A ticket designer for Boca Systems printers, in Rust on GPUI.
One window. The ticket on the left, everything that changes it on the right. Drag things around, set a quantity, hit print. What leaves the app is plain FGL — Boca's "Friendly Ghost Language" — so the source panel shows byte for byte what the printer receives.
Ticketsmith.dmg — the latest release for macOS 12 or later, Apple silicon and Intel in one app, signed and notarized. Older versions are on the releases page.
The app keeps itself current: the status bar shows the version, and when a newer release is out, a link beside it downloads the update and restarts into it.
cargo run # launch
cargo test # 98 tests
scripts/bundle.sh # build target/Ticketsmith.app
The first build takes a few minutes because it compiles GPUI. After that it is
seconds. Releases are cut with scripts/release.sh; see
RELEASING.md.
Stock. Defaults to the standard 2" x 5.5" ticket at 200 dpi. Both dimensions are free, and the head density can be 200, 300 or 600 dpi. The status bar shows the resulting dot grid, because FGL positions everything in dots.
Layout. Add text, barcodes, the printer's own ticket counter, rules and boxes. Drag them on the preview, or nudge with the arrow keys — shift for a coarser step, escape to deselect, cmd-backspace to delete. Everything is measured the way the printer measures it: text is laid out one font box-advance per character, so what you see is where the dots land.
The preview draws the ticket in FGL's own orientation, the 5.5" feed axis running
left to right. That is both how a Boca ticket is held and how <RC row,column>
numbers read, so the preview and the inspector never disagree.
Barcodes. Code 128, Code 39, Interleaved 2 of 5, Codabar, UPC-A, EAN-13 and QR, with orientation, bar height, narrow-bar width, the 3:1 ratio where the symbology allows it, and the human-readable interpretation. Data is validated per symbology as you type, and UPC/EAN check digits are worked out for you.
Printing. Set the quantity and the job goes out as one stream with an <RE>
repeat, which is how the printer runs at full speed. Turn on numbering and the
run comes out sequentially numbered from the printer's own counter.
Four routes, covering both connections these printers ship with:
| Target | What it is |
|---|---|
| Ethernet | Raw TCP to port 9100. Every Boca ethernet and WiFi interface listens there. |
| USB device | A device node. This is USB when the printer's port is in serial mode (<usbs>): /dev/cu.usbmodem* on macOS, /dev/ttyACM0 or /dev/usb/lp0 on Linux. |
| Print queue | lp -d QUEUE -o raw. This is USB when the printer is left in its default printer mode (<usbp>) and installed as a CUPS queue. macOS and Linux. |
| Save .fgl | Write the job to disk. Test the whole pipeline without burning stock. |
Sending runs on the background executor, so a printer that is switched off waits out its connect timeout without freezing the window.
The core is plain Rust with no UI dependency and carries most of the tests.
| File | |
|---|---|
src/fgl.rs |
FGL command emission: the resident fonts and their dot metrics, rotation, text, rules, boxes, the ticket counter, print and repeat commands. |
src/barcode.rs |
Symbology validation, FGL emission, GTIN check digits, and bar/space modules for the preview. |
src/ticket.rs |
The document: stock size, elements, element geometry, hit testing, and the whole-job emitter. |
src/transport.rs |
The four ways out. |
src/update.rs |
Checking GitHub for a newer release, and verifying and installing it. |
src/preview.rs |
Projection from printer dots to window pixels, and all the painting. |
src/app.rs |
The GPUI window: toolbar, preview interaction, inspector, print panel. |
gpui-kit is one dependency that pulls in GPUI (published as gpui-pre) plus
gpui-component, a component library
built on top of it. GPUI itself has no text input, dropdown or checkbox — Zed
builds its own — and this app is mostly a form, so the component library is doing
real work here.
Rotated glyphs. GPUI's paint API can rotate SVG paths but not quads or shaped text. A rotated text element is drawn with upright glyphs stepped along the true rotated advance: the footprint is exact and the characters stay legible, but they are not turned the way the printer turns them. A small tick marks the direction so the difference is visible.
Two symbologies' bar patterns. Bars are the real encoding for Code 39, Interleaved 2 of 5, UPC-A and EAN-13. For Code 128 and Codabar the preview draws the exact footprint with representative bars, and the inspector says so. QR shows the exact symbol size with finder patterns.
That second one is less a shortcut than a description of where the work happens: the printer encodes every symbol in firmware, including Code 128 code-set switching and check digits. The app sends a payload and delimiters. Sizing and placement are what a print preview is for, and those are exact.
Boca Systems FGL46/FGL26 Programming Guide, revision 16.1, 20 June 2024. Command syntax, font metrics and the barcode supplements all come from there.
MIT.