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@dataclass
class Tile:
tile_id: str
doc_id: str
source: str
kind: str
page: int
seq: int
y0: int
y1: int
path: str
ocr_text: str = ""
title: str = ""
def _doc_id_from_source(src: str) -> str:
tail = src.rstrip("/").split("/")[-1] or src
tail = re.sub(r".(html?|pdf|png|jpg)$", "", tail, flags=re.I)
return re.sub(r"[^A-Za-z0-9_.-()]+", "_", tail)[:80] or hashlib.md5(src.encode()).hexdigest()[:10]
def _ahash(img, size: int = 8) -> int:
"""64-bit average hash — cheap near-duplicate detection for repeated headers."""
import numpy as np
g = img.convert("L").resize((size, size))
a = np.asarray(g, dtype="float32")
bits = (a > a.mean()).flatten()
out = 0
for b in bits:
out = (out << 1) | int(b)
return out
def _hamming(a: int, b: int) -> int:
return bin(a ^ b).count("1")
def _is_informative(img, cfg: Config) -> bool:
"""Reject blank / solid-colour tiles before they ever reach the GPU."""
import numpy as np
a = np.asarray(img.convert("L"), dtype="float32")
return float(a.std()) >= cfg.blank_std_threshold
def _save_tile(img, out_dir: Path, name: str) -> str:
out_dir.mkdir(parents=True, exist_ok=True)
p = out_dir / f"{name}.png"
img.convert("RGB").save(p, format="PNG", optimize=True)
return str(p)
def slice_image_to_tiles(img, cfg: Config, *, doc_id: str, source: str, kind: str,
page: int, out_dir: Path, start_seq: int = 0,
seen_hashes: Optional[List[int]] = None,
title: str = "") -> List[Tile]:
"""Vertical sliding window with overlap. Used for PDFs and text fallback."""
from PIL import Image
seen_hashes = seen_hashes if seen_hashes is not None else []
W, H = img.size
if W != cfg.tile_width:
new_h = max(1, int(H * cfg.tile_width / W))
img = img.resize((cfg.tile_width, new_h))
W, H = img.size
step = max(1, cfg.tile_height - cfg.tile_overlap)
tiles: List[Tile] = []
y, seq = 0, start_seq
while y < H and (seq - start_seq) < cfg.max_tiles_per_doc:
h = min(cfg.tile_height, H - y)
if h < cfg.min_tile_height and seq > start_seq:
break
crop = img.crop((0, y, W, y + h))
if _is_informative(crop, cfg):
hsh = _ahash(crop)
if all(_hamming(hsh, s) > cfg.dedup_hamming for s in seen_hashes):
seen_hashes.append(hsh)
tid = f"{doc_id}__p{page}__t{seq}"
tiles.append(Tile(
tile_id=tid, doc_id=doc_id, source=source, kind=kind, page=page,
seq=seq, y0=y, y1=y + h, title=title,
path=_save_tile(crop, out_dir, tid),
))
seq += 1
y += step
return tiles
_JS_AUTOSCROLL = """
async () => {
await new Promise((resolve) => {
let y = 0;
const timer = setInterval(() => {
window.scrollBy(0, 800);
y += 800;
if (y >= document.body.scrollHeight || y > 40000) {
clearInterval(timer);
window.scrollTo(0, 0);
setTimeout(resolve, 250);
}
}, 40);
});
}
"""
_JS_FLATTEN = """
() => {
document.querySelectorAll('*').forEach((el) => {
const s = getComputedStyle(el);
if (s.position === 'fixed' || s.position === 'sticky') el.style.position = 'absolute';
});
document.querySelectorAll('[role="dialog"], .cookie, #cookie-banner, .cc-banner')
.forEach((el) => el.remove());
}
"""
_CSS_CLEANUP = """
* { animation: none !important; transition: none !important;
scroll-behavior: auto !important; }
html { -webkit-font-smoothing: antialiased; }
video, iframe[src*="youtube"] { visibility: hidden !important; }
"""
_UA = ("Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) "
"Chrome/124.0 Safari/537.36 PixelRAG-Tutorial/1.0")
async def _render_urls_async(urls: List[str], cfg: Config, out_dir: Path) -> List[Tile]:
from playwright.async_api import async_playwright
from PIL import Image
