Add caching for video transformations to improve performance during auto-repeat seeking

???

croppa/main.py

@@ -151,6 +151,11 @@ class VideoEditor:
         # Display optimization - track when redraw is needed
         self.display_needs_update = True
         self.last_display_state = None
+        
+        # Cached transformations for performance
+        self.cached_transformed_frame = None
+        self.cached_frame_number = None
+        self.cached_transform_hash = None
 
     def _get_state_file_path(self) -> Path:
         """Get the state file path for the current media file"""
@@ -660,13 +665,29 @@ class VideoEditor:
         if frame is None:
             return None
 
+        # Create a hash of the transformation parameters for caching
+        transform_hash = hash((
+            self.crop_rect,
+            self.zoom_factor,
+            self.rotation_angle,
+            self.brightness,
+            self.contrast,
+            self.display_offset
+        ))
+
+        # Check if we can use cached transformation during auto-repeat seeking
+        if (self.auto_repeat_active and 
+            self.cached_transformed_frame is not None and
+            self.cached_frame_number == self.current_frame and
+            self.cached_transform_hash == transform_hash):
+            return self.cached_transformed_frame.copy()
+
         # Work in-place when possible to avoid unnecessary copying
         processed_frame = frame
 
         # Apply brightness/contrast first (to original frame for best quality)
         processed_frame = self.apply_brightness_contrast(processed_frame)
 
-
         # Apply crop
         if self.crop_rect:
             x, y, w, h = self.crop_rect
@@ -701,8 +722,20 @@ class VideoEditor:
                 end_y = min(new_height, start_y + self.window_height)
                 processed_frame = processed_frame[start_y:end_y, start_x:end_x]
 
+        # Cache the result for auto-repeat seeking performance
+        if self.auto_repeat_active:
+            self.cached_transformed_frame = processed_frame.copy()
+            self.cached_frame_number = self.current_frame
+            self.cached_transform_hash = transform_hash
+
         return processed_frame
 
+    def clear_transformation_cache(self):
+        """Clear the cached transformation to force recalculation"""
+        self.cached_transformed_frame = None
+        self.cached_frame_number = None
+        self.cached_transform_hash = None
+
     def apply_rotation(self, frame):
         """Apply rotation to frame"""
         if self.rotation_angle == 0:
@@ -718,6 +751,7 @@ class VideoEditor:
     def rotate_clockwise(self):
         """Rotate video 90 degrees clockwise"""
         self.rotation_angle = (self.rotation_angle + 90) % 360
+        self.clear_transformation_cache()
 
     def apply_brightness_contrast(self, frame):
         """Apply brightness and contrast adjustments to frame"""
@@ -736,11 +770,13 @@ class VideoEditor:
     def adjust_brightness(self, delta: int):
         """Adjust brightness by delta (-100 to 100)"""
         self.brightness = max(-100, min(100, self.brightness + delta))
+        self.clear_transformation_cache()
         self.display_needs_update = True
 
     def adjust_contrast(self, delta: float):
         """Adjust contrast by delta (0.1 to 3.0)"""
         self.contrast = max(0.1, min(3.0, self.contrast + delta))
+        self.clear_transformation_cache()
         self.display_needs_update = True
 
     def show_progress_bar(self, text: str = "Processing..."):
@@ -1326,6 +1362,7 @@ class VideoEditor:
                     self.zoom_factor = max(
                         self.MIN_ZOOM, self.zoom_factor - self.ZOOM_INCREMENT
                     )
+                self.clear_transformation_cache()
 
     def set_crop_from_screen_coords(self, screen_rect):
         """Convert screen coordinates to video frame coordinates and set crop"""
@@ -1445,6 +1482,7 @@ class VideoEditor:
             if self.crop_rect:
                 self.crop_history.append(self.crop_rect)
             self.crop_rect = (original_x, original_y, original_w, original_h)
+            self.clear_transformation_cache()
             self.save_state()  # Save state when crop is set
 
     def seek_to_timeline_position(self, mouse_x, bar_x_start, bar_width):
@@ -1460,6 +1498,7 @@ class VideoEditor:
             self.crop_rect = self.crop_history.pop()
         else:
             self.crop_rect = None
+        self.clear_transformation_cache()
         self.save_state()  # Save state when crop is undone
 
     def toggle_marker_looping(self):
@@ -1557,6 +1596,7 @@ class VideoEditor:
                 new_w = w - amount
                 self.crop_rect = (new_x, y, new_w, h)
 
+        self.clear_transformation_cache()
         self.save_state()  # Save state when crop is adjusted
 
     def render_video(self, output_path: str):
@@ -2170,6 +2210,7 @@ class VideoEditor:
                     self.crop_history.append(self.crop_rect)
                 self.crop_rect = None
                 self.zoom_factor = 1.0
+                self.clear_transformation_cache()
                 self.save_state()  # Save state when crop is cleared
             elif key == ord("1"):
                 # Cut markers only for videos