feat(app): crop cover & banner before upload (crop_your_image, 16:9 / 3:1)

review fixes: drop GIF from pre-sniff (package maps gif→png decode → never-ready hang); PopScope blocks back during processing

Co-Authored-By: Claude Code <noreply@anthropic.com>
This commit is contained in:
浅念
2026-09-28 15:39:39 +08:00
parent 97db504e25
commit 683e19bdc1
10 changed files with 632 additions and 7 deletions
+31 -4
View File
@@ -31,6 +31,7 @@ import '../features/uploads/enqueue.dart';
import '../l10n/app_localizations.dart';
import '../ui/components/section_header.dart';
import '../ui/tokens.dart';
import 'image_crop_page.dart';
/// 创建([existing] 为 null)/ 编辑相册表单。
class AlbumFormPage extends ConsumerStatefulWidget {
@@ -497,17 +498,43 @@ class _AlbumFormPageState extends ConsumerState<AlbumFormPage>
],
);
/// 选图后必经裁剪:封面 16:9(表单预览区比例),输出宽 ≤1920。
Future<void> _pickCoverImage() async {
final path = await ref.read(singleImagePickerProvider)();
if (path != null) {
setState(() => _coverFilePath = path);
if (path == null || !mounted) {
return;
}
final cropped = await Navigator.of(context).push<String>(
MaterialPageRoute(
builder: (_) => ImageCropPage(
sourcePath: path,
aspectRatio: 16 / 9,
maxOutputWidth: 1920,
),
),
);
if (cropped != null && mounted) {
setState(() => _coverFilePath = cropped);
}
}
/// 选图后必经裁剪:宣传图 3:1(观众页横幅),输出宽 ≤2400。
Future<void> _pickBannerImage() async {
final path = await ref.read(singleImagePickerProvider)();
if (path != null) {
setState(() => _bannerFilePath = path);
if (path == null || !mounted) {
return;
}
final cropped = await Navigator.of(context).push<String>(
MaterialPageRoute(
builder: (_) => ImageCropPage(
sourcePath: path,
aspectRatio: 3 / 1,
maxOutputWidth: 2400,
),
),
);
if (cropped != null && mounted) {
setState(() => _bannerFilePath = cropped);
}
}
+307
View File
@@ -0,0 +1,307 @@
/// 封面/宣传图裁剪页:固定纵横比交互裁剪 → 等比缩放上限 → JPEG 落盘。
///
/// 输入 image_picker 选中的本机路径;输出裁剪后的临时文件路径
/// (`{tmp}/album_assets/crop_{ms}.jpg`);取消/失败返回 null。
/// 封面 16:9(输出宽 ≤1920)、宣传图 3:1(输出宽 ≤2400)由调用方给定。
///
/// crop_your_image 2.0.0 为回调式 API:`CropController.crop()` 是 void,
/// 裁剪结果经 `onCropped` 回调(`CropSuccess.croppedImage` /
/// `CropFailure.cause`)。像素级 decode/缩放/编码统一放
/// `Isolate.run`,避免大图卡死主 isolate。
library;
import 'dart:io';
import 'dart:isolate';
import 'dart:typed_data';
import 'package:crop_your_image/crop_your_image.dart';
import 'package:flutter/material.dart';
import 'package:image/image.dart' as img;
import '../l10n/app_localizations.dart';
import '../ui/tokens.dart';
/// 裁剪页输出目录(应用临时目录下的 album_assets;测试直接可用真实 FS)。
Directory _cropOutputDir() {
final dir = Directory(
'${Directory.systemTemp.path}${Platform.pathSeparator}album_assets',
);
dir.createSync(recursive: true);
return dir;
}
/// 裁剪字节 → 可解码格式预检(魔数嗅探;HEIC/GIF 等走不支持提示)。
///
/// 包内解析失败(`_parseImageWith` 的 compute 抛错)不会回调页面——
/// 页面在交给 [Crop] 前先嗅探,拦下注定解析失败的源。
/// GIF 明确不支持:包内 formatDetector 的兜底分支按 png 解码
/// (`_ => ImageFormat.png`),decodePng(gif) 必然失败 → onStatusChanged
/// 永不 ready → 页面挂死在加载态。
