Commands

ESC/POS command builders for the GoojPrt PT-210.

Every function in this module is pure: it has no side effects, performs no I/O, and merely returns the byte sequence that the caller sends over the chosen transport (BLE or SPP).

Two levels of helpers are provided:

• Low-level builders (init(), align(), bold(), feed(), cut(), …) emit a single ESC/POS escape sequence.

• Composite builders (build_text_block(), build_qr_block()) concatenate several low-level commands into a ready-to-send block. These are shared by the BLE and SPP print APIs of GoojPrtPT210 to avoid duplicating byte construction logic.

Reference: ESC/POS Command Reference by Epson. Only the subset implemented by the PT-210 firmware is exposed here.

goojprt.commands.align(a: Align) → bytes

ESC a n — set horizontal alignment (LEFT / CENTER / RIGHT).

goojprt.commands.barcode_qr(data: str, size: int = 6, error_correction: int = 1) → bytes

GS ( k — build the four-command sequence that prints a QR code.

The sequence configures the model/error-correction level, stores the payload into the printer’s symbol buffer, and then triggers printing.

Parameters:

• data – Payload to encode (encoded as UTF-8 on the wire).

• size – Module size, 1–16 (default 6).

• error_correction – Correction level — 0=L, 1=M, 2=Q, 3=H (default 1).

Returns:

Bytes containing the complete QR command sequence.

goojprt.commands.bold(enabled: bool) → bytes

ESC E n — toggle emphasised (bold) printing.

goojprt.commands.build_qr_block(data: str, size: int = 6, align_val: Align = Align.CENTER, error_correction: int = 1) → bytes

Build a QR block: alignment + QR command sequence + trailing newline.

Shared by both the BLE and SPP QR APIs.

goojprt.commands.build_text_block(text: str, align_val: Align = Align.LEFT, bold_on: bool = False, underline_on: bool = False, size_val: TextSize = TextSize.NORMAL, newline: bool = True, encoding: str = 'gb2312') → bytes

Build the full ESC/POS block that prints a single text line.

The resulting byte stream contains, in order: alignment, bold toggle, underline toggle, text-size setting, the encoded text, and (optionally) a trailing line feed. This function is shared by BLE and SPP print APIs to keep the wire format identical.

goojprt.commands.charset(cp: CodePage) → bytes

ESC t n — select code page for native ESC/POS text output.

goojprt.commands.cut() → bytes

GS V A — paper cut (no-op on PT-210, which lacks a cutter).

goojprt.commands.energy(dots: int = 7, heating: int = 120, interval: int = 2) → bytes

ESC 7 n1 n2 n3 — configure thermal head heating parameters.

Parameters:

• dots – Maximum number of simultaneously heated dots, 0–7. Higher values print faster but draw more current.

• heating – Heating time, 0–255. Higher values produce darker output (the factory default is ≈ 80).

• interval – Heating interval, 0–255. Lower values print faster (the factory default is ≈ 2).

goojprt.commands.feed(lines: int = 1) → bytes

ESC d n — feed paper by lines rows (clamped to 0–255).

goojprt.commands.font(font_b: bool = False) → bytes

ESC M n — select font. False = Font A (12×24), True = Font B (9×17).

goojprt.commands.init() → bytes

ESC @ — initialise the printer (reset it to its default state).

goojprt.commands.line_spacing(dots: int = 30) → bytes

ESC 3 n — set line spacing, measured in motion units (0–255).

goojprt.commands.text_size(s: TextSize) → bytes

GS ! n — set character size (NORMAL / DOUBLE_HEIGHT / …).

goojprt.commands.underline(enabled: bool) → bytes

ESC - n — toggle underline printing.