[camera] Fix initialization error in camera example on iOS (flutter#3406)

BeMacized · mvanbeusekom · web-flow · commit d0b7109f6b00 · 2021-01-14T10:33:03.000+01:00
* Fix error on first camera initialize in example app

* Improved error handling a bit &amp; updated tests.

* Updated pubspec and changelog

Co-authored-by: Maurits van Beusekom &lt;maurits@baseflow.com&gt;
diff --git a/packages/camera/camera/CHANGELOG.md b/packages/camera/camera/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.7.0+2
+
+* Improved error feedback by differentiating between uninitialized and disposed camera controllers.
+
 ## 0.7.0+1
 
 * Fixes picture captures causing a crash on some Huawei devices.
diff --git a/packages/camera/camera/example/lib/main.dart b/packages/camera/camera/example/lib/main.dart
@@ -580,10 +580,16 @@ class _CameraExampleHomeState extends State<CameraExampleHome>
 
     try {
       await controller.initialize();
-      _minAvailableExposureOffset = await controller.getMinExposureOffset();
-      _maxAvailableExposureOffset = await controller.getMaxExposureOffset();
-      _maxAvailableZoom = await controller.getMaxZoomLevel();
-      _minAvailableZoom = await controller.getMinZoomLevel();
+      await Future.wait([
+        controller
+            .getMinExposureOffset()
+            .then((value) => _minAvailableExposureOffset = value),
+        controller
+            .getMaxExposureOffset()
+            .then((value) => _maxAvailableExposureOffset = value),
+        controller.getMaxZoomLevel().then((value) => _maxAvailableZoom = value),
+        controller.getMinZoomLevel().then((value) => _minAvailableZoom = value),
+      ]);
     } on CameraException catch (e) {
       _showCameraException(e);
     }
diff --git a/packages/camera/camera/lib/src/camera_controller.dart b/packages/camera/camera/lib/src/camera_controller.dart
@@ -323,12 +323,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// Throws a [CameraException] if the capture fails.
   Future<XFile> takePicture() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController.',
-        'takePicture was called on uninitialized CameraController',
-      );
-    }
+    _throwIfNotInitialized("takePicture");
     if (value.isTakingPicture) {
       throw CameraException(
         'Previous capture has not returned yet.',
@@ -366,13 +361,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   Future<void> startImageStream(onLatestImageAvailable onAvailable) async {
     assert(defaultTargetPlatform == TargetPlatform.android ||
         defaultTargetPlatform == TargetPlatform.iOS);
-
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'startImageStream was called on uninitialized CameraController.',
-      );
-    }
+    _throwIfNotInitialized("startImageStream");
     if (value.isRecordingVideo) {
       throw CameraException(
         'A video recording is already started.',
@@ -412,13 +401,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   Future<void> stopImageStream() async {
     assert(defaultTargetPlatform == TargetPlatform.android ||
         defaultTargetPlatform == TargetPlatform.iOS);
-
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'stopImageStream was called on uninitialized CameraController.',
-      );
-    }
+    _throwIfNotInitialized("stopImageStream");
     if (value.isRecordingVideo) {
       throw CameraException(
         'A video recording is already started.',
@@ -448,12 +431,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   /// The video is returned as a [XFile] after calling [stopVideoRecording].
   /// Throws a [CameraException] if the capture fails.
   Future<void> startVideoRecording() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'startVideoRecording was called on uninitialized CameraController',
-      );
-    }
+    _throwIfNotInitialized("startVideoRecording");
     if (value.isRecordingVideo) {
       throw CameraException(
         'A video recording is already started.',
@@ -483,12 +461,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// Throws a [CameraException] if the capture failed.
   Future<XFile> stopVideoRecording() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'stopVideoRecording was called on uninitialized CameraController',
-      );
-    }
+    _throwIfNotInitialized("stopVideoRecording");
     if (!value.isRecordingVideo) {
       throw CameraException(
         'No video is recording',
@@ -511,12 +484,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// This feature is only available on iOS and Android sdk 24+.
   Future<void> pauseVideoRecording() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'pauseVideoRecording was called on uninitialized CameraController',
-      );
-    }
+    _throwIfNotInitialized("pauseVideoRecording");
     if (!value.isRecordingVideo) {
       throw CameraException(
         'No video is recording',
@@ -535,12 +503,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// This feature is only available on iOS and Android sdk 24+.
   Future<void> resumeVideoRecording() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'resumeVideoRecording was called on uninitialized CameraController',
-      );
-    }
+    _throwIfNotInitialized("resumeVideoRecording");
     if (!value.isRecordingVideo) {
       throw CameraException(
         'No video is recording',
@@ -557,12 +520,7 @@ class CameraController extends ValueNotifier<CameraValue> {
 
   /// Returns a widget showing a live camera preview.
   Widget buildPreview() {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'buildView() was called on uninitialized CameraController.',
-      );
-    }
+    _throwIfNotInitialized("buildPreview");
     try {
       return CameraPlatform.instance.buildPreview(_cameraId);
     } on PlatformException catch (e) {
@@ -572,13 +530,7 @@ class CameraController extends ValueNotifier<CameraValue> {
 
   /// Gets the maximum supported zoom level for the selected camera.
   Future<double> getMaxZoomLevel() {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'getMaxZoomLevel was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("getMaxZoomLevel");
     try {
       return CameraPlatform.instance.getMaxZoomLevel(_cameraId);
     } on PlatformException catch (e) {
@@ -588,13 +540,7 @@ class CameraController extends ValueNotifier<CameraValue> {
 
