474 lines
13 KiB
Dart
474 lines
13 KiB
Dart
import 'dart:io';
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import 'package:flutter_image_compress/flutter_image_compress.dart';
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import 'package:image/image.dart' as img;
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import 'package:path/path.dart' as path;
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import 'package:uuid/uuid.dart';
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import '../constants/app_constants.dart';
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import '../errors/app_error.dart';
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import 'logger.dart';
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/// 图片处理工具类
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/// 提供图片压缩、格式转换、缩略图生成等功能
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class ImageUtils {
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// 私有构造函数，防止实例化
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ImageUtils._();
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static const Uuid _uuid = Uuid();
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/// 生成缩略图
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/// [imagePath] 原图路径
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/// [targetPath] 缩略图保存路径
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/// [maxSize] 缩略图最大尺寸（长边）
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/// [quality] 压缩质量（0-100）
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static Future<String> generateThumbnail({
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required String imagePath,
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required String targetPath,
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int maxSize = AppConstants.maxThumbnailSize,
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int quality = AppConstants.thumbnailQuality,
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}) async {
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try {
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Logger.debug('开始生成缩略图: $imagePath');
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// 检查原文件是否存在
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final originalFile = File(imagePath);
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if (!await originalFile.exists()) {
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throw ImageProcessingError(
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message: '原图文件不存在: $imagePath',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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// 获取文件信息
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final fileSize = await originalFile.length();
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Logger.debug('原图文件大小: ${fileSize / 1024 / 1024}MB');
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// 检查文件大小限制
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if (fileSize > AppConstants.maxImageSize) {
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throw ImageProcessingError(
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message: '图片文件过大，最大支持30MB',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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// 根据文件类型选择处理方式
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final fileExtension = path.extension(imagePath).toLowerCase();
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if (fileExtension == '.gif') {
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return await _generateGifThumbnail(
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imagePath: imagePath,
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targetPath: targetPath,
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maxSize: maxSize,
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quality: quality,
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);
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} else {
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return await _generateStaticImageThumbnail(
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imagePath: imagePath,
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targetPath: targetPath,
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maxSize: maxSize,
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quality: quality,
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);
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}
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} catch (error, stackTrace) {
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Logger.error('生成缩略图失败', error: error, stackTrace: stackTrace);
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if (error is ImageProcessingError) {
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rethrow;
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}
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throw ImageProcessingError(
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message: '生成缩略图失败: ${error.toString()}',
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code: 'IMAGE_PROCESSING_ERROR',
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stackTrace: stackTrace,
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);
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}
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}
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/// 生成静态图片缩略图
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static Future<String> _generateStaticImageThumbnail({
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required String imagePath,
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required String targetPath,
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required int maxSize,
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required int quality,
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}) async {
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try {
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// 使用 flutter_image_compress 进行压缩
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final result = await FlutterImageCompress.compressAndGetFile(
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imagePath,
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targetPath,
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quality: quality,
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minWidth: maxSize,
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minHeight: maxSize,
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format: CompressFormat.webp,
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keepExif: false,
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);
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if (result == null) {
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throw ImageProcessingError(
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message: '图片压缩失败，返回结果为空',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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Logger.debug('静态图片缩略图生成成功: ${result.path}');
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return result.path;
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} catch (error, stackTrace) {
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Logger.error('静态图片压缩失败', error: error, stackTrace: stackTrace);
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// 如果 flutter_image_compress 失败，使用 image 库作为备选方案
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return await _generateThumbnailWithImageLib(
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imagePath: imagePath,
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targetPath: targetPath,
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maxSize: maxSize,
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quality: quality,
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);
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}
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}
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/// 使用 image 库生成缩略图（备选方案）
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static Future<String> _generateThumbnailWithImageLib({
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required String imagePath,
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required String targetPath,
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required int maxSize,
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required int quality,
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}) async {
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try {
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// 读取原图
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final originalImage = img.decodeImage(await File(imagePath).readAsBytes());
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if (originalImage == null) {
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throw ImageProcessingError(
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message: '无法解码图片文件',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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// 计算缩放比例
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final originalWidth = originalImage.width;
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final originalHeight = originalImage.height;
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double scale = 1.0;
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if (originalWidth > originalHeight) {
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// 横图，以宽度为基准
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if (originalWidth > maxSize) {
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scale = maxSize / originalWidth;
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}
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} else {
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// 竖图或方图，以高度为基准
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if (originalHeight > maxSize) {
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scale = maxSize / originalHeight;
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}
