Initial commit: snapAna 截图智能整理工具

包含 FastAPI 后端、React 前端、队列/OCR/标签/待办等完整功能。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/thumbnail.py

@@ -0,0 +1,48 @@
+"""生成并缓存缩略图。"""
+from __future__ import annotations
+
+import hashlib
+from pathlib import Path
+
+from PIL import Image
+
+from app.core.config import settings
+from app.core.path_utils import path_to_storage
+
+
+SUPPORTED_EXTS = {".png", ".jpg", ".jpeg", ".webp", ".gif", ".bmp", ".tif", ".tiff"}
+
+
+def is_supported(path: Path) -> bool:
+    """是否为我们支持的图片格式。"""
+    return path.suffix.lower() in SUPPORTED_EXTS
+
+
+def generate_thumbnail(image_path: Path, max_side: int | None = None) -> Path:
+    """生成 webp 缩略图，落到缓存目录。返回缓存路径。"""
+    max_side = max_side or settings.thumb_size
+    # 用文件路径 + mtime 哈希作为缓存键，源文件变化会自动生成新缩略图
+    stat = image_path.stat()
+    key = hashlib.md5(
+        f"{path_to_storage(image_path)}|{stat.st_mtime_ns}|{max_side}".encode("utf-8")
+    ).hexdigest()
+    out = settings.thumb_dir / f"{key}.webp"
+    if out.exists():
+        return out
+    with Image.open(image_path) as img:
+        img = img.convert("RGB")
+        img.thumbnail((max_side, max_side), Image.LANCZOS)
+        img.save(out, format="WEBP", quality=80)
+    return out
+
+
+def file_hash(image_path: Path, chunk: int = 1024 * 1024) -> str:
+    """计算文件 sha256，用作去重键。"""
+    h = hashlib.sha256()
+    with open(image_path, "rb") as f:
+        while True:
+            data = f.read(chunk)
+            if not data:
+                break
+            h.update(data)
+    return h.hexdigest()