RUWIO/scripts/verify-capture.cjs

// Phase A verification harness (05_electron-rendering-integration-plan_2.md, finding #1/#2).
//
// Reproduces renderWorker.cts's window-creation + capturePage path against a
// scene with one moving + fading layer, then checks that captured frames are
// (a) non-blank and (b) actually advance over time. This validates or refutes
// "capturePage on a hidden, non-offscreen window returns blank/stale frames".
//
// Run: node_modules/.bin/electron scripts/verify-capture.cjs
// Set OFFSCREEN=1 to exercise the offscreen+paint-settle code path instead.

const { app, BrowserWindow } = require('electron')
const path = require('node:path')
const { pathToFileURL } = require('node:url')

const OFFSCREEN = process.env.OFFSCREEN === '1'

// A 320x240 scene: a red rect slides left->right and fades over 2s on a dark bg.
const scene = {
  canvas: { width: 320, height: 240, background: '#202030' },
  duration: 2,
  assets: [{ id: 'a1', kind: 'rect', width: 40, height: 40, fill: '#ff4040' }],
  layers: [
    {
      id: 'l1',
      assetId: 'a1',
      visible: true,
      base: { x: 20, y: 100, scaleX: 1, scaleY: 1, rotation: 0, opacity: 1 },
      keyframes: [
        { time: 0, props: { x: 20 } },
        { time: 2, props: { x: 260 } },
      ],
    },
  ],
}

function createRenderWindow() {
  return new BrowserWindow({
    width: scene.canvas.width,
    height: scene.canvas.height,
    show: false,
    frame: false,
    transparent: true,
    backgroundColor: '#00000000',
    webPreferences: {
      contextIsolation: true,
      nodeIntegration: false,
      sandbox: true,
      offscreen: OFFSCREEN,
    },
  })
}

// Cheap fingerprint of a NativeImage: total pixels, count of non-(near)background
// pixels, and a coarse sum so we can tell frames apart.
function fingerprint(image) {
  const bmp = image.getBitmap() // BGRA
  let nonBg = 0
  let redish = 0
  // Position-weighted hash: changes under pure translation (an order-independent
  // sum would not), so two frames that differ only in where the rect sits hash
  // differently.
  let hash = 0
  for (let i = 0; i < bmp.length; i += 4) {
    const b = bmp[i]
    const g = bmp[i + 1]
    const r = bmp[i + 2]
    const px = i / 4
    if (Math.abs(r - 0x20) + Math.abs(g - 0x20) + Math.abs(b - 0x30) > 60) nonBg++
    if (r > 150 && g < 120 && b < 120) {
      redish++
      hash = (hash + px * 2654435761) >>> 0
    }
  }
  return { pixels: bmp.length / 4, nonBg, redish, hash, size: image.getSize() }
}

async function main() {
  const win = createRenderWindow()
  win.webContents.setWindowOpenHandler(() => ({ action: 'deny' }))

  const renderHtml = path.join(process.cwd(), 'server', 'render.html')
  await win.loadURL(pathToFileURL(renderHtml).toString())
  await win.webContents.executeJavaScript(`window.__animatrInit(${JSON.stringify(scene)})`, true)

  const captureRect = { x: 0, y: 0, width: scene.canvas.width, height: scene.canvas.height }
  const times = [0, 0.5, 1, 1.5, 2]
  const frames = []

  for (const t of times) {
    // __animatrSeek now resolves only after a compositor paint settle, so the
    // worker just awaits it — no extra settle here (mirrors renderWorker.cts).
    await win.webContents.executeJavaScript(`window.__animatrSeek(${t})`, true)
    const image = await win.webContents.capturePage(captureRect)
    frames.push({ t, ...fingerprint(image) })
  }

  // Analysis
  let pass = true
  const notes = []
  for (const f of frames) {
    if (f.size.width !== scene.canvas.width || f.size.height !== scene.canvas.height) {
      pass = false
      notes.push(`frame t=${f.t}: wrong size ${f.size.width}x${f.size.height}`)
    }
    if (f.nonBg < 50) {
      pass = false
      notes.push(`frame t=${f.t}: looks blank (nonBg=${f.nonBg})`)
    }
  }
  // Frames must differ (motion advanced, not frozen on frame 0).
  const hashes = new Set(frames.map((f) => f.hash))
  if (hashes.size < frames.length) {
    pass = false
    notes.push(`frames not all distinct: ${frames.length} captured, ${hashes.size} unique hashes`)
  }

  console.log('OFFSCREEN =', OFFSCREEN)
  console.log('captures:')
  for (const f of frames) {
    console.log(
      `  t=${f.t}  nonBg=${f.nonBg}  redish=${f.redish}  hash=${f.hash}  size=${f.size.width}x${f.size.height}`,
    )
  }
  console.log(notes.length ? 'NOTES:\n  ' + notes.join('\n  ') : 'NOTES: none')
  console.log(pass ? 'RESULT: PASS' : 'RESULT: FAIL')

  if (!win.isDestroyed()) win.close()
  app.exit(pass ? 0 : 1)
}

app.on('window-all-closed', () => {})

app.whenReady().then(() =>
  main().catch((err) => {
    console.error('HARNESS ERROR:', err)
    app.exit(2)
  }),
)