Fix slideshow video sizing, revert video hide

- Slideshow video player: auto_size_video=False, no height constraint
- Revert video widget hide/show (caused info panel issues)
- Preview video still auto-sizes to aspect ratio

booru_viewer/gui/preview.py

@@ -94,6 +94,7 @@ class FullscreenPreview(QMainWindow):
         self._stack.addWidget(self._viewer)
 
         self._video = VideoPlayer()
+        self._video._auto_size_video = False  # fullscreen — don't constrain height
         self._video.play_next.connect(lambda: self.navigate.emit(1))
         self._stack.addWidget(self._video)
 
@@ -485,7 +486,6 @@ class VideoPlayer(QWidget):
         self._ended = False
         self._video_sized = False
         self._video_widget.setMaximumHeight(16777215)
-        self._video_widget.hide()  # hide until first frame to prevent black flash
         self._last_pos = 0
         self._player.setLoops(QMediaPlayer.Loops.Infinite)
         self._player.setSource(QUrl.fromLocalFile(path))
@@ -562,18 +562,20 @@ class VideoPlayer(QWidget):
         else:
             self._play_btn.setText("Play")
 
+    _auto_size_video = True  # set False for fullscreen/slideshow
+
     def _on_video_size(self, frame) -> None:
         """Resize video widget to match video aspect ratio on first frame."""
         if self._video_sized or not frame.isValid():
             return
         self._video_sized = True
+        if self._auto_size_video:
             vw = frame.size().width()
             vh = frame.size().height()
             if vw > 0 and vh > 0:
                 available_w = self._video_widget.parentWidget().width() if self._video_widget.parentWidget() else self._video_widget.width()
                 scaled_h = int(available_w * vh / vw)
                 self._video_widget.setMaximumHeight(scaled_h)
-        self._video_widget.show()
 
     def _on_media_status(self, status) -> None:
         pass