[camera_android_camerax] Fix setFocusMode(auto) crash when there is no auto-focus point

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.7.2+2
+
+* Fixes a `StateError` ("Bad state: No element") in `setFocusMode(FocusMode.auto)`
+  when the current focus and metering action has no auto-focus points.
+
 ## 0.7.2+1
 
 * Migrates to Built-in Kotlin to support AGP 9.

packages/camera/camera_android_camerax/lib/src/android_camera_camerax.dart

@@ -632,9 +632,12 @@ class AndroidCameraCameraX extends CameraPlatform {
       case FocusMode.auto:
         // Determine auto-focus point to restore, if any. We do not restore
         // default auto-focus point if set previously to lock focus.
-        final MeteringPoint? unLockedFocusPoint = _defaultFocusPointLocked
+        final List<MeteringPoint> possibleCurrentAfPoints =
+            currentFocusMeteringAction?.meteringPointsAf ?? [];
+        final MeteringPoint? unLockedFocusPoint =
+            _defaultFocusPointLocked || possibleCurrentAfPoints.isEmpty
             ? null
-            : currentFocusMeteringAction!.meteringPointsAf.first;
+            : possibleCurrentAfPoints.first;
         _defaultFocusPointLocked = false;
         autoFocusPoint = unLockedFocusPoint;
         disableAutoCancel = false;

packages/camera/camera_android_camerax/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_android_camerax
 description: Android implementation of the camera plugin using the CameraX library.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_android_camerax
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.7.2+1
+version: 0.7.2+2
 
 environment:
   sdk: ^3.12.0

packages/camera/camera_android_camerax/test/android_camera_camerax_test.dart

@@ -4967,6 +4967,44 @@ void main() {
     },
   );
 
+  test(
+    'setFocusMode does not throw when setting auto-focus mode and the current focus and metering action has no auto-focus point',
+    () async {
+      final camera = AndroidCameraCameraX();
+      const cameraId = 11;
+      final mockCameraControl = MockCameraControl();
+      final FocusMeteringResult mockFocusMeteringResult = MockFocusMeteringResult();
+      final mockCamera2CameraControl = MockCamera2CameraControl();
+      const point = Point<double>(0.1, 0.2);
+
+      // Set directly for test versus calling createCamera.
+      camera.cameraInfo = MockCameraInfo();
+      camera.cameraControl = mockCameraControl;
+
+      when(
+        mockCamera2CameraControl.addCaptureRequestOptions(any),
+      ).thenAnswer((_) async => Future.value());
+
+      setUpOverridesForSettingFocusandExposurePoints(mockCameraControl, mockCamera2CameraControl);
+
+      // Make setting focus and metering action successful for test.
+      when(mockFocusMeteringResult.isFocusSuccessful).thenReturn(true);
+      when(
+        mockCameraControl.startFocusAndMetering(any),
+      ).thenAnswer((_) async => Future.value(mockFocusMeteringResult));
+
+      // Lock focus while an auto-focus point exists, then clear it, leaving a
+      // non-null action whose auto-focus point list is empty.
+      await camera.setExposurePoint(cameraId, point);
+      await camera.setFocusPoint(cameraId, point);
+      await camera.setFocusMode(cameraId, FocusMode.locked);
+      await camera.setFocusPoint(cameraId, null);
+
+      // Switching back to auto-focus must not throw.
+      await expectLater(camera.setFocusMode(cameraId, FocusMode.auto), completes);
+    },
+  );
+
   test(
     'setFocusMode starts expected focus and metering action with previously set auto-focus point if setting locked focus mode and current focus and metering action has auto-focus point',
     () async {