🚀 Allow the foreground builder to be used all the time (#97)

Author: AlexV525

CHANGELOG.md

@@ -4,6 +4,14 @@ that can be found in the LICENSE file. -->
 
 # Changelog
 
+## 3.2.1
+
+### Improvements
+
+- Allow the foreground builder to be used all the time (#97) .
+  The signature of the `ForegroundBuilder` has changed
+  but can be easily migrated.
+
 ## 3.2.0+1
 
 ### New features

lib/src/constants/type_defs.dart

@@ -43,10 +43,13 @@ typedef CameraErrorHandler = void Function(
 /// {@template wechat_camera_picker.ForegroundBuilder}
 /// Build the foreground/overlay widget with the given [CameraValue].
 /// 根据给定的 [CameraValue] 构建自定义的前景 widget
+///
+/// The [cameraValue] will be null until the [CameraController] initialized.
+/// 在 [CameraController] 完成初始化前，[cameraValue] 将为空。
 /// {@endtemplate}
 typedef ForegroundBuilder = Widget Function(
   BuildContext context,
-  CameraValue cameraValue,
+  CameraValue? cameraValue,
 );
 
 /// {@template wechat_camera_picker.PreviewTransformBuilder}

lib/src/widgets/camera_picker.dart

@@ -18,6 +18,7 @@ import '../constants/config.dart';
 import '../constants/constants.dart';
 import '../constants/enums.dart';
 import '../constants/styles.dart';
+import '../constants/type_defs.dart';
 import '../delegates/camera_picker_text_delegate.dart';
 import '../internals/extensions.dart';
 import '../internals/methods.dart';
@@ -1323,18 +1324,10 @@ class CameraPickerState extends State<CameraPicker>
     required BoxConstraints constraints,
   }) {
     return RepaintBoundary(
-      child: Stack(
-        children: <Widget>[
-          Positioned.fill(
-            child: _cameraPreview(
-              context,
-              orientation: value.deviceOrientation,
-              constraints: constraints,
-            ),
-          ),
-          if (config.foregroundBuilder != null)
-            Positioned.fill(child: config.foregroundBuilder!(context, value)),
-        ],
+      child: _cameraPreview(
+        context,
+        orientation: value.deviceOrientation,
+        constraints: constraints,
       ),
     );
   }
@@ -1363,6 +1356,17 @@ class CameraPickerState extends State<CameraPicker>
     );
   }
 
+  Widget _foregroundBuilder(BuildContext context) {
+    final ForegroundBuilder builder = config.foregroundBuilder!;
+    if (_controller == null) {
+      return builder(context, null);
+    }
+    return ValueListenableBuilder<CameraValue>(
+      valueListenable: _controller!,
+      builder: (BuildContext c, CameraValue v, __) => builder(c, v),
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     return AnnotatedRegion<SystemUiOverlayStyle>(
@@ -1393,6 +1397,8 @@ class CameraPickerState extends State<CameraPicker>
                     builder: (_, __) => _focusingAreaWidget(constraints),
                   ),
                   _contentBuilder(constraints),
+                  if (config.foregroundBuilder != null)
+                    Positioned.fill(child: _foregroundBuilder(context)),
                 ],
               ),
             ),

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: 3.2.0+1
+version: 3.2.1
 homepage: https://github.com/fluttercandies/flutter_wechat_camera_picker
 
 environment: