOVE tool for tap-and-drag stroke relocation
  (separate from select-then-drag).
- **Edge swipe navigation**: finger swipe from left/right screen edge
  navigates to previous/next page. Auto-creates new page on forward swipe
  past last page (if current page has strokes). Edge zone = 8% of screen
  width, minimum 100px horizontal distance.
- **Page list drag-to-reorder**: long-press drag in PageListScreen to
  reorder pages. Uses `longPressDraggableHandle` with reorderable lazy
  column. Page numbers renumbered sequentially on drop.
- **Notebook rename**: long-press notebook in library list to rename.
  Rename dialog with text field.
- **Library filter/sort**: search field to filter notebooks by title,
  sort by last-edited or title (ascending/descending).
- **JPG export**: single-page JPEG export at 300 DPI via Export dropdown
  menu. Uses `Bitmap.compress(JPEG, 95)`, shared via FileProvider + intents.
- **Clipboard operations**: cut, copy, paste toolbar buttons appear when
  strokes are selected or clipboard is non-empty. Cut = copy + delete.
- **Startup state restoration**: SharedPreferences in EngPadApp store last
  opened notebook ID and view-all-pages flag. On launch, auto-navigates to
  last notebook (or page list if that was the last screen).
- **Page navigation from editor**: binder button in toolbar shows
  "p1/5"-style page indicator with dropdown for "View all pages" and
  "Go to page..." dialog.
- **Last page tracking**: Notebook entity has `lastPageId` column; editor
  resumes at last-visited page when reopening a notebook.
- **Page delete**: delete pages from PageListScreen with sequential
  renumbering of remaining pages.
- **Database migrations**: schema at version 3 (added `style` column to
  strokes, `last_page_id` to notebooks).

## Backup Design (Not Yet Implemented)

Notebook backup as a zip file:
- Export: `notebook_title.engpad.zip` containing:
  - `notebook.json` — notebook metadata (title, page_size, page count)
  - `pages/` directory with one JSON per page:
    - `pages/001.json` — page metadata + strokes array
    - Each stroke: `{penSize, color, style, points: [x0,y0,x1,y1,...]}`
  - Points stored as JSON float arrays (portable, human-readable)
- Import: parse zip, create notebook + pages + strokes in DB
- Could be shared via Android share intents like PDF/JPG export
- Consider: export all notebooks as a single zip for full backup,
  or individual notebook export for sharing

Alternative: SQLite `VACUUM INTO` for raw DB backup (simpler but not
portable or human-readable).

## Status

All implementation phases complete. Post-phase polish significantly extended
the feature set beyond the original plan. Remaining work:
- Test on Supernote Manta
- Performance profiling with heavily annotated pages
- Implement notebook backup/restore (zip format)
- Server sync integration (eng-pad-server, gRPC, manual sync)

## Decisions & Deviations

- **Language**: Kotlin (chosen over Java for better Compose/coroutine support).
- **Storage**: Room/SQLite with packed float BLOBs for stroke points.
- **Palm rejection**: Hardware only (EMR digitizer handles it).
- **Pressure sensitivity**: None — four pen sizes (0.38, 0.5, 0.6, 0.7mm).
- **Coordinate system**: 300 DPI canonical points (scaled to 72 DPI for PDF export).
- **UI framework**: Compose for chrome, custom View for canvas (Compose
  Canvas lacks MotionEvent access needed for stylus input).
- **Toolbar**: Icon buttons with Canvas-drawn icons (no drawable resources needed
  for tool icons). Long-press for sub-menus (pen size, line style).
- **Rendering**: Screen-resolution backing bitmap with incremental stroke
  addition + cached grid bitmap. Both invalidated on zoom/pan/resize.
- **Line styles**: Stored as string in stroke `style` DB column (plain, dashed,
  arrow, double_arrow) rather than a separate table.
- **State restoration**: SharedPreferences for last notebook/page rather than
  Compose SavedStateHandle (survives process death).