Add DNG support v0.7

app/main.py

@@ -25,6 +25,7 @@ from fastapi.responses import FileResponse, Response
 from fastapi.staticfiles import StaticFiles
 from PIL import Image, ImageOps, UnidentifiedImageError
 from pillow_heif import register_heif_opener
+import rawpy
 
 register_heif_opener()
 
@@ -35,17 +36,21 @@ APP_SUBTITLE = (
     or "Local folder · in-place JPG, PNG, TIFF and HEIF metadata"
 )
 APP_URL = os.getenv("APP_URL", "http://localhost:8080")
-APP_VERSION = "0.6.1"
+APP_VERSION = "0.7.0"
 MAX_UPLOAD_MB = int(os.getenv("MAX_UPLOAD_MB", "150"))
 MAX_UPLOAD_BYTES = MAX_UPLOAD_MB * 1024 * 1024
 PREVIEW_MAX_EDGE = int(os.getenv("PREVIEW_MAX_EDGE", "2400"))
 PREVIEW_MAX_PIXELS = int(os.getenv("PREVIEW_MAX_PIXELS", "300000000"))
 Image.MAX_IMAGE_PIXELS = PREVIEW_MAX_PIXELS
 
-SUPPORTED_EXTENSIONS = {".jpg", ".jpeg", ".png", ".tif", ".tiff", ".heic", ".heif", ".hif"}
+SUPPORTED_EXTENSIONS = {
+    ".jpg", ".jpeg", ".png", ".tif", ".tiff",
+    ".heic", ".heif", ".hif", ".dng",
+}
 TIFF_EXTENSIONS = {".tif", ".tiff"}
 HEIF_EXTENSIONS = {".heic", ".heif", ".hif"}
-SERVER_PREVIEW_EXTENSIONS = TIFF_EXTENSIONS | HEIF_EXTENSIONS
+DNG_EXTENSIONS = {".dng"}
+SERVER_PREVIEW_EXTENSIONS = TIFF_EXTENSIONS | HEIF_EXTENSIONS | DNG_EXTENSIONS
 MEDIA_TYPES = {
     ".jpg": "image/jpeg",
     ".jpeg": "image/jpeg",
@@ -55,6 +60,7 @@ MEDIA_TYPES = {
     ".heic": "image/heic",
     ".heif": "image/heif",
     ".hif": "image/heif",
+    ".dng": "image/x-adobe-dng",
 }
 LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO").upper()
 
@@ -406,6 +412,8 @@ def _format_name(suffix: str) -> str:
         return "TIFF"
     if suffix in HEIF_EXTENSIONS:
         return "HEIF"
+    if suffix in DNG_EXTENSIONS:
+        return "DNG"
     return suffix.lstrip(".").upper() or "image"
 
 
@@ -429,6 +437,10 @@ def _validate_image_signature(path: Path, suffix: str) -> None:
             signature[offset:offset + 4] in hevc_brands
             for offset in range(8, len(signature) - 3, 4)
         )
+    elif suffix in DNG_EXTENSIONS:
+        # DNG is TIFF-based. ExifTool performs the deeper DNG structure
+        # validation when reading, extracting a preview, or writing metadata.
+        valid = signature.startswith((b"II*\x00", b"MM\x00*"))
 
     if not valid:
         raise HTTPException(
@@ -573,24 +585,77 @@ def _metadata_values(metadata: dict[str, Any]) -> tuple[bool, bool, dict[str, An
     return has_metadata, edited_by_app, values
 
