fix

loop_labeler_ui.py

@@ -108,9 +108,10 @@ class LoopLabeler(QWidget):
         start = candidate["start"]
         end = candidate["end"]
         nframes = len(self.frames)
+        # Set both sliders to cover full range from 0 to N
         self.start_slider.setMinimum(0)
-        self.start_slider.setMaximum(nframes-2 if nframes > 1 else 0)
-        self.end_slider.setMinimum(start+1)
+        self.start_slider.setMaximum(nframes-1 if nframes > 0 else 0)
+        self.end_slider.setMinimum(0)
         self.end_slider.setMaximum(nframes-1 if nframes > 0 else 0)
         self.start_slider.setValue(start)
         self.end_slider.setValue(end)
@@ -120,27 +121,46 @@ class LoopLabeler(QWidget):
     def on_slider_changed(self):
         start = self.start_slider.value()
         end = self.end_slider.value()
-        # Always keep end > start
-        self.end_slider.setMinimum(start+1)
+        # Ensure valid start and end values for preview
+        # We'll allow any values but for preview we need end > start
         if end <= start:
-            end = start + 1
-            self.end_slider.setValue(end)
+            # For preview purposes, we'll adjust temporarily in the update_preview method
+            pass
         self.preview_idx = 0
 
     def update_preview(self):
         start = self.start_slider.value()
         end = self.end_slider.value()
-        if self.frames and end > start:
-            frame = self.frames[start + (self.preview_idx % (end-start))]
+        
+        # Handle case where end ≤ start by showing a single frame or appropriate range
+        if self.frames:
+            if end <= start:
+                # Show just the start frame when end <= start
+                frame_idx = start
+                frame = self.frames[frame_idx]
+                show_progress = False
+            else:
+                # Normal case: show animation between start and end
+                frame_idx = start + (self.preview_idx % (end-start))
+                frame = self.frames[frame_idx]
+                show_progress = True
+                
             import numpy as np
             import cv2
             frame_resized = frame.resize((320,320))
             arr = np.array(frame_resized)
             # Draw progress indicator line at bottom
             indicator_height = 2
-            total = end - start
-            pos = self.preview_idx % total
-            bar_w = int(320 * (pos / max(total-1, 1)))
+            
+            # Only show progress bar when we have a valid range
+            if show_progress:
+                total = end - start
+                pos = self.preview_idx % total
+                bar_w = int(320 * (pos / max(total-1, 1)))
+            else:
+                # Just show a full bar for single frame
+                bar_w = 320
+                
             arr[-indicator_height:, :320] = [220, 220, 220]  # light gray background
             arr[-indicator_height:, :bar_w] = [100, 100, 255]    # red progress
             # Convert RGB to BGR for OpenCV, then to QImage