PDF Occlusion turns any PDF into an image-occlusion deck — masks grouped into cards, reviewed as proper cloze flashcards on the PDF so you always have context. Draw, group, and edit masks in a built-in editor with zoom, drag-to-move, and deck selection per PDF. Ideal for textbook chapters, lecture slides, and anatomy/histology atlases.

New Features

27-07-26

• Filename repair: long PDF names are now shortened at import, and a new one-time migration normalises existing filenames — fixing pages broken by Anki's "Check Media" rename (scroll view / page navigation not loading)
• ⇧ + draw: hold Shift while drawing to add the rectangle to the same group as the previous one
• Portrait page fixes: single-page view scrolls inside its own viewport (no more cut-off top/bottom), cursor-anchored zoom works at every zoom level
• Smarter focus: new questions and the ⌂ button centre on the active card's masks instead of the page middle
• Peek stability: individually revealed masks stay open while zooming

21-07-26

• Single image occlusion: import one image as a standalone occlusion note — via Tools → PDF Occlusion → Import image… or by right-clicking any image in the Add window and choosing Occlude image (respects the Add window's deck selection). Same editor, no page navigation, not part of the PDF library
• Text annotations zoom-proof: annotation text now scales in lockstep with the page at every zoom level and is rendered identically on front and back — exactly the proportions set in the editor
• Scroll view improvements: each new question re-centres on its card page and caps the zoom at page width, so you never land somewhere else in the PDF; page-scroll no longer leaks into other cards or decks
• Per-mask peek polish: revealing a single mask on the question side now hides its hint label too
• Import dialog fixes: correct size, no clipped text, and the currently selected deck is pre-selected

08-07-26

• Continuous scroll view (Beta): browse the whole PDF top-to-bottom during review like a real PDF reader — toggle via Scroll button or S, ⌘/Ctrl + wheel zooms the PDF only (cursor-anchored, 0.2×–6×), notes shown in a floating side panel
• Text annotations: place free text on any page (mode 5/T) with size slider, colour, bold and italic — rendered identically on the cards
• Per-mask labels: hints are set per rectangle instead of per group, so masks within one group can carry different labels
• Exports fixed: page images are now officially referenced from the note, so .apkg deck exports include them
• Transparent page fix: imports are flattened onto a white background; one-click repair with progress bar for existing images via Tools → PDF Occlusion → Fix transparent page borders
• Manage PDFs upgraded: first-page thumbnails and a Due column
• Editor improvements: segmented icon tool buttons (✋ ▭ ✥ ⌫ T) with Draw as default, "Show note in browser" button, line breaks preserved in Notes, floating text-format panel
• Review UI polish: "Soft Pill" navigation bar, Hide all toggle covers other masks in neutral grey, ✎ button opens the editor for the current page

19-05-26

• Folders in Manage PDFs dialog: group PDFs into folders, subfolders via Parent::Child scheme
• Protected against "Check Media → Delete Unused": PDF page images are no longer incorrectly flagged as unused. One-time migration runs automatically on first start
• Editor improvements: Notes field editable inline, DPI choice at import (Standard / High Resolution), shortcuts R and E for Rectangle and Edit mode
• Reliability: robust note lookup for PDF names with special characters, left-side page preview now works consistently, editor opens without forcing a profile reload

26-04-25

• Hide other Occlusions in Study mode
• Bug fixes

25-04-25

• Set labels for occlusions
• Stabilisation of cards order inside a note after deleting a card
• Use ⌥ + </> to navigate

Usage

Import a PDF

Tools → PDF Occlusion → Import PDF… Pick a PDF and a target deck. The editor opens automatically.

Draw masks

• Mode 2 (Draw): drag to add a mask — each mask starts its own group.
• Mode 3 (Edit): click/shift-click to select, drag to move, G to group selected, U to ungroup, Delete to remove.
• Ctrl+S or "Save page": writes the masks and regenerates cards.

Each mask (or group) becomes one flashcard. The tooltip after saving shows N mask(s) → M group(s) → K active card(s).

Review

Cards show the page with the current group's masks opaque and the other masks transparent — you see the full context. Above the page there's a ◀ Page 5 / 30 ▶ navigation bar, plus small peek strips of the adjacent pages on either side. Click the arrows, the page strip or just the peek strips to jump pages. Home button (⌂) returns to the question page.

Manage PDFs

Tools → PDF Occlusion → Manage PDFs… Lists all imported PDFs with page/card counts. Per PDF:

• Open the editor
• Rename
• Move all cards to a different deck
• Delete (removes notes + media files)

Other commands

• Open PDF viewer… — pick from dropdown and edit
• Open context viewer for current card (Ctrl+Shift+P) — during review, open a floating side-panel synced to the current card
• Repair note metadata — run the idempotent in-place migration. Use in case of a broken navigation bar
• Migrate legacy notes… — one-time upgrade from the pre-0.2 type

How it's stored

A cloze note type called PDF Occlusion is created with these fields:

• PDF Name — logical name (used to group pages)
• Page Number — 1-based
• Page Image — bare filename of the PNG
• Occlusions — JSON: [{x,y,w,h,group}, ...] (normalised to 0–1)
• Groups — cloze deletions, e.g. {{c1::g1::g1}}{{c2::g2::g2}}
• Notes — free-form text shown on the back
• PDF Prefix — filename prefix for adjacent-page navigation
• Total Pages — total page count of the PDF

Card template shows each group as one cloze deletion; the JS layer renders masks from the JSON positioned as percentage overlays.

© C. Ritter