all_tiles: List[Tile] = []
async with async_playwright() as pw:
browser = await pw.chromium.launch(headless=True, args=cfg.headless_args)
ctx = await browser.new_context(
viewport={"width": cfg.tile_width, "height": cfg.tile_height},
device_scale_factor=cfg.device_scale,
user_agent=_UA,
java_script_enabled=True,
)
for url in urls:
doc_id = _doc_id_from_source(url)
page = await ctx.new_page()
try:
await page.goto(url, wait_until="domcontentloaded", timeout=cfg.nav_timeout_ms)
try:
await page.wait_for_load_state("networkidle", timeout=12000)
except Exception:
pass
await page.evaluate(_JS_AUTOSCROLL)
await page.add_style_tag(content=_CSS_CLEANUP)
await page.evaluate(_JS_FLATTEN)
title = (await page.title()) or doc_id
height = await page.evaluate(
"() => Math.max(document.body.scrollHeight, "
"document.documentElement.scrollHeight)")
height = int(min(height, cfg.max_page_height))
step = max(1, cfg.tile_height - cfg.tile_overlap)
seen: List[int] = []
y, seq = 0, 0
while y < height and seq < cfg.max_tiles_per_doc:
h = min(cfg.tile_height, height - y)
if h < cfg.min_tile_height and seq > 0:
break
buf = await page.screenshot(
full_page=True, type="png",
clip={"x": 0, "y": y, "width": cfg.tile_width, "height": h})
img = Image.open(io.BytesIO(buf)).convert("RGB")
if img.size[0] != cfg.tile_width:
img = img.resize((cfg.tile_width,
max(1, int(img.size[1] * cfg.tile_width / img.size[0]))))
if _is_informative(img, cfg):
hsh = _ahash(img)
if all(_hamming(hsh, s) > cfg.dedup_hamming for s in seen):
seen.append(hsh)
tid = f"{doc_id}__p0__t{seq}"
all_tiles.append(Tile(
tile_id=tid, doc_id=doc_id, source=url, kind="web",
page=0, seq=seq, y0=y, y1=y + h, title=title,
path=_save_tile(img, out_dir, tid)))
seq += 1
y += step
log.info(" rendered %-34s -> %2d tiles (page %dpx)", doc_id, seq, height)
except Exception as exc:
log.warning(" FAILED %s (%s)", url, type(exc).__name__)
finally:
await page.close()
await ctx.close()
await browser.close()
return all_tiles
def render_urls(urls: List[str], cfg: Config, out_dir: Path) -> List[Tile]:
"""Screenshot every URL into tiles; degrade to the text renderer on failure."""
try:
tiles = run_async(_render_urls_async(urls, cfg, out_dir))
if tiles:
return tiles
log.warning("Browser produced no tiles — using text-render fallback.")
except Exception as exc:
log.warning("Playwright unavailable (%s: %s) — using text-render fallback.",
type(exc).__name__, str(exc)[:160])
return [t for u in urls for t in render_url_as_text(u, cfg, out_dir)]
def _strip_html(html: str) -> str:
html = re.sub(r"(?is)<(script|style|nav|footer|header|noscript).*?</1>", " ", html)
html = re.sub(r"(?s)<!--.*?-->", " ", html)
html = re.sub(r"(?i)</(p|div|h[1-6]|li|tr|br)>", "n", html)
text = re.sub(r"(?s)<[^>]+>", " ", html)
for a, b in [(" ", " "), ("&", "&"), ("<", "<"), (">", ">"), (""", '"')]:
text = text.replace(a, b)
text = re.sub(r"[d+]", "", text)
text = re.sub(r"[ t]+", " ", text)
return re.sub(r"n{2,}", "n", text).strip()
def _mono_font(size: int = 20):
from PIL import ImageFont
for cand in ("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
"/usr/share/fonts/truetype/liberation/LiberationSans-Regular.ttf"):
if os.path.exists(cand):
return ImageFont.truetype(cand, size)
try:
import matplotlib.font_manager as fm
return ImageFont.truetype(fm.findfont("DejaVu Sans"), size)
except Exception:
return ImageFont.load_default()
def text_to_image(text: str, cfg: Config, title: str = "") -> Any:
"""Render plain text onto a tall white canvas — a browser-free stand-in."""
