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photo_sorter/ui/image_viewer.py

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+from __future__ import annotations
+
+from pathlib import Path
+from typing import Optional
+
+from PyQt6.QtCore import Qt, QSize
+from PyQt6.QtGui import QPixmap, QImage
+from PyQt6.QtWidgets import QLabel, QVBoxLayout, QWidget
+
+try:
+    from PIL import Image, ExifTags  # type: ignore
+except Exception:  # Pillow ist optional
+    Image = None
+    ExifTags = None
+
+
+class ImageViewer(QWidget):
+    """Widget zur Anzeige eines Bildes, skaliert mit korrektem Seitenverhältnis."""
+
+    def __init__(self, parent: Optional[QWidget] = None) -> None:
+        super().__init__(parent)
+        self._original_pixmap: Optional[QPixmap] = None
+
+        self._label = QLabel(self)
+        self._label.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        self._label.setBackgroundRole(self._label.backgroundRole())
+        self._label.setScaledContents(False)
+
+        layout = QVBoxLayout(self)
+        layout.setContentsMargins(0, 0, 0, 0)
+        layout.addWidget(self._label)
+
+    def clear(self) -> None:
+        self._original_pixmap = None
+        self._label.clear()
+
+    def _load_pixmap_with_exif(self, path: Path) -> Optional[QPixmap]:
+        if Image is None:
+            pixmap = QPixmap(str(path))
+            return pixmap if not pixmap.isNull() else None
+
+        try:
+            img = Image.open(path)
+            # EXIF-Orientation anwenden, falls vorhanden
+            try:
+                exif = img._getexif()  # type: ignore[attr-defined]
+                if exif and ExifTags:
+                    orientation_key = next(
+                        (k for k, v in ExifTags.TAGS.items() if v == "Orientation"), None
+                    )
+                    if orientation_key and orientation_key in exif:
+                        orientation = exif[orientation_key]
+                        if orientation == 3:
+                            img = img.rotate(180, expand=True)
+                        elif orientation == 6:
+                            img = img.rotate(270, expand=True)
+                        elif orientation == 8:
+                            img = img.rotate(90, expand=True)
+            except Exception:
+                pass
+
+            img = img.convert("RGBA")
+            data = img.tobytes("raw", "RGBA")
+            qimg = QImage(
+                data,
+                img.width,
+                img.height,
+                QImage.Format.Format_RGBA8888,
+            )
+            pixmap = QPixmap.fromImage(qimg)
+            return pixmap
+        except Exception:
+            pixmap = QPixmap(str(path))
+            return pixmap if not pixmap.isNull() else None
+
+    def set_image(self, path: Optional[Path]) -> None:
+        if path is None:
+            self.clear()
+
+        if path is None:
+            return
+
+        pixmap = self._load_pixmap_with_exif(path)
+        if pixmap is None or pixmap.isNull():
+            self.clear()
+            return
+
+        self._original_pixmap = pixmap
+        self._update_scaled_pixmap()
+
+    def resizeEvent(self, event) -> None:  # type: ignore[override]
+        super().resizeEvent(event)
+        self._update_scaled_pixmap()
+
+    def _update_scaled_pixmap(self) -> None:
+        if self._original_pixmap is None:
+            return
+        target_size = self._label.size()
+        if not target_size.isValid():
+            return
+        scaled = self._original_pixmap.scaled(
+            target_size,
+            Qt.AspectRatioMode.KeepAspectRatio,
+            Qt.TransformationMode.SmoothTransformation,
+        )
+        self._label.setPixmap(scaled)