apple2js/js/components/Printer.tsx

import { h, Fragment } from 'preact';
import { useCallback, useEffect, useMemo, useRef, useState } from 'preact/hooks';
import Apple2IO, { slot } from 'js/apple2io';
import Parallel, { ParallelOptions } from 'js/cards/parallel';
import { Modal, ModalContent, ModalFooter } from './Modal';

import styles from './css/Printer.module.scss';
import { ControlButton } from './ControlButton';
import { byte } from 'js/types';

export interface PrinterProps {
    io: Apple2IO | undefined;
    slot: slot;
}

export const Printer = ({ io, slot }: PrinterProps) => {
    const [isOpen, setIsOpen] = useState(false);
    const [content, setContent] = useState('');
    const raw = useRef(new Uint8Array(1024));
    const rawLength = useRef(0);
    const [href, setHref] = useState('');

    const cbs = useMemo<ParallelOptions>(() => ({
        putChar: (val: byte) => {
            const ascii = val & 0x7f;
            const visible = val >= 0x20;
            const char = String.fromCharCode(ascii);

            if (char === '\r') {
                // Skip for once
            } else if (char === '\t') {
                // possibly not right due to tab stops
                setContent((content) => content += '        ');
            } else if (ascii === 0x04) {
                setContent((content) => content = content.slice(0, -1));
                return;
            } else if (visible) {
                setContent((content) => content += char);
            }

            raw.current[rawLength.current++] = val;
            if (rawLength.current > raw.current.length) {
                const newRaw = new Uint8Array(raw.current.length * 2);
                newRaw.set(raw.current);
                raw.current = newRaw;
            }
        }
    }), [rawLength]);

    useEffect(() => {
        if (io) {
            const parallel = new Parallel(cbs);
            io.setSlot(slot, parallel);
        }
    }, [cbs, io, slot]);

    useEffect(() => {
        if (isOpen) {
            const blob = new Blob(
                [raw.current.slice(0, rawLength.current)],
                { type: 'application/octet-stream' }
            );
            const href = window.URL.createObjectURL(blob);
            setHref(href);
        }
    }, [isOpen]);

    const onClear = useCallback(() => {
        setContent('');
        rawLength.current = 0;
    }, []);
    const onClose = useCallback(() => {
        setIsOpen(false);
    }, []);
    const onOpen = useCallback(() => {
        setIsOpen(true);
    }, []);

    return (
        <>
            <Modal isOpen={isOpen} onClose={onClose} title="Printer">
                <ModalContent>
                    <pre className={styles.printer} tabIndex={-1} >
                        {content}
                    </pre>
                </ModalContent>
                <ModalFooter>
                    <a
                        download="raw_printer_output.bin"
                        href={href}
                        role="button"
                    >
                        Download Raw
                    </a>
                    <button onClick={onClear}>Clear</button>
                    <button onClick={onClose}>OK</button>
                </ModalFooter>
            </Modal>
            <ControlButton
                icon="print"
                title="Printer"
                onClick={onOpen}
                active={content.length > 0}
            />
        </>
    );
};