Enhance video editing controls: add Shift+scroll functionality to expand/contract crop uniformly and implement adjust_crop_size_uniform method

croppa/main.py

@@ -4025,7 +4025,7 @@ class VideoEditor:
                 # Force immediate display update to recalculate previous/next points and arrows
                 self.display_current_frame()
 
-        # Handle scroll wheel: Ctrl+scroll -> zoom; plain scroll -> seek ±1 frame (independent of multiplier)
+        # Handle scroll wheel: Ctrl+scroll -> zoom; Shift+scroll -> expand/contract crop; plain scroll -> seek ±1 frame
         if event == cv2.EVENT_MOUSEWHEEL:
             if flags & cv2.EVENT_FLAG_CTRLKEY:
                 if flags > 0:  # Scroll up -> zoom in
@@ -4033,6 +4033,12 @@ class VideoEditor:
                 else:  # Scroll down -> zoom out
                     self.zoom_factor = max(self.MIN_ZOOM, self.zoom_factor - self.ZOOM_INCREMENT)
                 self.clear_transformation_cache()
+            elif flags & cv2.EVENT_FLAG_SHIFTKEY:
+                # Shift+scroll -> expand/contract crop uniformly
+                if flags > 0:  # Scroll up -> expand
+                    self.adjust_crop_size_uniform(expand=True)
+                else:  # Scroll down -> contract
+                    self.adjust_crop_size_uniform(expand=False)
             else:
                 if not self.is_image_mode:
                     direction = 1 if flags > 0 else -1
@@ -4265,6 +4271,45 @@ class VideoEditor:
         self.clear_transformation_cache()
         self.save_state()  # Save state when crop is adjusted
 
+    def adjust_crop_size_uniform(self, expand: bool, amount: int = None):
+        """Expand or contract crop uniformly in all directions
+        expand=False: expand (like uppercase HJKL)
+        expand=True: contract (like lowercase hjkl)
+        """
+        if amount is None:
+            amount = self.crop_size_step
+        if not self.crop_rect:
+            center_x = self.frame_width // 2
+            center_y = self.frame_height // 2
+            default_size = min(self.frame_width, self.frame_height) // 4
+            self.crop_rect = (
+                center_x - default_size // 2,
+                center_y - default_size // 2,
+                default_size,
+                default_size
+            )
+            return
+
+        x, y, w, h = self.crop_rect
+
+        if not expand:  # expand=False means expand
+            # Expand uniformly from center
+            new_x = max(0, x - amount)
+            new_y = max(0, y - amount)
+            new_w = min(self.frame_width - new_x, w + (x - new_x) + amount)
+            new_h = min(self.frame_height - new_y, h + (y - new_y) + amount)
+        else:  # expand=True means contract
+            # Contract uniformly toward center
+            contract_amount = min(amount, (w - 10) // 2, (h - 10) // 2)
+            new_x = x + contract_amount
+            new_y = y + contract_amount
+            new_w = max(10, w - contract_amount * 2)
+            new_h = max(10, h - contract_amount * 2)
+
+        self.crop_rect = (new_x, new_y, new_w, new_h)
+        self.clear_transformation_cache()
+        self.save_state()
+
     def render_video(self, output_path: str):
         """Render video or save image with current edits applied"""
         if self.is_image_mode: