Toju/tools/generate-android-app-icons.mjs

#!/usr/bin/env node
// Regenerates the Android launcher icons (adaptive + legacy) and splash screens
// for the Capacitor shell from the brand icon. Run with `npm run cap:assets:android`.
//
// Source of truth: images/icon-new-rounded.png (circular brand mark on a purple disc).
// Output: toju-app/android/app/src/main/res/{mipmap-*,drawable*,values}.
//
// The brand background colour and required output set are mirrored by
// toju-app/src/app/infrastructure/mobile/logic/mobile-android-launcher-icon.rules.ts,
// which the Vitest suite asserts against.

import { mkdir, writeFile } from 'node:fs/promises';
import { dirname, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

import sharp from 'sharp';

const REPO_ROOT = resolve(dirname(fileURLToPath(import.meta.url)), '..');
const SOURCE_ICON = resolve(REPO_ROOT, 'images/icon-new-rounded.png');
const RES_DIR = resolve(REPO_ROOT, 'toju-app/android/app/src/main/res');

/** Brand purple sampled from the brand icon disc. Keep in sync with the rules file. */
const BRAND_BACKGROUND = { r: 74, g: 33, b: 122 };
const BRAND_BACKGROUND_HEX = '#4A217A';

/** Adaptive-icon safe zone (66dp inside 108dp). Keep in sync with the rules file. */
const ADAPTIVE_FOREGROUND_ICON_RATIO = 66 / 108;
const LEGACY_LAUNCHER_ICON_RATIO = ADAPTIVE_FOREGROUND_ICON_RATIO;
const SPLASH_ICON_RATIO = 0.32;

/** Legacy square/round launcher bitmap edge length per density. */
const LEGACY_ICON_PX = { mdpi: 48, hdpi: 72, xhdpi: 96, xxhdpi: 144, xxxhdpi: 192 };

/** Adaptive foreground canvas edge length per density (108dp). */
const FOREGROUND_PX = { mdpi: 108, hdpi: 162, xhdpi: 216, xxhdpi: 324, xxxhdpi: 432 };

/** Portrait splash dimensions per density; landscape swaps width/height. */
const SPLASH_PORTRAIT = {
  mdpi: [320, 480],
  hdpi: [480, 800],
  xhdpi: [720, 1280],
  xxhdpi: [960, 1600],
  xxxhdpi: [1280, 1920]
};

async function ensureDir(filePath) {
  await mkdir(dirname(filePath), { recursive: true });
}

async function writePng(buffer, resRelativePath) {
  const outPath = resolve(RES_DIR, resRelativePath);
  await ensureDir(outPath);
  await writeFile(outPath, buffer);
  return resRelativePath;
}

/** Resize the circular brand icon to a square of `size` px, preserving transparent corners. */
async function squareIcon(size) {
  return sharp(SOURCE_ICON).resize(size, size, { fit: 'contain', background: { r: 0, g: 0, b: 0, alpha: 0 } }).png().toBuffer();
}

/** Compose the brand icon centred at `iconRatio` of the canvas over a solid background. */
async function centeredIconOnBackground(width, height, iconRatio, background) {
  const iconSize = Math.round(Math.min(width, height) * iconRatio);
  const icon = await squareIcon(iconSize);

  return sharp({ create: { width, height, channels: 4, background } })
    .composite([{ input: icon, gravity: 'center' }])
    .png()
    .toBuffer();
}

/** Compose the brand icon centred on a transparent canvas for adaptive foreground layers. */
async function centeredIconOnTransparentCanvas(canvasSize, iconRatio) {
  const iconSize = Math.round(canvasSize * iconRatio);
  const icon = await squareIcon(iconSize);

  return sharp({
    create: {
      width: canvasSize,
      height: canvasSize,
      channels: 4,
      background: { r: 0, g: 0, b: 0, alpha: 0 }
    }
  })
    .composite([{ input: icon, gravity: 'center' }])
    .png()
    .toBuffer();
}

async function generateLauncherIcons() {
  const written = [];

  for (const [density, size] of Object.entries(LEGACY_ICON_PX)) {
    const background = { ...BRAND_BACKGROUND, alpha: 1 };
    const bitmap = await centeredIconOnBackground(size, size, LEGACY_LAUNCHER_ICON_RATIO, background);
    written.push(await writePng(bitmap, `mipmap-${density}/ic_launcher.png`));
    written.push(await writePng(bitmap, `mipmap-${density}/ic_launcher_round.png`));
  }

  for (const [density, size] of Object.entries(FOREGROUND_PX)) {
    const foreground = await centeredIconOnTransparentCanvas(size, ADAPTIVE_FOREGROUND_ICON_RATIO);
    written.push(await writePng(foreground, `mipmap-${density}/ic_launcher_foreground.png`));
  }

  return written;
}

async function generateAdaptiveBackgroundColor() {
  const xml = `<?xml version="1.0" encoding="utf-8"?>\n<resources>\n    <color name="ic_launcher_background">${BRAND_BACKGROUND_HEX}</color>\n</resources>\n`;
  const outPath = resolve(RES_DIR, 'values/ic_launcher_background.xml');
  await writeFile(outPath, xml);
  return 'values/ic_launcher_background.xml';
}

async function generateSplashScreens() {
  const written = [];
  const background = { ...BRAND_BACKGROUND, alpha: 1 };

  for (const [density, [portW, portH]] of Object.entries(SPLASH_PORTRAIT)) {
    const portrait = await centeredIconOnBackground(portW, portH, SPLASH_ICON_RATIO, background);
    const landscape = await centeredIconOnBackground(portH, portW, SPLASH_ICON_RATIO, background);
    written.push(await writePng(portrait, `drawable-port-${density}/splash.png`));
    written.push(await writePng(landscape, `drawable-land-${density}/splash.png`));
  }

  const base = await centeredIconOnBackground(480, 320, SPLASH_ICON_RATIO, background);
  written.push(await writePng(base, 'drawable/splash.png'));

  return written;
}

async function main() {
  const written = [
    ...(await generateLauncherIcons()),
    await generateAdaptiveBackgroundColor(),
    ...(await generateSplashScreens())
  ];

  console.log(`Generated ${written.length} Android brand resources from ${SOURCE_ICON}:`);
  for (const file of written) {
    console.log(`  res/${file}`);
  }
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});