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import type { OcrWord } from './Ocr';
export { copyPng, copyText, downloadBlob, printPage } from '@platform';
export function hostOf(url: string) {
try {
return new URL(url).hostname.replace(/^www\./, '');
} catch {
return '';
}
}
export function formatBytes(bytes: number) {
if (bytes < 1024) return `${bytes} B`;
if (bytes < 1024 ** 2) return `${(bytes / 1024).toFixed(0)} KB`;
if (bytes < 1024 ** 3) return `${(bytes / 1024 ** 2).toFixed(1)} MB`;
return `${(bytes / 1024 ** 3).toFixed(2)} GB`;
}
export function fileName(shot: Pick<Shot, 'url' | 'createdAt'>, ext: string) {
const d = new Date(shot.createdAt);
const p = (n: number) => String(n).padStart(2, '0');
const host = hostOf(shot.url);
return `Daguerre ${host ? `${host} ` : ''}${d.getFullYear()}-${p(d.getMonth() + 1)}-${p(d.getDate())} at ${p(d.getHours())}.${p(d.getMinutes())}.${p(d.getSeconds())}.${ext}`;
}
export function canvasToBlob(
canvas: HTMLCanvasElement,
type = 'image/png',
quality?: number,
) {
return new Promise<Blob>((resolve, reject) =>
canvas.toBlob(
(b) =>
b ? resolve(b) : reject(new Error('The image is too large to encode.')),
type,
quality,
),
);
}
export interface PdfImage {
jpeg: Uint8Array<ArrayBuffer>;
width: number;
height: number;
/** OCR words in this image's pixels, written as an invisible, selectable text layer. */
words?: OcrWord[];
}
// Standard-font text must be WinAnsi; map the common non-Latin-1 punctuation, '?' for the rest.
const WIN_ANSI: Record<string, number> = {
'€': 0x80,
'‚': 0x82,
'„': 0x84,
'…': 0x85,
'‘': 0x91,
'’': 0x92,
'“': 0x93,
'”': 0x94,
'•': 0x95,
'–': 0x96,
'—': 0x97,
'™': 0x99,
};
const winAnsi = (s: string) =>
Uint8Array.from(s, (c) =>
c.charCodeAt(0) < 256 ? c.charCodeAt(0) : (WIN_ANSI[c] ?? 63),
);
/**
* Minimal PDF: one JPEG per page, scaled to page width and pinned to the top.
* `measure` returns a string's width at font size 1 in Helvetica.
*/
export function buildPdf(
images: PdfImage[],
pageW: number,
pageH: number,
measure: (text: string) => number = (t) => t.length * 0.5,
) {
const enc = new TextEncoder();
const parts: Uint8Array[] = [];
const offsets: number[] = [];
let length = 0;
const push = (p: string | Uint8Array) => {
const bytes = typeof p === 'string' ? enc.encode(p) : p;
parts.push(bytes);
length += bytes.length;
};
const obj = (n: number, dict: string, stream?: Uint8Array) => {
offsets[n] = length;
push(`${n} 0 obj\n${dict}\n`);
if (stream) {
push('stream\n');
push(stream);
push('\nendstream\n');
}
push('endobj\n');
};
const num = (v: number) => String(+v.toFixed(2));
push('%PDF-1.4\n%\u00e2\u00e3\u00cf\u00d3\n');
obj(1, '<< /Type /Catalog /Pages 2 0 R >>');
obj(
2,
`<< /Type /Pages /Kids [${images.map((_, i) => `${4 + i * 3} 0 R`).join(' ')}] /Count ${images.length} >>`,
);
obj(
3,
'<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>',
);
images.forEach((img, i) => {
const page = 4 + i * 3;
const s = pageW / img.width;
const drawH = img.height * s;
// Render mode 3 = invisible: selectable and searchable, but the image stays what you see.
const words = (img.words ?? []).flatMap((w) => {
const text = w.text.replace(/[\r\n]/g, ' ');
const size = (w.y1 - w.y0) * s;
const natural = measure(text) * size;
if (size <= 0 || natural <= 0) return [];
const tz = (100 * (w.x1 - w.x0) * s) / natural;
return `${num(size)} 0 0 ${num(size)} ${num(w.x0 * s)} ${num(pageH - w.y1 * s)} Tm ${num(tz)} Tz (${text.replace(/[\\()]/g, '\\$&')}) Tj`;
});
const content = winAnsi(
`q ${num(pageW)} 0 0 ${num(drawH)} 0 ${num(pageH - drawH)} cm /Im0 Do Q` +
(words.length ? `\nBT 3 Tr /F1 1 Tf\n${words.join('\n')}\nET` : ''),
);
obj(
page,
`<< /Type /Page /Parent 2 0 R /MediaBox [0 0 ${num(pageW)} ${num(pageH)}] /Resources << /XObject << /Im0 ${page + 2} 0 R >> /Font << /F1 3 0 R >> >> /Contents ${page + 1} 0 R >>`,
);
obj(page + 1, `<< /Length ${content.length} >>`, content);
obj(
page + 2,
`<< /Type /XObject /Subtype /Image /Width ${img.width} /Height ${img.height} /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /DCTDecode /Length ${img.jpeg.length} >>`,
img.jpeg,
);
});
const xref = length;
const size = 4 + images.length * 3;
push(
`xref\n0 ${size}\n0000000000 65535 f \n${offsets
.slice(1)
.map((o) => `${String(o).padStart(10, '0')} 00000 n \n`)
.join('')}`,
);
push(`trailer\n<< /Size ${size} /Root 1 0 R >>\nstartxref\n${xref}\n%%EOF\n`);
const out = new Uint8Array(length);
let at = 0;
for (const p of parts) {
out.set(p, at);
at += p.length;
}
return out;
}
/** Splits the image across A4 pages (landscape for wide images); `words` adds a searchable text layer. */
export async function canvasToPdf(
canvas: HTMLCanvasElement,
words?: OcrWord[],
) {
const [pageW, pageH] =
canvas.width > canvas.height ? [841.89, 595.28] : [595.28, 841.89];
const sliceH = Math.floor((canvas.width * pageH) / pageW);
const slice = document.createElement('canvas');
slice.width = canvas.width;
const images: PdfImage[] = [];
for (let y = 0; y < canvas.height; y += sliceH) {
slice.height = Math.min(sliceH, canvas.height - y);
const ctx = slice.getContext('2d')!;
ctx.fillStyle = '#fff';
ctx.fillRect(0, 0, slice.width, slice.height);
ctx.drawImage(
canvas,
0,
y,
slice.width,
slice.height,
0,
0,
slice.width,
slice.height,
);
const jpeg = new Uint8Array(
await (await canvasToBlob(slice, 'image/jpeg', 0.92)).arrayBuffer(),
);
const pageWords = words
?.filter(
(w) => (w.y0 + w.y1) / 2 >= y && (w.y0 + w.y1) / 2 < y + slice.height,
)
.map((w) => ({ ...w, y0: w.y0 - y, y1: w.y1 - y }));
images.push({
jpeg,
width: slice.width,
height: slice.height,
words: pageWords,
});
}
const ctx = slice.getContext('2d')!;
ctx.font = '100px Helvetica, Arial, sans-serif';
return new Blob(
[buildPdf(images, pageW, pageH, (t) => ctx.measureText(t).width / 100)],
{ type: 'application/pdf' },
);
}
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