valknar
1037b84eaa
scripts/cover.js computes the exact cover canvas dimensions from the page count in book-meta.json (written by build.js), using the KDP Premium Color spine formula (0.002347 in/page), and renders a Nunjucks template to a single PDF containing back cover, spine, and front cover with bleed (0.125 in) and safe-zone overlay guides. - `pnpm cover` — generate output/cover.pdf - `pnpm all` — build interior + both PDFs in one command - Cover artwork slots: images/cover/front.png, images/cover/back.png Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
100 lines
3.6 KiB
JavaScript
100 lines
3.6 KiB
JavaScript
import puppeteer from 'puppeteer';
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import { readFile, writeFile, access } from 'fs/promises';
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import { resolve, dirname } from 'path';
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import { fileURLToPath } from 'url';
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import nunjucks from 'nunjucks';
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const __dir = dirname(fileURLToPath(import.meta.url));
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const root = resolve(__dir, '..');
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// KDP constants — Premium Color paper, 8.5×8.5 in trim
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const BLEED_IN = 0.125;
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const TRIM_W_IN = 8.5;
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const TRIM_H_IN = 8.5;
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const SPINE_PER_PAGE = 0.002347; // inches per page, Premium Color
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const SAFE_IN = 0.125; // safe zone inset from trim edge (front/back)
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const SPINE_SAFE_IN = 0.0625; // safe zone inset from spine fold (each side)
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const MIN_SPINE_TEXT = 79; // KDP minimum pages for spine text
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async function fileExists(p) {
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try { await access(p); return true; } catch { return false; }
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}
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async function generate() {
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// Read page count produced by build.js
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const metaPath = resolve(root, 'output', 'book-meta.json');
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let pageCount = 100;
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if (await fileExists(metaPath)) {
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const meta = JSON.parse(await readFile(metaPath, 'utf-8'));
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pageCount = meta.pageCount;
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console.log(`Page count: ${pageCount} (from output/book-meta.json)`);
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} else {
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console.warn(`book-meta.json not found — using default page count ${pageCount}`);
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console.warn('Run `pnpm build` first for an accurate spine width.\n');
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}
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// Compute dimensions
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const spineWidth = pageCount * SPINE_PER_PAGE;
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const totalWidth = BLEED_IN + TRIM_W_IN + spineWidth + TRIM_W_IN + BLEED_IN;
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const totalHeight = BLEED_IN + TRIM_H_IN + BLEED_IN;
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console.log(`Spine width : ${spineWidth.toFixed(4)} in`);
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console.log(`Cover canvas: ${totalWidth.toFixed(4)} × ${totalHeight.toFixed(4)} in\n`);
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// Check for optional artwork files
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const frontImage = await fileExists(resolve(root, 'images/cover/front.png'))
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? '../images/cover/front.png' : null;
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const backImage = await fileExists(resolve(root, 'images/cover/back.png'))
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? '../images/cover/back.png' : null;
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// Render HTML from template
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const env = nunjucks.configure(resolve(root, 'templates'), { autoescape: false });
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const html = env.render('cover.html', {
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pageCount,
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spineWidth: spineWidth.toFixed(4),
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totalWidth: totalWidth.toFixed(4),
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totalHeight: totalHeight.toFixed(4),
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bleed: BLEED_IN,
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trimW: TRIM_W_IN,
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trimH: TRIM_H_IN,
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safe: SAFE_IN,
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spineSafe: SPINE_SAFE_IN,
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hasSpineText: pageCount >= MIN_SPINE_TEXT,
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frontImage,
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backImage,
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});
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const htmlOut = resolve(root, 'output', 'cover.html');
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await writeFile(htmlOut, html, 'utf-8');
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// Generate PDF
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const systemChromium = '/usr/bin/chromium';
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const useSystem = await fileExists(systemChromium);
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console.log(`Launching Puppeteer (${useSystem ? 'system Chromium' : 'bundled Chrome'})…`);
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const browser = await puppeteer.launch({
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headless: true,
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...(useSystem ? { executablePath: systemChromium } : {}),
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});
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const page = await browser.newPage();
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await page.goto(`file://${htmlOut}`, { waitUntil: 'networkidle0' });
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const pdfOut = resolve(root, 'output', 'cover.pdf');
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await page.pdf({
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path: pdfOut,
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width: `${totalWidth}in`,
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height: `${totalHeight}in`,
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printBackground: true,
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margin: { top: 0, bottom: 0, left: 0, right: 0 },
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});
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await browser.close();
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console.log('Cover PDF written to output/cover.pdf');
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console.log('\nNote: KDP recommends CMYK for covers. This PDF is RGB.');
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console.log('Convert with Adobe Acrobat or Ghostscript before upload if needed.');
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}
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generate().catch(err => { console.error(err); process.exit(1); });
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