from PIL import Image, ImageDraw
font, tfont = _mono_font(20), _mono_font(30)
pad, lh, wrap = 40, 30, max(20, (cfg.tile_width - 80) // 11)
lines: List[str] = []
for para in text.split("n"):
para = para.strip()
if not para:
continue
while len(para) > wrap:
cut = para.rfind(" ", 0, wrap)
cut = cut if cut > 0 else wrap
lines.append(para[:cut])
para = para[cut:].lstrip()
lines.append(para)
lines = lines[:900]
height = pad * 2 + 60 + lh * len(lines)
img = Image.new("RGB", (cfg.tile_width, max(cfg.tile_height, height)), "white")
d = ImageDraw.Draw(img)
d.text((pad, pad), title[:60], font=tfont, fill=(15, 15, 15))
for i, ln in enumerate(lines):
d.text((pad, pad + 60 + i * lh), ln, font=font, fill=(35, 35, 35))
return img
def render_url_as_text(url: str, cfg: Config, out_dir: Path) -> List[Tile]:
import requests
doc_id = _doc_id_from_source(url)
try:
r = requests.get(url, timeout=30, headers={"User-Agent": _UA})
r.raise_for_status()
body = _strip_html(r.text)
m = re.search(r"(?is)<title>(.*?)</title>", r.text)
title = m.group(1).strip() if m else doc_id
except Exception as exc:
log.warning(" fetch failed for %s (%s)", url, type(exc).__name__)
return []
img = text_to_image(body, cfg, title=title)
log.info(" text-rendered %-30s -> canvas %dpx", doc_id, img.size[1])
return slice_image_to_tiles(img, cfg, doc_id=doc_id, source=url, kind="text",
page=0, out_dir=out_dir, title=title)
def render_pdf(pdf_path: str, cfg: Config, out_dir: Path, dpi: int = 150) -> List[Tile]:
import fitz
from PIL import Image
doc_id = _doc_id_from_source(pdf_path)
tiles: List[Tile] = []
with fitz.open(pdf_path) as doc:
title = (doc.metadata or {}).get("title") or doc_id
n_pages = doc.page_count
for pno in range(n_pages):
pix = doc[pno].get_pixmap(dpi=dpi)
img = Image.frombytes("RGB", (pix.width, pix.height), pix.samples)
tiles += slice_image_to_tiles(img, cfg, doc_id=doc_id, source=pdf_path,
kind="pdf", page=pno, out_dir=out_dir,
title=title)
log.info(" rendered %-34s -> %2d tiles (%d pages)", doc_id, len(tiles), n_pages)
return tiles
def make_synthetic_pdf(path: Path) -> str:
"""A tiny PDF so the tutorial always exercises the PDF path, offline or not."""
import fitz
body = [
("PixelRAG Internal Note", 22),
("", 12),
("Why pixel-native retrieval?", 16),
("Parsers are per-site glue code. A renderer is one code path for every", 11),
("document type: HTML, PDF, scanned fax, spreadsheet export, dashboard.", 11),
("", 11),
("Tiling policy", 16),
("Tiles are 1024x1024 with 128px of vertical overlap. Overlap keeps a", 11),
("sentence or table row from being split across two embeddings, which is", 11),
("the single biggest source of recall loss in naive screenshot pipelines.", 11),
("", 11),
("Serving", 16),
("FAISS inner-product over L2-normalised vectors equals cosine similarity.", 11),
("Tile scores are max-pooled per document so one strong tile can surface", 11),
("a long page, mirroring late-interaction retrieval behaviour.", 11),
("", 11),
("The mitochondria reference is a joke; the overlap advice is not.", 11),
]
doc = fitz.open()
page = doc.new_page()
y = 72
for line, size in body:
page.insert_text((72, y), line, fontsize=size, fontname="helv")
y += size + 8
doc.save(str(path))
doc.close()
return str(path)