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}
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final targetWidth = (originalWidth * scale).round();
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final targetHeight = (originalHeight * scale).round();
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Logger.debug('图片缩放: ${originalWidth}x$originalHeight -> ${targetWidth}x$targetHeight');
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// 缩放图片
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final resizedImage = img.copyResize(
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originalImage,
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width: targetWidth,
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height: targetHeight,
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);
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// 保存为JPEG格式（简化处理）
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final jpegData = img.encodeJpg(resizedImage, quality: quality);
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final thumbnailFile = File(targetPath);
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await thumbnailFile.writeAsBytes(jpegData);
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Logger.debug('使用 image 库生成缩略图成功: $targetPath');
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return targetPath;
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} catch (error, stackTrace) {
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throw ImageProcessingError(
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message: '图片库处理失败: ${error.toString()}',
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code: 'IMAGE_PROCESSING_ERROR',
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stackTrace: stackTrace,
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);
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}
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}
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/// 生成GIF缩略图
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static Future<String> _generateGifThumbnail({
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required String imagePath,
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required String targetPath,
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required int maxSize,
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required int quality,
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}) async {
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try {
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Logger.debug('处理GIF缩略图: $imagePath');
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// 读取GIF文件
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final gifFile = File(imagePath);
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final gifBytes = await gifFile.readAsBytes();
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// 解码GIF
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final gifImage = img.decodeGif(gifBytes);
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if (gifImage == null) {
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throw ImageProcessingError(
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message: '无法解码GIF文件',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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// 对于大GIF文件，只提取第一帧作为缩略图
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if (gifImage.length > 1) {
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Logger.debug('GIF文件包含 ${gifImage.length} 帧，提取第一帧作为缩略图');
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}
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// 获取第一帧
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final firstFrame = gifImage.frames.isNotEmpty ? gifImage.frames.first : null;
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if (firstFrame == null) {
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throw ImageProcessingError(
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message: '无法获取GIF的第一帧',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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// 计算缩放比例
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final originalWidth = firstFrame.width;
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final originalHeight = firstFrame.height;
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double scale = 1.0;
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if (originalWidth > originalHeight) {
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if (originalWidth > maxSize) {
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scale = maxSize / originalWidth;
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}
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} else {
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if (originalHeight > maxSize) {
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scale = maxSize / originalHeight;
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}
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}
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final targetWidth = (originalWidth * scale).round();
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final targetHeight = (originalHeight * scale).round();
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// 缩放第一帧
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final resizedFrame = img.copyResize(
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firstFrame,
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width: targetWidth,
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height: targetHeight,
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);
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// 保存为JPEG格式
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final jpegData = img.encodeJpg(resizedFrame, quality: quality);
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final thumbnailFile = File(targetPath);
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await thumbnailFile.writeAsBytes(jpegData);
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Logger.debug('GIF缩略图生成成功: $targetPath');
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return targetPath;
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} catch (error, stackTrace) {
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throw ImageProcessingError(
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message: 'GIF缩略图生成失败: ${error.toString()}',
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code: 'IMAGE_PROCESSING_ERROR',
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stackTrace: stackTrace,
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);
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}
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}
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/// 生成图片的唯一文件名
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/// [extension] 文件扩展名（包含点号）
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static String generateUniqueFileName(String extension) {
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final timestamp = DateTime.now().millisecondsSinceEpoch;
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final uuid = _uuid.v4().substring(0, 8);
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return '${timestamp}_$uuid$extension';
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}
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/// 根据MIME类型获取文件扩展名
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static String getExtensionFromMimeType(String mimeType) {
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final mimeTypeMap = {
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'image/jpeg': '.jpg',
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'image/jpg': '.jpg',
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'image/png': '.png',
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'image/gif': '.gif',
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'image/webp': '.webp',
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'image/heic': '.heic',
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'image/heif': '.heif',
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};
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return mimeTypeMap[mimeType.toLowerCase()] ?? '.jpg';
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}
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/// 获取图片的基本信息
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static Future<Map<String, dynamic>> getImageInfo(String imagePath) async {
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try {
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final file = File(imagePath);
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if (!await file.exists()) {
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throw ImageProcessingError(
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message: '图片文件不存在: $imagePath',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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final bytes = await file.readAsBytes();
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final image = img.decodeImage(bytes);
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if (image == null) {
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throw ImageProcessingError(
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message: '无法解码图片文件',
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code: 'IMAGE_PROCESSING_ERROR',
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);
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}
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return {
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'width': image.width,
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'height': image.height,
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'size': bytes.length,
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'format': path.extension(imagePath).toLowerCase(),
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'mimeType': _getMimeType(imagePath),
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};
