fix: improve TUI with View buttons and smooth out blur interpolation

src/faceblur/app.py

@@ -337,6 +337,16 @@ class FaceSelectionScreen(Screen):
     .face-row {
         height: 3;
         margin-bottom: 0;
+        align: left middle;
+    }
+
+    .face-checkbox {
+        width: 80%;
+    }
+
+    .view-btn {
+        min-width: 8;
+        margin-left: 2;
     }
 
     #blur-method-label {
@@ -391,13 +401,21 @@ class FaceSelectionScreen(Screen):
                             sample_info = (
                                 f"  [dim]{self.face_samples[cluster.id]}[/dim]"
                             )
+                        with Horizontal(classes="face-row"):
                             yield Checkbox(
                                 f"Person {cluster.id + 1}  "
                                 f"({len(cluster.faces)} detections)"
                                 f"{sample_info}",
                                 value=True,
                                 id=f"cluster-{cluster.id}",
-                            classes="face-row",
+                                classes="face-checkbox",
+                            )
+                            if cluster.id in self.face_samples:
+                                yield Button(
+                                    "View",
+                                    id=f"view-{cluster.id}",
+                                    variant="default",
+                                    classes="view-btn",
                                 )
                     yield Label("Blur method:", id="blur-method-label")
                     yield Select(
@@ -424,6 +442,25 @@ class FaceSelectionScreen(Screen):
             self.app.pop_screen()
         elif event.button.id == "blur-btn":
             self._start_encoding()
+        elif event.button.id and event.button.id.startswith("view-"):
+            cluster_id = int(event.button.id.split("-")[1])
+            if cluster_id in self.face_samples:
+                self._open_image(self.face_samples[cluster_id])
+
+    def _open_image(self, path: Path) -> None:
+        """Open image in default viewer."""
+        import subprocess
+        import sys
+
+        try:
+            if sys.platform == "darwin":
+                subprocess.run(["open", str(path)])
+            elif sys.platform == "win32":
+                os.startfile(str(path))
+            else:
+                subprocess.run(["xdg-open", str(path)])
+        except Exception:
+            pass  # Ignore if viewer fails to launch
 
     def _start_encoding(self) -> None:
         # Collect selected cluster IDs
@@ -438,7 +475,9 @@ class FaceSelectionScreen(Screen):
             if cluster.id == -1:
                 selected_ids.add(-1)
 
-        blur_method = self.query_one("#blur-method", Select).value
+        blur_method = str(self.query_one("#blur-method", Select).value)
+        if blur_method == "Select.NoSelection":
+            blur_method = "gaussian"
 
         # Generate output path
         stem = self.video_path.stem

src/faceblur/blur.py

@@ -145,13 +145,24 @@ def get_bboxes_for_frame(
     all_clusters = set(prev_by_cluster.keys()) | set(next_by_cluster.keys())
     for cid in all_clusters:
         if cid in prev_by_cluster and cid in next_by_cluster:
+            # Face present in both: standard linear interpolation
             bbox = interpolate_bboxes(prev_by_cluster[cid], next_by_cluster[cid], t)
             result.append((cid, bbox))
         elif cid in prev_by_cluster:
-            # Face leaving frame — use prev bbox (fade out handled by caller if desired)
-            result.append((cid, prev_by_cluster[cid]))
+            # Face leaving: shrink to center of previous bbox
+            x1, y1, x2, y2 = prev_by_cluster[cid]
+            cx, cy = (x1 + x2) // 2, (y1 + y2) // 2
+            center_bbox = (cx, cy, cx, cy)
+            # Interpolate from full bbox (t=0) to center point (t=1)
+            bbox = interpolate_bboxes(prev_by_cluster[cid], center_bbox, t)
+            result.append((cid, bbox))
         else:
-            # Face entering frame — use next bbox
-            result.append((cid, next_by_cluster[cid]))
+            # Face entering: grow from center of next bbox
+            x1, y1, x2, y2 = next_by_cluster[cid]
+            cx, cy = (x1 + x2) // 2, (y1 + y2) // 2
+            center_bbox = (cx, cy, cx, cy)
+            # Interpolate from center point (t=0) to full bbox (t=1)
+            bbox = interpolate_bboxes(center_bbox, next_by_cluster[cid], t)
+            result.append((cid, bbox))
 
     return result