   /// Gets the minimum supported zoom level for the selected camera.
   Future<double> getMinZoomLevel() {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'getMinZoomLevel was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("getMinZoomLevel");
     try {
       return CameraPlatform.instance.getMinZoomLevel(_cameraId);
     } on PlatformException catch (e) {
@@ -608,13 +554,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   /// zoom level returned by the `getMaxZoomLevel`. Throws an `CameraException`
   /// when an illegal zoom level is suplied.
   Future<void> setZoomLevel(double zoom) {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'setZoomLevel was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("setZoomLevel");
     try {
       return CameraPlatform.instance.setZoomLevel(_cameraId, zoom);
     } on PlatformException catch (e) {
@@ -666,13 +606,7 @@ class CameraController extends ValueNotifier<CameraValue> {
 
   /// Gets the minimum supported exposure offset for the selected camera in EV units.
   Future<double> getMinExposureOffset() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'getMinExposureOffset was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("getMinExposureOffset");
     try {
       return CameraPlatform.instance.getMinExposureOffset(_cameraId);
     } on PlatformException catch (e) {
@@ -682,13 +616,7 @@ class CameraController extends ValueNotifier<CameraValue> {
 
   /// Gets the maximum supported exposure offset for the selected camera in EV units.
   Future<double> getMaxExposureOffset() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'getMaxExposureOffset was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("getMaxExposureOffset");
     try {
       return CameraPlatform.instance.getMaxExposureOffset(_cameraId);
     } on PlatformException catch (e) {
@@ -700,13 +628,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// Returns 0 when the camera supports using a free value without stepping.
   Future<double> getExposureOffsetStepSize() async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'getExposureOffsetStepSize was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("getExposureOffsetStepSize");
     try {
       return CameraPlatform.instance.getExposureOffsetStepSize(_cameraId);
     } on PlatformException catch (e) {
@@ -726,13 +648,7 @@ class CameraController extends ValueNotifier<CameraValue> {
   ///
   /// Returns the (rounded) offset value that was set.
   Future<double> setExposureOffset(double offset) async {
-    if (!value.isInitialized || _isDisposed) {
-      throw CameraException(
-        'Uninitialized CameraController',
-        'setExposureOffset was called on uninitialized CameraController',
-      );
-    }
-
+    _throwIfNotInitialized("setExposureOffset");
     // Check if offset is in range
     List<double> range =
         await Future.wait([getMinExposureOffset(), getMaxExposureOffset()]);
@@ -834,4 +750,19 @@ class CameraController extends ValueNotifier<CameraValue> {
       await CameraPlatform.instance.dispose(_cameraId);
     }
   }
+
+  void _throwIfNotInitialized(String functionName) {
+    if (!value.isInitialized) {
+      throw CameraException(
+        'Uninitialized CameraController',
+        '$functionName() was called on an uninitialized CameraController.',
+      );
+    }
+    if (_isDisposed) {
+      throw CameraException(
+        'Disposed CameraController',
+        '$functionName() was called on a disposed CameraController.',
+      );
+    }
+  }
 }
diff --git a/packages/camera/camera/pubspec.yaml b/packages/camera/camera/pubspec.yaml
@@ -2,7 +2,7 @@ name: camera
 description: A Flutter plugin for getting information about and controlling the
   camera on Android and iOS. Supports previewing the camera feed, capturing images, capturing video,
   and streaming image buffers to dart.
-version: 0.7.0+1
+version: 0.7.0+2
 homepage: https://github.com/flutter/plugins/tree/master/packages/camera/camera
 
 dependencies:
diff --git a/packages/camera/camera/test/camera_image_stream_test.dart b/packages/camera/camera/test/camera_image_stream_test.dart
@@ -22,12 +22,21 @@ void main() {
         ResolutionPreset.max);
 
     expect(
-        () => cameraController.startImageStream((image) => null),
-        throwsA(isA<CameraException>().having(
-          (error) => error.description,
-          'Uninitialized CameraController.',
-          'startImageStream was called on uninitialized CameraController.',
-        )));
+      () => cameraController.startImageStream((image) => null),
+      throwsA(
+        isA<CameraException>()
+            .having(
+              (error) => error.code,
+              'code',
+              'Uninitialized CameraController',
+            )
+            .having(
+              (error) => error.description,
+              'description',
+              'startImageStream() was called on an uninitialized CameraController.',
+            ),
+      ),
+    );
   });
 
   test('startImageStream() throws $CameraException when recording videos',
@@ -107,12 +116,21 @@ void main() {
         ResolutionPreset.max);
 
     expect(
-        cameraController.stopImageStream,
-        throwsA(isA<CameraException>().having(
-          (error) => error.description,
-          'Uninitialized CameraController.',
-          'stopImageStream was called on uninitialized CameraController.',
-        )));
+      cameraController.stopImageStream,
+      throwsA(
+        isA<CameraException>()
+            .having(
+              (error) => error.code,
+              'code',
+              'Uninitialized CameraController',
+            )
+            .having(
+              (error) => error.description,
+              'description',
+              'stopImageStream() was called on an uninitialized CameraController.',
+            ),
+      ),
+    );
   });
 
   test('stopImageStream() throws $CameraException when recording videos',
diff --git a/packages/camera/camera/test/camera_test.dart b/packages/camera/camera/test/camera_test.dart