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} catch (error, stackTrace) {
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Logger.error('获取图片信息失败', error: error, stackTrace: stackTrace);
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if (error is ImageProcessingError) {
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rethrow;
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}
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throw ImageProcessingError(
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message: '获取图片信息失败: ${error.toString()}',
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code: 'IMAGE_PROCESSING_ERROR',
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stackTrace: stackTrace,
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);
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}
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}
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/// 根据文件路径获取MIME类型
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static String _getMimeType(String filePath) {
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final extension = path.extension(filePath).toLowerCase();
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final mimeTypeMap = {
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'.jpg': 'image/jpeg',
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'.jpeg': 'image/jpeg',
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'.png': 'image/png',
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'.gif': 'image/gif',
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'.webp': 'image/webp',
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'.heic': 'image/heic',
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'.heif': 'image/heif',
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};
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return mimeTypeMap[extension] ?? 'image/jpeg';
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}
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/// 检查图片文件是否有效
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static Future<bool> isValidImage(String imagePath) async {
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try {
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final file = File(imagePath);
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if (!await file.exists()) {
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return false;
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}
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final fileSize = await file.length();
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if (fileSize == 0 || fileSize > AppConstants.maxImageSize) {
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return false;
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}
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final extension = path.extension(imagePath).toLowerCase();
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const validExtensions = ['.jpg', '.jpeg', '.png', '.gif', '.webp', '.heic', '.heif'];
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if (!validExtensions.contains(extension)) {
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return false;
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}
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// 尝试解码图片
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final bytes = await file.readAsBytes();
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final image = img.decodeImage(bytes);
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return image != null;
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} catch (error) {
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Logger.error('图片验证失败', error: error);
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return false;
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}
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}
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/// 计算图片的宽高比
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static double calculateAspectRatio(int width, int height) {
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if (width <= 0 || height <= 0) {
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return 1.0;
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}
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return width / height;
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}
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/// 根据目标宽度计算等比例高度
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static int calculateHeightForWidth(int originalWidth, int originalHeight, int targetWidth) {
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if (originalWidth <= 0) {
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return originalHeight;
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}
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return (originalHeight * targetWidth / originalWidth).round();
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}
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/// 根据目标高度计算等比例宽度
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static int calculateWidthForHeight(int originalWidth, int originalHeight, int targetHeight) {
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if (originalHeight <= 0) {
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return originalWidth;
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}
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return (originalWidth * targetHeight / originalHeight).round();
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}
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}
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/// 图片处理结果
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class ImageProcessingResult {
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final String originalPath;
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final String thumbnailPath;
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final Map<String, dynamic> metadata;
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final bool success;
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final String? errorMessage;
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ImageProcessingResult({
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required this.originalPath,
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required this.thumbnailPath,
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required this.metadata,
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this.success = true,
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this.errorMessage,
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});
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factory ImageProcessingResult.error(String originalPath, String errorMessage) {
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return ImageProcessingResult(
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originalPath: originalPath,
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thumbnailPath: '',
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metadata: {},
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success: false,
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errorMessage: errorMessage,
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);
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}
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}
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/// 支持的图片格式
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class SupportedImageFormats {
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static const List<String> formats = [
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'jpg',
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'jpeg',
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'png',
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'gif',
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'webp',
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'heic',
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'heif',
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];
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static const List<String> extensions = [
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'.jpg',
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'.jpeg',
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'.png',
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'.gif',
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'.webp',
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'.heic',
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'.heif',
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];
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/// 检查文件扩展名是否支持
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static bool isSupported(String filePath) {
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final extension = path.extension(filePath).toLowerCase();
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return extensions.contains(extension);
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}
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/// 检查MIME类型是否支持
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static bool isMimeTypeSupported(String mimeType) {
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final supportedMimeTypes = [
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'image/jpeg',
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'image/jpg',
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'image/png',
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'image/gif',
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'image/webp',
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'image/heic',
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'image/heif',
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];
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return supportedMimeTypes.contains(mimeType.toLowerCase());
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}
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} |