escpos/document

A high-level API for building ESC/POS printer documents.

Documents are built by composing commands and modifiers, then compiled into a binary command buffer that can be sent to a printer.

Example

import escpos/document.{bold, cut, justify, line, styled, text, Center}

document.render([
  styled([justify(Center), bold()], [
    line([text("Receipt")]),
  ]),
  line([text("Item 1 ... $5.00")]),
  cut(),
])

Types

Command

opaque </>

A command representing a print operation or content.

pub opaque type Command

Font

</>

Printer font. Re-exported from escpos/protocol.

pub type Font =
  protocol.Font

Justify

</>

Text justification. Re-exported from escpos/protocol.

pub type Justify =
  protocol.Justify

Modifier

opaque </>

A style modifier that affects how text is rendered.

pub opaque type Modifier

Values

bold

</>

pub fn bold() -> Modifier

Bold text modifier.

cut

</>

pub fn cut() -> Command

Performs a full paper cut.

double_strike

</>

pub fn double_strike() -> Modifier

Double-strike (heavier print) modifier.

flip

</>

pub fn flip() -> Modifier

Flips text 180 degrees.

font

</>

pub fn font(f: protocol.Font) -> Modifier

Sets the font.

image

</>

pub fn image(image: image.PrintableImage) -> Command

Prints an image.

Example

let assert Ok(pgm) = simplifile.read_bits(from: "./lucy.pgm")
let assert Ok(img) = image.from_pgm(raw_pgm)
let img = image.dither_bayer4x4(img, 0)

document.render([
  image(img),
  cut(),
])

justify

</>

pub fn justify(j: protocol.Justify) -> Modifier

Sets text justification.

line

</>

pub fn line(commands: List(Command)) -> Command

Groups commands into a single line, with a newline at the end. Useful for combining styled and unstyled text on one line.

Example

line([
  styled([bold()], [text("Total:")]),
  text(" $12.99"),
])

line_feed

</>

pub fn line_feed(lines: Int) -> Command

Advances the paper by the specified number of lines.

new_line

</>

pub fn new_line() -> Command

Advances the paper by one line.

partial_cut

</>

pub fn partial_cut() -> Command

Performs a partial paper cut, leaving a small portion connected.

raw

</>

pub fn raw(bytes: BitArray) -> Command

Sends raw ESC/POS bytes to the printer.

render

</>

pub fn render(document: List(Command)) -> @internal CommandBuffer

Compiles a list of commands into a binary command buffer ready for printing.

reverse

</>

pub fn reverse() -> Modifier

Reverse (white on black) text modifier.

styled

</>

pub fn styled(
  modifiers: List(Modifier),
  commands: List(Command),
) -> Command

Applies style modifiers to a group of commands. Styles are automatically reverted after the nested commands.

text

</>

pub fn text(t: String) -> Command

Prints text without a trailing newline.

text_height

</>

pub fn text_height(size: Int) -> Modifier

Sets text height scaling (0-7).

text_size

</>

pub fn text_size(size: Int) -> Modifier

Sets both text width and height scaling (0-7).

text_width

</>

pub fn text_width(size: Int) -> Modifier

Sets text width scaling (0-7).

underline

</>

pub fn underline() -> Modifier

Underlined text modifier.

upside_down

</>

pub fn upside_down() -> Modifier

Prints text upside down (requires newline before and after).