Receipt Renderer in Rust (ESC/POS)

Thermal is a printer emulator, it converts the esc/pos commands that thermal printers use into images or html.

If you are looking for a receipt renderer language, see my other project instead: Rip: Receipt Image Platform.

Supports:

Rendering to HTML and Images
Human-readable format for commands (see docs)
Page Mode
Barcodes
Qr Codes
Some codepages (see docs)
International

Plans

Crate (We currently don't have a crate published but will publish soon when we feel that the library has sufficient

tests.)

WASM Library
Playground
CLI

Read the docs

TOC:

Image Rendering Example
Html Rendering Example
Thermal File Format
Sample Renders

Image Rendering

// Read string from thermal file
let text = readtostring("hello_world.thermal");
//Parse into esc/pos commands let bytes = parse_str( & text);
//Render to image let renders = ImageRenderer::render(bytes, None);
// renders.output may contain multiple renders // For this example we grab the first. // // Write the image to a file. // Error handling is left out for brevity if let Some(render) = renders.output.first() { saveimage( & render.bytes, render.width, render.height, "helloworld.png"); }
// Error handling is left out for brevity // png crate required for this example fn saveimage(bytes: &Vec<u8>, width: u32, height: u32, outpath: String) {     let path = Path::new(&out_path);     let file = File::create(path).unwrap();     let ref mut writer = BufWriter::new(file);     let mut encoder = png::Encoder::new(writer, width, height);
encoder.set_color(png::ColorType::Rgb);     encoder.set_depth(BitDepth::Eight);
let mut writer = encoder.write_header().unwrap();     writer.writeimagedata(bytes).unwrap(); }

Html Rendering

// Read string from thermal file
let text = readtostring("hello_world.thermal");
//Parse into esc/pos commands let bytes = parse_str( & text);
//Render to html let renders = HtmlRenderer::render(bytes, None);
// renders.output may contain multiple renders // For this example we grab the first. // // Write the html to a file. // Error handling is left out for brevity if let Some(render) = renders.output.first() { let mut file = File::create("hello_world.html").unwrap(); file.writeall(render.content.asbytes()); }

Thermal File Format:

This library supports raw binary, but also has support for a human readable format based on the programming examples from the Epson website. We have created a VsCode sytax highlighting plugin for this format, see the thermal_vscode directory for installation instructions.

Example:

'// Initialize printer ESC "@" '// Justify Center ESC "a" 1 '// Set font size to double GS "!" 0x11 '// Print text "Hello World" '// Select bit-image mode: 8-dot single-density, 48 byte column data ESC "*" 0 48 0 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x07 0x07 0x09 0x09 0x7D 0x7C 0x10 0x10 0x16 0x16 0x10 0x70 0xF8 0xFC 0x7E 0x3E 0x3E 0x7E 0xFE 0xFC 0x70 0x10 0x16 0x16 0x10 0x10 0x7C 0x7D 0x09 0x09 0x07 0x07 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 '// --- Print barcode --->>> '// Print and feed paper: Paper feeding amount = 4.94 mm (35/180 inches) ESC "J" 35 '// Set barcode height: in case TM-T20, 6.25 mm (50/203 inches) GS "h" 50 '// Select print position of HRI characters: Print position, below the barcode GS "H" 2 '// Select font for HRI characters: Font B GS "f" 1 '// Print barcode: (A) format, barcode system = CODE39 GS "k" 4 "00014" 0

'// Select cut mode and cut paper GS "V" 66 30

Samples

See the sample_files directory for more.

Typography:

Typography

Page Mode:

Page Mode

Barcodes and QR:

Barcodes

Fonts

Font included in this repo do not fall under this repos licence.

See thermal_render/resources/fonts/OFL.txt for the license. Fonts were obtained from JetBrains Mono repository on Github: https://github.com/JetBrains/JetBrainsMono

Inspiration/References:

https://github.com/receipt-print-hq/escpos-tools
https://github.com/local-group/rust-escposify
https://github.com/buntine/barcoders
https://reference.epson-biz.com/modules/refescpos/index.php?contentid=72

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