 
+def _embedded_dng_preview(path: Path) -> Image.Image | None:
+    """Return the first usable DNG preview, preferring the largest common tags."""
+    for tag in ("JpgFromRaw", "PreviewImage", "ThumbnailImage"):
+        try:
+            completed = subprocess.run(
+                ["exiftool", "-b", f"-{tag}", "--", str(path)],
+                capture_output=True,
+                timeout=45,
+                check=False,
+            )
+        except subprocess.TimeoutExpired:
+            logger.warning("Timed out extracting DNG %s data.", tag)
+            continue
+        if completed.returncode != 0 or not completed.stdout:
+            continue
+        try:
+            with Image.open(io.BytesIO(completed.stdout)) as source:
+                source.load()
+                return source.copy()
+        except (UnidentifiedImageError, OSError, ValueError):
+            logger.debug("DNG %s data was not a usable image preview.", tag)
+    return None
+
+
+def _render_dng(path: Path) -> Image.Image:
+    """Render a half-size RGB fallback when a DNG has no embedded JPEG preview."""
+    try:
+        with rawpy.imread(str(path)) as raw:
+            width = int(raw.sizes.width)
+            height = int(raw.sizes.height)
+            if width <= 0 or height <= 0 or width * height > PREVIEW_MAX_PIXELS:
+                raise ValueError("DNG dimensions exceed the configured preview pixel limit.")
+            rgb = raw.postprocess(
+                use_camera_wb=True,
+                use_auto_wb=False,
+                no_auto_bright=False,
+                half_size=True,
+                output_bps=8,
+            )
+    except rawpy.LibRawError as exc:
+        raise ValueError("LibRaw could not decode this DNG.") from exc
+    return Image.fromarray(rgb)
+
+
 @app.post("/api/preview")
 async def create_preview(file: Annotated[UploadFile, File(...)]) -> Response:
-    """Generate a temporary browser-friendly preview for TIFF and HEIF images."""
+    """Generate a temporary browser-friendly preview for TIFF, HEIF, and DNG images."""
     filename = file.filename or "photo.tiff"
     suffix = Path(filename).suffix.lower()
     if suffix not in SERVER_PREVIEW_EXTENSIONS:
         raise HTTPException(
             status_code=415,
-            detail="Server-generated previews are only required for TIFF and HEIF files.",
+            detail="Server-generated previews are only required for TIFF, HEIF, and DNG files.",
         )
 
     with tempfile.TemporaryDirectory(prefix="photo-date-editor-preview-") as temp_dir:
         temp_path = Path(temp_dir) / f"source{suffix}"
         await _save_upload(file, temp_path, suffix)
         try:
-            with Image.open(temp_path) as source:
-                source.seek(0)
-                preview = ImageOps.exif_transpose(source)
+            if suffix in DNG_EXTENSIONS:
+                preview = _embedded_dng_preview(temp_path)
+                if preview is None:
+                    preview = _render_dng(temp_path)
+                preview = ImageOps.exif_transpose(preview)
+            else:
+                with Image.open(temp_path) as source:
+                    source.seek(0)
+                    preview = ImageOps.exif_transpose(source)
+                    preview.load()
+
+            try:
                 preview.thumbnail((PREVIEW_MAX_EDGE, PREVIEW_MAX_EDGE), Image.Resampling.LANCZOS)
 
                 if preview.mode in {"RGBA", "LA"} or (preview.mode == "P" and "transparency" in preview.info):
@@ -603,6 +668,8 @@ async def create_preview(file: Annotated[UploadFile, File(...)]) -> Response:
 
                 output = io.BytesIO()
                 preview.save(output, format="JPEG", quality=88, optimize=True)
+            finally:
+                preview.close()
         except (Image.DecompressionBombError, UnidentifiedImageError, OSError, ValueError) as exc:
             format_name = _format_name(suffix)
             logger.warning("%s preview generation failed for %s: %s", format_name, filename, exc)
@@ -625,7 +692,7 @@ async def read_metadata(file: Annotated[UploadFile, File(...)]) -> dict[str, boo
     if suffix not in SUPPORTED_EXTENSIONS:
         raise HTTPException(
             status_code=415,
-            detail="Supported formats are JPG, JPEG, PNG, TIF, TIFF, HEIC, HEIF, and HIF.",
+            detail="Supported formats are JPG, JPEG, PNG, TIF, TIFF, HEIC, HEIF, HIF, and DNG.",
         )
 
     with tempfile.TemporaryDirectory(prefix="photo-date-editor-read-") as temp_dir:
@@ -694,7 +761,7 @@ async def process_photo(
     if suffix not in SUPPORTED_EXTENSIONS:
         raise HTTPException(
             status_code=415,
-            detail="Supported formats are JPG, JPEG, PNG, TIF, TIFF, HEIC, HEIF, and HIF.",
+            detail="Supported formats are JPG, JPEG, PNG, TIF, TIFF, HEIC, HEIF, HIF, and DNG.",
         )
 
     exif_datetime, xmp_date, precision_label = _normalise_datetime(
@@ -726,7 +793,7 @@ async def process_photo(
         temp_path = Path(temp_dir) / f"working{suffix}"
         await _save_upload(file, temp_path, suffix)
 
-        supports_iptc = suffix in {".jpg", ".jpeg", ".tif", ".tiff"}
+        supports_iptc = suffix in {".jpg", ".jpeg", ".tif", ".tiff", ".dng"}
         command = [
             "exiftool",
             "-overwrite_original",