# 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_FINE, PEN_MEDIUM, ERASER, SELECT, BOX),
  zoom/pan state, pen width constants (4.49pt, 5.91pt)
- [x] 3.6: EditorViewModel — loads strokes from Room, saves on completion
- [x] 3.7: EditorScreen + Toolbar — Compose wrapper with AndroidView,
  FilterChip toolbar for pen size and eraser selection
- [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–4×)
- [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 (×0.24), 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 removing backing bitmap entirely and drawing paths directly.
  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.

Known issues still to address:
- CopyStrokesAction uses `takeLast(n)` to find new stroke IDs — fragile
- No mutex guarding concurrent page navigation + paste operations
- Grid redrawn every frame (could be cached)

## 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. Remaining work:
- Test on Supernote Manta
- Verify line snap behavior on device
- Performance profiling with heavily annotated pages
- Implement notebook backup/restore

## 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).