Proposed solution to #154 [BUG] iOS front camera flash can be set ... (#156)

This is a proposed solution to #154 [BUG] iOS front camera flash can be
set from auto to on but not further .

This solves the unsupported flash modes exception by falling back on the
next mode with an infinite loop prevention control (just in case no
flash mode is supported).

Co-authored-by: Alex Li <[email protected]>

Author: lcuis

CHANGELOG.md

@@ -4,6 +4,12 @@ that can be found in the LICENSE file. -->
 
 # Changelog
 
+## 3.7.0
+
+### Improvements
+
+- Allow flash modes failed to switch and can move on to next when switching. (#156)
+
 ## 3.6.5
 
 ### Fixes

example/pubspec.yaml

@@ -1,6 +1,6 @@
 name: wechat_camera_picker_demo
 description: A new Flutter project.
-version: 3.6.5+21
+version: 3.7.0+22
 publish_to: none
 
 environment:

lib/src/states/camera_picker_state.dart

@@ -114,6 +114,13 @@ class CameraPickerState extends State<CameraPicker>
   /// 但如果录像时间没有限制，定时器将不会起作用。
   Timer? recordCountdownTimer;
 
+  /// Initialized with all the flash modes for each camera. If a flash mode is
+  /// not valid, it is removed from the list.
+  /// 使用每个相机的所有闪光灯模式进行初始化。
+  /// 如果闪光灯模式无效，则将其从列表中删除。
+  final Map<CameraDescription, List<FlashMode>> validFlashModes =
+      <CameraDescription, List<FlashMode>>{};
+
   ////////////////////////////////////////////////////////////////////////////
   ////////////////////////////// Global Getters //////////////////////////////
   ////////////////////////////////////////////////////////////////////////////
@@ -272,6 +279,7 @@ class CameraPickerState extends State<CameraPicker>
         );
       }
 
+      initFlashModesForCameras();
       final int preferredIndex = cameras.indexWhere(
         (CameraDescription e) =>
             e.lensDirection == pickerConfig.preferredLensDirection,
@@ -343,6 +351,24 @@ class CameraPickerState extends State<CameraPicker>
     });
   }
 
+  /// Initializes the flash modes in [validFlashModes] for each
+  /// [CameraDescription].
+  /// 为每个 [CameraDescription] 在 [validFlashModes] 中初始化闪光灯模式。
+  void initFlashModesForCameras() {
+    for (final CameraDescription camera in cameras) {
+      if (!validFlashModes.containsKey(camera)) {
+        // Mind the order of this list as it has an impact on the switch cycle.
+        // Do not use FlashMode.values.
+        validFlashModes[camera] = <FlashMode>[
+          FlashMode.auto,
+          FlashMode.always,
+          FlashMode.torch,
+          FlashMode.off,
+        ];
+      }
+    }
+  }
+
   /// Switch cameras in order. When the [currentCameraIndex] reached the length
   /// of cameras, start from the beginning.
   /// 按顺序切换相机。当达到相机数量时从头开始。
@@ -369,25 +395,33 @@ class CameraPickerState extends State<CameraPicker>
 
   /// The method to switch between flash modes.
   /// 切换闪光灯模式的方法
-  Future<void> switchFlashesMode() async {
-    final FlashMode newFlashMode;
-    switch (controller.value.flashMode) {
-      case FlashMode.off:
-        newFlashMode = FlashMode.auto;
-        break;
-      case FlashMode.auto:
-        newFlashMode = FlashMode.always;
-        break;
-      case FlashMode.always:
-        newFlashMode = FlashMode.torch;
-        break;
-      case FlashMode.torch:
-        newFlashMode = FlashMode.off;
-        break;
+  Future<void> switchFlashesMode(CameraValue value) async {
+    final List<FlashMode> flashModes = validFlashModes[currentCamera]!;
+    if (flashModes.isEmpty) {
+      // Unlikely event that no flash mode is valid for current camera.
+      handleErrorWithHandler(
+        CameraException(
+          'No FlashMode found.',
+          'No flash modes are available with the camera.',
+        ),
+        pickerConfig.onError,
+      );
+      return;
+    }
+    final int currentFlashModeIndex = flashModes.indexOf(value.flashMode);
+    final int nextFlashModeIndex;
+    if (currentFlashModeIndex + 1 >= flashModes.length) {
+      nextFlashModeIndex = 0;
+    } else {
+      nextFlashModeIndex = currentFlashModeIndex + 1;
     }
+    final FlashMode nextFlashMode = flashModes[nextFlashModeIndex];
     try {
-      await controller.setFlashMode(newFlashMode);
+      await controller.setFlashMode(nextFlashMode);
     } catch (e, s) {
+      // Remove the flash mode that throws an exception.
+      validFlashModes[currentCamera]!.remove(nextFlashMode);
+      switchFlashesMode(value);
       handleErrorWithHandler(e, pickerConfig.onError, s: s);
     }
   }
@@ -863,7 +897,7 @@ class CameraPickerState extends State<CameraPicker>
         break;
     }
     return IconButton(
-      onPressed: switchFlashesMode,
+      onPressed: () => switchFlashesMode(value),
       tooltip: textDelegate.sFlashModeLabel(value.flashMode),
       icon: Icon(icon, size: 24),
     );

pubspec.yaml

@@ -1,7 +1,7 @@
 name: wechat_camera_picker
 description: A camera picker based on WeChat's UI which is a separate runnable extension to wechat_assets_picker.
 repository: https://github.com/fluttercandies/flutter_wechat_camera_picker
-version: 3.6.5
+version: 3.7.0
 
 environment:
   sdk: ">=2.14.0 <3.0.0"