保存图片/视频到相册的指令，增加对base64编码的图片处理

lib/data/repositories/message/save_to_album_handler.dart

+import 'dart:convert';
+import 'dart:io';
 import 'package:appframe/services/dispatcher.dart';
 import 'package:gallery_saver_plus/gallery_saver.dart';
+import 'package:path_provider/path_provider.dart';
 
 class SaveToAlbumHandler extends MessageHandler {
   @override
@@ -13,23 +16,21 @@ class SaveToAlbumHandler extends MessageHandler {
       return false;
     }
 
-    bool isVideo =
-        filePath.endsWith('.mp4') ||
-        filePath.endsWith('.avi') ||
-        filePath.endsWith('.mov') ||
-        filePath.endsWith('.mkv') ||
-        filePath.endsWith('.wmv') ||
-        filePath.endsWith('.flv') ||
-        filePath.endsWith('.webm') ||
-        filePath.endsWith('.m4v') ||
-        filePath.endsWith('.3gp');
+    String actualFilePath;
+    if (_isBase64(filePath)) {
+      actualFilePath = await _saveBase64ToFile(filePath);
+    } else {
+      actualFilePath = filePath;
+    }
+
+    bool isVideo = _isVideoFile(actualFilePath);
 
     try {
       if (isVideo) {
-        final bool? success = await GallerySaver.saveVideo(filePath);
+        final bool? success = await GallerySaver.saveVideo(actualFilePath);
         return success ?? false;
       } else {
-        final bool? success = await GallerySaver.saveImage(filePath);
+        final bool? success = await GallerySaver.saveImage(actualFilePath);
         return success ?? false;
       }
     } catch (e) {
@@ -37,4 +38,49 @@ class SaveToAlbumHandler extends MessageHandler {
       return false;
     }
   }
+
+  bool _isBase64(String str) {
+    if (str.startsWith('data:image/')) {
+      return true;
+    }
+    try {
+      base64Decode(str);
+      return true;
+    } catch (e) {
+      return false;
+    }
+  }
+
+  Future<String> _saveBase64ToFile(String base64Str) async {
+    String base64Data = base64Str;
+    String fileExtension = 'png';
+
+    if (base64Str.startsWith('data:image/')) {
+      final regExp = RegExp(r'data:image/(\w+);base64,(.+)');
+      final match = regExp.firstMatch(base64Str);
+      if (match != null) {
+        fileExtension = match.group(1) ?? 'png';
+        base64Data = match.group(2) ?? '';
+      }
+    }
+
+    final bytes = base64Decode(base64Data);
+    final tempDir = await getTemporaryDirectory();
+    final filePath = '${tempDir.path}/${DateTime.now().millisecondsSinceEpoch}.$fileExtension';
+    final file = File(filePath);
+    await file.writeAsBytes(bytes);
+    return filePath;
+  }
+
+  bool _isVideoFile(String filePath) {
+    return filePath.endsWith('.mp4') ||
+        filePath.endsWith('.avi') ||
+        filePath.endsWith('.mov') ||
+        filePath.endsWith('.mkv') ||
+        filePath.endsWith('.wmv') ||
+        filePath.endsWith('.flv') ||
+        filePath.endsWith('.webm') ||
+        filePath.endsWith('.m4v') ||
+        filePath.endsWith('.3gp');
+  }
 }