feat(app): 创建图片选择+压缩处理器 — ImagePickerHandler

app/lib/features/editor/widgets/image_picker_handler.dart

@@ -0,0 +1,67 @@
+// 图片选择 + 压缩 + 缩略图生成工具类
+//
+// 职责：
+// - 从相机/相册选择图片
+// - 压缩到合理尺寸（≤1024px, 质量 85）
+// - 生成缩略图（≤200px, 质量 70）
+
+import 'package:flutter_image_compress/flutter_image_compress.dart';
+import 'package:image_picker/image_picker.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:uuid/uuid.dart';
+
+/// 图片选择 + 压缩 + 缩略图生成
+class ImagePickerHandler {
+  static const _uuid = Uuid();
+
+  /// 从相机或相册选择图片
+  /// 返回压缩后的本地文件路径，取消返回 null
+  static Future<String?> pickImage({required bool fromCamera}) async {
+    final picker = ImagePicker();
+    final xFile = await picker.pickImage(
+      source: fromCamera ? ImageSource.camera : ImageSource.gallery,
+      maxWidth: 1024,
+      maxHeight: 1024,
+      imageQuality: 85,
+    );
+    if (xFile == null) return null;
+
+    // 压缩图片
+    final compressedPath = await _compressImage(xFile.path);
+    return compressedPath;
+  }
+
+  /// 生成缩略图路径
+  static Future<String> generateThumbnail(String imagePath) async {
+    final dir = await getApplicationDocumentsDirectory();
+    final thumbName = 'thumb_${_uuid.v4()}.jpg';
+    final thumbPath = '${dir.path}/$thumbName';
+
+    final result = await FlutterImageCompress.compressAndGetFile(
+      imagePath,
+      thumbPath,
+      minHeight: 200,
+      minWidth: 200,
+      quality: 70,
+    );
+
+    return result?.path ?? imagePath;
+  }
+
+  /// 压缩原图
+  static Future<String> _compressImage(String path) async {
+    final dir = await getApplicationDocumentsDirectory();
+    final fileName = 'img_${_uuid.v4()}.jpg';
+    final targetPath = '${dir.path}/$fileName';
+
+    final result = await FlutterImageCompress.compressAndGetFile(
+      path,
+      targetPath,
+      quality: 85,
+      minWidth: 1024,
+      minHeight: 1024,
+    );
+
+    return result?.path ?? path;
+  }
+}