@appsemble/node-utils/icon.js

NodeJS utilities used by Appsemble internally.

import sharp from 'sharp';
import { readAsset } from './readAsset.js';
/**
 * A transparent background color used by sharp.
 */
const transparent = { r: 0, g: 0, b: 0, alpha: 0 };
/**
 * The diameter of the safe area for maskable icons.
 *
 * https://css-tricks.com/maskable-icons-android-maskable-icons-for-your-pwa/
 */
const safeAreaDiameter = 0.8;
export async function serveIcon(ctx, { background, cache, fallback, height, icon, maskable, maskableIcon, raw, width, }) {
    const buffer = (maskable && maskableIcon) || icon || (await readAsset(fallback));
    let img = sharp(buffer);
    if (raw) {
        const { format } = await img.metadata();
        ctx.body = buffer;
        // @ts-expect-error 2322 null is not assignable to type (strictNullChecks)
        ctx.type = format;
        return;
    }
    if (!maskable) {
        // Serve the regular app icon, but scaled.
        img.resize({
            width,
            height,
            fit: 'contain',
            background: background || transparent,
        });
        if (background) {
            img.flatten({ background });
        }
    }
    else if (maskableIcon) {
        img.resize({ width, height, fit: 'cover' });
        if (background) {
            img.flatten({ background });
        }
    }
    else {
        // Make the regular icon maskable
        const actual = img;
        const metadata = await actual.metadata();
        // @ts-expect-error 18048 variable is possibly undefined (strictNullChecks)
        const angle = Math.atan(metadata.height / metadata.width);
        actual.resize({
            // @ts-expect-error 18048 variable is possibly undefined (strictNullChecks)
            width: Math.ceil(Math.cos(angle) * safeAreaDiameter * width),
            // By leaving out height, libvips will determine this for us. This has better precision than
            // calculating this using JavasScript and passing it manually.
            // height: Math.ceil(Math.sin(angle) * safeAreaDiameter * size),
            fit: 'contain',
            background,
        });
        // @ts-expect-error 18048 variable is possibly undefined (strictNullChecks)
        img = sharp(Buffer.alloc(width * height * 4, 0), {
            // @ts-expect-error 2322 null is not assignable to type (strictNullChecks)
            raw: { width, height, channels: 4 },
        });
        img.resize({ width, height });
        img.composite([{ input: await actual.toFormat('png').toBuffer() }]);
        if (background) {
            img.flatten({ background });
        }
        // Cache app icons for 1 week.
        if (cache) {
            ctx.set('cache-control', `public, max-age=${60 * 60 * 24 * 7},immutable`);
        }
    }
    ctx.body = await img.toFormat('png').toBuffer();
    ctx.type = 'image/png';
}
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