[mob] Handle error and empty face in visibility detector

mobile/lib/face/model/detection.dart

@@ -1,3 +1,4 @@
+import "package:logging/logging.dart";
 import "package:photos/face/model/box.dart";
 import "package:photos/face/model/landmark.dart";
 
@@ -49,35 +50,43 @@ class Detection {
 
   // TODO: iterate on better scoring logic, current is a placeholder
   int getVisibilityScore() {
-    final double aspectRatio = box.width / box.height;
-    final double eyeDistance = (landmarks[1].x - landmarks[0].x).abs();
-    final double mouthDistance = (landmarks[4].x - landmarks[3].x).abs();
-    final double noseEyeDistance =
-        (landmarks[2].y - ((landmarks[0].y + landmarks[1].y) / 2)).abs();
+    try {
+      if (isEmpty) {
+        return -1;
+      }
+      final double aspectRatio = box.width / box.height;
+      final double eyeDistance = (landmarks[1].x - landmarks[0].x).abs();
+      final double mouthDistance = (landmarks[4].x - landmarks[3].x).abs();
+      final double noseEyeDistance =
+          (landmarks[2].y - ((landmarks[0].y + landmarks[1].y) / 2)).abs();
 
-    final double normalizedEyeDistance = eyeDistance / box.width;
-    final double normalizedMouthDistance = mouthDistance / box.width;
-    final double normalizedNoseEyeDistance = noseEyeDistance / box.height;
+      final double normalizedEyeDistance = eyeDistance / box.width;
+      final double normalizedMouthDistance = mouthDistance / box.width;
+      final double normalizedNoseEyeDistance = noseEyeDistance / box.height;
 
-    const double aspectRatioThreshold = 0.8;
-    const double eyeDistanceThreshold = 0.2;
-    const double mouthDistanceThreshold = 0.3;
-    const double noseEyeDistanceThreshold = 0.1;
+      const double aspectRatioThreshold = 0.8;
+      const double eyeDistanceThreshold = 0.2;
+      const double mouthDistanceThreshold = 0.3;
+      const double noseEyeDistanceThreshold = 0.1;
 
-    double score = 0;
-    if (aspectRatio >= aspectRatioThreshold) {
-      score += 50;
-    }
-    if (normalizedEyeDistance >= eyeDistanceThreshold) {
-      score += 20;
-    }
-    if (normalizedMouthDistance >= mouthDistanceThreshold) {
-      score += 20;
-    }
-    if (normalizedNoseEyeDistance >= noseEyeDistanceThreshold) {
-      score += 10;
-    }
+      double score = 0;
+      if (aspectRatio >= aspectRatioThreshold) {
+        score += 50;
+      }
+      if (normalizedEyeDistance >= eyeDistanceThreshold) {
+        score += 20;
+      }
+      if (normalizedMouthDistance >= mouthDistanceThreshold) {
+        score += 20;
+      }
+      if (normalizedNoseEyeDistance >= noseEyeDistanceThreshold) {
+        score += 10;
+      }
 
-    return score.clamp(0, 100).toInt();
+      return score.clamp(0, 100).toInt();
+    } catch (e) {
+      Logger("FaceDetection").warning('Error calculating visibility score:', e);
+      return -1;
+    }
   }
 }