⚡️ Improve tapping exposure updates (#109)

Author: AlexV525

CHANGELOG.md

@@ -4,14 +4,15 @@ that can be found in the LICENSE file. -->
 
 # Changelog
 
-## 3.3.1
+## 3.4.0
 
 ### New features
 
 - Add `enableScaledPreview`. (#108)
 
 ### Improvements
 
+- Improve tapping exposure updates. (#109)
 - Prevent unnecessary zoom updates. (#107)
 
 ## 3.3.0

example/pubspec.yaml

@@ -1,6 +1,6 @@
 name: wechat_camera_picker_demo
 description: A new Flutter project.
-version: 3.3.1+12
+version: 3.4.0+13
 publish_to: none
 
 environment:

lib/src/widgets/camera_picker.dart

@@ -9,6 +9,7 @@ import 'dart:math' as math;
 
 import 'package:bindings_compatible/bindings_compatible.dart';
 import 'package:camera/camera.dart';
+import 'package:camera_platform_interface/camera_platform_interface.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/semantics.dart';
@@ -154,13 +155,9 @@ class CameraPickerState extends State<CameraPicker>
   /// 当前曝光值
   final ValueNotifier<double> _currentExposureOffset = ValueNotifier<double>(0);
 
-  /// The maximum available value for exposure.
-  /// 最大可用曝光值
   double _maxAvailableExposureOffset = 0;
-
-  /// The minimum available value for exposure.
-  /// 最小可用曝光值
   double _minAvailableExposureOffset = 0;
+  double _exposureStep = 0;
 
   /// The maximum available value for zooming.
   /// 最大可用缩放值
@@ -426,10 +423,13 @@ class CameraPickerState extends State<CameraPicker>
               newController
                   .lockCaptureOrientation(config.lockCaptureOrientation),
             newController
-                .getMinExposureOffset()
-                .then((double value) => _maxAvailableExposureOffset = value),
+                .getExposureOffsetStepSize()
+                .then((double value) => _exposureStep = value),
             newController
                 .getMaxExposureOffset()
+                .then((double value) => _maxAvailableExposureOffset = value),
+            newController
+                .getMinExposureOffset()
                 .then((double value) => _minAvailableExposureOffset = value),
             newController
                 .getMaxZoomLevel()
@@ -603,12 +603,33 @@ class CameraPickerState extends State<CameraPicker>
 
   /// Update the exposure offset using the exposure controller.
   /// 使用曝光控制器更新曝光值
-  void updateExposureOffset(double value) {
-    if (value == _currentExposureOffset.value) {
+  Future<void> updateExposureOffset(double value) async {
+    // Normalize the new exposure value if exposures have steps.
+    if (_exposureStep > 0) {
+      final double inv = 1.0 / _exposureStep;
+      double roundedOffset = (value * inv).roundToDouble() / inv;
+      if (roundedOffset > _maxAvailableExposureOffset) {
+        roundedOffset = (value * inv).floorToDouble() / inv;
+      } else if (roundedOffset < _minAvailableExposureOffset) {
+        roundedOffset = (value * inv).ceilToDouble() / inv;
+      }
+      value = roundedOffset;
+    }
+    if (value == _currentExposureOffset.value ||
+        value < _minAvailableExposureOffset ||
+        value > _maxAvailableExposureOffset) {
       return;
     }
     _currentExposureOffset.value = value;
-    controller.setExposureOffset(value);
+    try {
+      // Use [CameraPlatform] explicitly to reduce channel calls.
+      await CameraPlatform.instance.setExposureOffset(
+        controller.cameraId,
+        value,
+      );
+    } catch (e, s) {
+      handleErrorWithHandler(e, config.onError, s: s);
+    }
     if (!_isExposureModeDisplays.value) {
       _isExposureModeDisplays.value = true;
     }

pubspec.yaml

@@ -1,6 +1,6 @@
 name: wechat_camera_picker
 description: A camera picker which is an extension to wechat_assets_picker, but can be run separately.
-version: 3.3.1
+version: 3.4.0
 homepage: https://github.com/fluttercandies/flutter_wechat_camera_picker
 
 environment:
@@ -13,6 +13,7 @@ dependencies:
 
   bindings_compatible: ^1.0.1
   camera: ^0.9.6
+  camera_platform_interface: ^2.1.5
   path: ^1.8.0
   path_provider: ^2.0.8
   photo_manager: ^2.1.0+2