Ctrl+Grid

Repository: https://github.com/DocAtPrompt/ctrlgrid

Generate dimensionally accurate PDF templates from a small definition file: grid paper, ruled paper, dot grids, staff paper, mazes, polar targets, tilings, fillable forms, perspective grids and mandalas — plus a linked, write-on calendar and a notebook that binds any of them into one document — for paper formats and for e-ink tablets.

Status: 0.11.0 — everything the specification describes is built, audited against a first-time user, and every generator's geometry read back out of a finished PDF. The eleven generators of the table below work, and so do the two document generators (calendar, notebook); the dimensional test described below measures lines out of a finished PDF on every commit, and net puts the same promise in your hands — print a box net, cut it, fold it. The handle around them is finished — multi-page output, headers and footers, name lists, snapping, remainder handling, double-sided margins, border, background, hole marks, stamp, an edge ruler, the calibration cover sheet, embedded font files, dashed and dotted styles, free page sizes, logos in bands, and relative measures (%w/%h/%s) so one definition fills paper and a 3:4 e-ink slate alike.

Nothing in the specification is left unbuilt, so nothing refuses with "a later milestone" any more. What is left is not code: a device to verify two profile figures on, and a pair of scissors for the box nets.

Working today:

ctrlgrid millimeter-a4 --pages 30 -o grid.pdf
ctrlgrid calendar-a4 -o 2026.pdf            # a whole linked year planner
ctrlgrid millimeter-a4 --names class3b.txt      # a sheet per name
ctrlgrid -d my-def.yaml --stamp DRAFT
ctrlgrid millimeter-a4 --cover              # + a calibration first sheet
ctrlgrid check my-def.yaml
ctrlgrid dots-5mm --device remarkable-paper-pro   # an e-ink profile
ctrlgrid millimeter-a4 --format a6 --pages 4 --nup 2x2   # four-up on A4
ctrlgrid presets | show <name> | devices

Flags: --pages, --names, --format, --device, --orientation, --stamp, --cover, --embed-def, --seed, --strict, --skip-unsupported, --nup, --nup-sheet, --crop-marks, -o, --force, --quiet.

Not on PyPI yet — install straight from this repository (see below).

Examples

A gallery of A4 examples — one per generator, plus a multi-page maze booklet and a whole linked calendar — is in examples/, each an ordinary definition file you can copy and bend.

The one promise

What says 5 mm measures 5 mm on the printout. No scaling, no "fit to page", no stretching a grid so it comes out even. If a grid does not fit the page, you are told — it is never quietly adjusted.

That promise is enforced by a test that generates a PDF, reads it back and measures it, on every commit.

Why another one

Of roughly 60 comparable tools surveyed (docs/research.md), three can emit more than one page and none can drive page content from a list. Ctrl+Grid is built around exactly that: one command, one finished multi-page PDF.

# 30 sheets of millimetre paper
ctrlgrid millimeter-a4 --pages 30 -o grid.pdf

# one sheet per name, each with the name in the header
ctrlgrid millimeter-a4 --names class3b.txt

# a different maze on every page, reproducibly
ctrlgrid maze-medium --pages 20 --seed 4711

# your own definition, on Letter, with a calibration cover sheet
ctrlgrid -d my-def.yaml --format letter --pages 5 --cover

# no arguments: browse the presets interactively
ctrlgrid

Installation

Not on PyPI yet, so install straight from this repository. With uv:

# run it once, without installing anything
uvx --from git+https://github.com/DocAtPrompt/ctrlgrid.git ctrlgrid --help

# or install it as a tool on your PATH
uv tool install git+https://github.com/DocAtPrompt/ctrlgrid.git
ctrlgrid --help

Or with pip, into an environment of your choosing:

pip install git+https://github.com/DocAtPrompt/ctrlgrid.git

To work on it, clone and let uv build the environment:

git clone https://github.com/DocAtPrompt/ctrlgrid.git
cd ctrlgrid
uv sync --extra dev
uv run ctrlgrid --help

Python 3.11 or newer. There are no double-clickable installers, and none are planned.

