82 lines
2.4 KiB
TypeScript
82 lines
2.4 KiB
TypeScript
import { byte } from '../types';
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/**
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* Printer UI. The "paper" is bound to the element selected by the input.
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*
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* Every line that is output to the printer is added as a <div> to the paper.
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* The high bit of all characters is stripped and only visible characters are
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* added to the output. The following characters receive special treatment:
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*
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* * `EOT` (ASCII 4): deletes last character
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* * `HT` (ASCII 9): replaced with 8 spaces
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* * `LF` (ASCII 10): silently removed
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* * `CR` (ASCII 13): a newline and carriage return
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*/
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export default class Printer {
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private paper: HTMLElement;
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private _lineBuffer = '';
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private _line: HTMLElement;
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private _rawLen = 0;
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private _raw = new Uint8Array(1024);
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/**
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* Creates a new printer bound to the given element.
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* @param {string} el The selector of the element on which to bind the "paper".
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*/
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constructor(el: string) {
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this.paper = document.querySelector(el)!;
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this.newLine();
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}
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private newLine() {
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this._line = document.createElement('div');
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this._line.classList.add('line');
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this._line.innerText = this._lineBuffer;
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this.paper.append(this._line);
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this._lineBuffer = '';
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}
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putChar(val: byte) {
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const ascii = val & 0x7f;
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const visible = val >= 0x20;
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const c = String.fromCharCode(ascii);
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if (c === '\r') {
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this.newLine();
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} else if (c === '\n') {
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// eat for now
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} else if (c === '\t') {
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// possibly not right due to tab stops
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this._lineBuffer += ' ';
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} else if (ascii === 0x04) {
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this._lineBuffer = this._lineBuffer.slice(0, -1);
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} else if (visible) {
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this._lineBuffer += c;
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}
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this._line.innerText = this._lineBuffer;
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this._raw[this._rawLen] = val;
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this._rawLen++;
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if (this._rawLen > this._raw.length) {
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const newRaw = new Uint8Array(this._raw.length * 2);
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newRaw.set(this._raw);
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this._raw = newRaw;
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}
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}
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clear() {
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this._lineBuffer = '';
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this.paper.innerHTML = '';
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this.newLine();
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this._raw = new Uint8Array(1024);
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this._rawLen = 0;
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}
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hasPrintout() {
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return this.paper.innerText.length > 0;
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}
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getRawOutput() {
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return this._raw.slice(0, this._rawLen);
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}
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}
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