add DICOM slice previews to image library

web_backend.py

@@ -16,10 +16,14 @@ from urllib.parse import parse_qs, unquote, urlparse
 
 os.environ.setdefault("MPLCONFIGDIR", "/tmp/head_ct_morph_matplotlib")
 
+import pydicom
+from PIL import Image
+
 from generate_head_extension_video import generate_video
 from head_extension_app import (
     APP_DIR,
     crop_head_neck,
+    ct_window,
     fit_image,
     load_dicom_volume,
     preview_deform_2d,
@@ -109,6 +113,54 @@ def list_library():
     return live_items
 
 
+def sort_key_for_dicom(path):
+    path = Path(path)
+    try:
+        ds = pydicom.dcmread(str(path), stop_before_pixels=True, force=True)
+        return (0, int(getattr(ds, "InstanceNumber", 0)), path.name)
+    except Exception:
+        stem = path.stem
+        return (1, int(stem) if stem.isdigit() else 0, path.name)
+
+
+def sorted_dicom_files(dicom_dir):
+    return sorted(Path(dicom_dir).glob("*.dcm"), key=sort_key_for_dicom)
+
+
+def find_library_item(item_id):
+    return next((item for item in list_library() if item["id"] == item_id), None)
+
+
+def make_library_slice_preview(item_id, index):
+    item = find_library_item(item_id)
+    if not item:
+        raise RuntimeError("影像库中没有找到该数据。")
+
+    dicom_files = sorted_dicom_files(item["dicomPath"])
+    if not dicom_files:
+        raise RuntimeError("该影像数据没有可预览的 .dcm 文件。")
+
+    count = len(dicom_files)
+    index = max(0, min(int(index), count - 1))
+    ds = pydicom.dcmread(str(dicom_files[index]), force=True)
+    image = ds.pixel_array.astype("float32")
+    image = image * float(getattr(ds, "RescaleSlope", 1))
+    image = image + float(getattr(ds, "RescaleIntercept", 0))
+
+    preview = Image.fromarray(ct_window(image)).convert("RGB")
+    preview = fit_image(preview, 720, 520)
+    canvas = BytesIO()
+    preview.save(canvas, format="PNG")
+    encoded = base64.b64encode(canvas.getvalue()).decode("ascii")
+    return {
+        "image": f"data:image/png;base64,{encoded}",
+        "index": index,
+        "count": count,
+        "file": dicom_files[index].name,
+        "patientId": item["patientId"],
+    }
+
+
 def parse_multipart(headers, body):
     content_type = headers.get("content-type", "")
     message = BytesParser(policy=default).parsebytes(
@@ -333,6 +385,13 @@ class Handler(BaseHTTPRequestHandler):
             self.send_json({"items": list_library()})
             return
 
+        if parsed.path == "/api/library/preview":
+            params = parse_qs(parsed.query)
+            item_id = params.get("id", [""])[0]
+            index = params.get("index", ["0"])[0]
+            self.send_json(make_library_slice_preview(item_id, index))
+            return
+
         if parsed.path == "/api/job":
             params = parse_qs(parsed.query)
             job_id = params.get("id", [""])[0]