What it generates

Generator	Produces
lines	squared, ruled, isometric, calligraphy (slanted families), Cornell, log/semi-log
dots	dot grids with emphasised rows and columns
staves	music staves and guitar tab, with treble/bass/alto/tenor clefs
grid	labelled cell blocks — battleship, score sheets
maze	rectangular mazes, optionally with solutions
polar	targets, score discs, polar paper
tiling	hexagons, triangles, rhombi — including colouring patterns
form	fillable forms: phone logs, checklists, handover sheets
perspective	one-, two- and three-point vanishing-point grids
mandala	rotationally symmetric templates: rings, rosettes, star polygons
net	box nets: a tray or a tuck-top carton from its inner dimensions

Each of those fills one page, as many times as you ask for — net fills it with one figure you cut out and fold, and refuses rather than scale it. Two document generators are the exception, producing whole linked documents instead: calendar, which has its own section below, and notebook — sections of pages, each filled by one of the ten above, with a contents page that links to them:

generator: notebook
sections:
  - { label: "Bullet journal", pages: 40, divider: true, generator: dots,
      grid: { x: { base_spacing: 5mm }, y: { base_spacing: 5mm } } }
  - { label: "Music", pages: 10, generator: staves, count: 10,
      stave_space: 1.8mm, clef: treble }

One PDF on an e-ink device instead of twelve — ctrlgrid notebook-a4 -o notebook.pdf, or see examples/15-notebook.yaml.

The interesting part is the cycle model: spacing, stroke weight, size, dash pattern and colour each follow their own repeating list, and the lists may have different lengths. "Every fifth line heavier and blue, every third dashed" is one definition, not a special case.

A linked, write-on calendar

ctrlgrid calendar-a4 -o 2026.pdf

calendar is the one generator that is not a sheet: it owns a whole document — a cover, a contents page, the year on one sheet as twelve mini-months, two half-year tables, twelve months, one page per day, opt-in week pages and as many note pads as you like. Every date is an internal PDF link, so on a pen tablet you tap a date and land on that day, tap a note number and land on that note. About 400 pages from one definition, in a second, and the same definition always gives the same PDF.

generator: calendar
year: 2026
week_start: monday
months: [Januar, Februar, …]        # your language; English if omitted
holidays: [{ date: 2026-12-25, label: Weihnachten }]
holidays_file: feiertage.ics        # or a YAML list — merged with the above
day:
  blocks:                           # an ordered list: reorder, resize, repeat
    - { type: schedule, from: 8, to: 20, height: 55%, half_hours: true }
    - { type: todo,     rows: 6,         height: 20% }
    - { type: notes,    height: rest,    surface: grid }
notes:
  - { count: 20, surface: lines, label: "Journal" }
  - { count: 10, surface: dots,  label: "Sketches" }

Marked days carry their own colour — a birthday is not a public holiday — and a legend on the contents page says what each colour means, because the calendar knows the colours and never their meanings. Names come from your definition, so the calendar adds no language of its own. It is PDF only: links and text cannot live in a PNG, and the run is refused rather than quietly stripped of its links.

The whole example is examples/12-calendar-year.yaml; the preset is ctrlgrid show calendar-a4, and HANDBOOK.md documents every option.

Definition files

A definition is YAML with a version line. Start from a preset and change it:

ctrlgrid presets              # list them
ctrlgrid show millimeter-a4   # print one, ready to copy
ctrlgrid check my-def.yaml    # validate without generating

A header or footer field holds free text or a picture — left: { image: "logo.png", height: 8mm }, PNG, with the path relative to the definition file. Only the height is given; the width follows from the file, so a logo is never squeezed, and never cropped: it fits or you are told.

Paper size is either a name from the built-in table or two measures of your own, width first — format: 210x99mm, format: 8.5x11in. A free size is used exactly as written; orientation: landscape swaps the two.

The presets are the documentation. They are ordinary definition files, not a separate mechanism, so anything a preset does you can do too — and there is no second syntax reference here to drift out of date.

E-ink devices

ctrlgrid devices                              # list known profiles
ctrlgrid dots-5mm --device remarkable-paper-pro

Device profiles carry pixels and physical size, so millimetres stay millimetres, and a profile makes the PDF page match the screen exactly — which is what makes the usual "fit page" view show it at true size. On a device you can also write lengths in px, and snap: pixel rounds every step to whole device pixels so the grid looks even (§ 8.3.1) — it reports the size it settled on, e.g. 5mm → 4.991mm (45px at 229dpi), because a silent change of size is the one thing this tool will not do.

As soon as the medium is fixed the tool checks the definition against it and warns about what will not work there — a line too thin to render, a spacing that merges, two colours that become the same grey (§ 12.1). --strict turns those warnings into errors, which is what a CI run needs to guard a preset set.

Output a PNG by giving -o name.png: it rasters at the medium's exact resolution — the Paper Pro's 1620 × 2160 px — one file per page, which is what a real pad template needs. The PNG writer cannot draw text (the standard fonts have metrics but no file), so a definition with a header, footer or labels on PNG is refused up front, naming the way out: a font file, or PDF.

Adding a profile for your device is the easiest useful contribution — see CONTRIBUTING.md.

Known limitations

Please read these. Each one is a real constraint, and each looks like a bug if you meet it without warning.

1. Print at 100 %, not "fit to page". Most PDF viewers default to fitting the page and silently scale to about 96 %. Choose "Actual size" / "100 %". Run with --cover to get a first sheet with a 50 mm calibration square and a 100 mm rule: measure them with a ruler and you will know immediately whether your printer scaled. For the check on every sheet rather than the first one, add a ruler: — a printed scale along the edges of the page, zeroed on the pattern area, so a real ruler laid against it settles the question at a glance (examples/13-ruler-edge.yaml). That sheet also records the settings that produced the document — format, margins, base values, cycles, effective period, tool version and a checksum of the definition — so a print that came out right stays reproducible. It is not counted in the page numbering, and it is never scaled to fit: on a format too narrow for the 100 mm rule the run is refused rather than shrunk.

For the fullest record, add --embed-def: the PDF then carries its own source as a file attachment — the exact definition it was built from — so the document can be regenerated years later without hunting for the file. PDF only; on PNG output the run is refused with the reason rather than dropping the attachment.

2. Character coverage is Latin-1 by default. Without a font file of your own, ä ö ü ß é à ñ ç work but ł ğ ő do not — you will hit this on the first Polish or Turkish name in a list. The fix is to point at a font file — a path, never a font name, because name lookup finds different fonts on different machines:

header:
  height: 12mm
  left: "{name}"
  font: { file: "~/Library/Fonts/EBGaramond-Regular.ttf", size: 11pt }

The font is embedded and subset, so the PDF is the same everywhere. Its embedding licence is checked, not assumed: a font whose fsType forbids embedding aborts the run and is named — never quietly swapped for another one, which would change every measurement on the sheet. A character the file itself lacks is still an error, now naming the file.

3. Margins below about 5 mm get clipped by most printers. The default comes from the paper format and reflects the typical non-printable border; e-ink profiles use 0.

4. N-up does not scale. --nup 2x2 places pages at 100 % and fails with the arithmetic if they do not fit, unlike pdfjam and pdfcpu. The intended use is the reverse of the usual one: define a small format, impose it onto a large sheet, cut it up — --format a6 --nup 2x2 puts four A6 pages on A4. --crop-marks adds cut guides in the margin; --nup-sheet picks the sheet. Imposition drops PDF bookmarks, and the calibration cover sheet is left out of it.

5. {date} makes output date-dependent. Two runs on different days produce different files. If you want a reproducible sheet, write the date as text.

6. Solutions printed on the back need long-edge duplex. solution: back_mirrored prints the maze solution mirrored on the reverse so it lines up when held to the light. Short-edge flipping puts it upside down, and whether it shows through at all depends on your paper.

7. There is no GUI, and none is planned. ctrlgrid with no arguments opens an interactive preset browser — pick a preset, a page count and an output path (§ 11.2) — and that is as far as it goes. Piped or in CI, where there is no one to answer, it prints its help instead.

Documentation

• HANDBOOK.md — the user handbook: install, the page model, every generator and option, with worked examples. Start here.
• docs/pflichtenheft-vorlagengenerator.md — the full specification, in German. Records not just what the tool does but why.
• docs/implementation-decisions.md — the points where the specification was silent, and what was decided instead.
• docs/research.md — survey of comparable tools, July 2026.
• CONTRIBUTING.md — how to add device profiles, presets and code.

Licence

MIT — see LICENSE.

The bundled clef font in ctrlgrid/data/fonts/ is derived from Bravura © Steinberg Media Technologies GmbH, under the SIL Open Font License 1.1 — subset to the four clef glyphs, converted to TrueType, and renamed as the OFL requires for a modified version.