bool _hasSupportedSignature(Uint8List bytes) {
if (bytes.length < 12) {
return false;
}
final jpeg = bytes[0] == 0xFF && bytes[1] == 0xD8 && bytes[2] == 0xFF;
final png =
bytes[0] == 0x89 &&
bytes[1] == 0x50 &&
bytes[2] == 0x4E &&
bytes[3] == 0x47;
final bmp = bytes[0] == 0x42 && bytes[1] == 0x4D;
final webp =
bytes[0] == 0x52 &&
bytes[1] == 0x49 &&
bytes[2] == 0x46 &&
bytes[3] == 0x46 &&
bytes[8] == 0x57 &&
bytes[9] == 0x45 &&
bytes[10] == 0x42 &&
bytes[11] == 0x50;
return jpeg || png || bmp || webp;
}
/// 裁剪输出编码 + 落盘(只在 isolate 内执行)。
String _encodeCropToJpeg(Uint8List cropped, int? maxOutputWidth) {
final decoded = img.decodeImage(cropped);
if (decoded == null) {
throw img.ImageException('crop output is not decodable');
}
var output = decoded;
if (maxOutputWidth != null && decoded.width > maxOutputWidth) {
output = img.copyResize(decoded, width: maxOutputWidth);
}
final file = File(
'${_cropOutputDir().path}${Platform.pathSeparator}'
'crop_${DateTime.now().millisecondsSinceEpoch}.jpg',
);
file.writeAsBytesSync(img.encodeJpg(output, quality: 90));
return file.path;
}
/// 封面/宣传图裁剪页。
class ImageCropPage extends StatefulWidget {
const ImageCropPage({
super.key,
required this.sourcePath,
required this.aspectRatio,
this.maxOutputWidth,
});
/// 源图本机路径(image_picker 单选返回)。
final String sourcePath;
/// 目标宽高比(宽/高):封面 16/9、宣传图 3/1。
final double aspectRatio;
/// 输出宽度上限(等比缩放;null=保持裁剪原分辨率)。
final int? maxOutputWidth;
@override
State<ImageCropPage> createState() => _ImageCropPageState();
}
class _ImageCropPageState extends State<ImageCropPage> {
final CropController _controller = CropController();
late final Future<Uint8List> _sourceBytes;
/// 源读取完成且魔数预检通过(可裁剪)。
bool _ready = false;
/// 包内解析完成(CropStatus.ready;完成按钮需等解析完再开放)。
bool _cropReady = false;
/// 源读取失败或预检不通过(HEIC 等不支持的格式)。
bool _unsupported = false;
/// 编码落盘中(遮罩 + 防重复点击)。
bool _processing = false;
@override
void initState() {
super.initState();
_sourceBytes = File(widget.sourcePath).readAsBytes();
_sourceBytes
.then((bytes) {
if (!mounted) {
return;
}
setState(() {
_ready = _hasSupportedSignature(bytes);
_unsupported = !_ready;
});
})
.catchError((Object _) {
if (!mounted) {
return;
}
setState(() => _unsupported = true);
});
}
void _cancel() {
Navigator.of(context).pop(null);
}
void _confirm() {
if (_processing || !_ready || !_cropReady) {
return;
}
setState(() => _processing = true);
// crop() 为 void:结果经 onCropped 回调。
_controller.crop();
}
/// 包内状态回调:解析完成(ready)才允许确认,防 crop() 在解析前触发的断言。
void _onCropStatus(CropStatus status) {
final ready = status == CropStatus.ready;
if (ready == _cropReady) {
return;
}
setState(() => _cropReady = ready);
}
Future<void> _onCropped(CropResult result) async {
if (!mounted) {
return;
}
if (result is! CropSuccess) {
_fail();
return;
}
// 仅捕获可发送值(Uint8List/int),闭包跨 isolate 复制。
final cropped = result.croppedImage;
final maxWidth = widget.maxOutputWidth;
try {
final outputPath = await Isolate.run(
() => _encodeCropToJpeg(cropped, maxWidth),
);
if (!mounted) {
return;
}
Navigator.of(context).pop(outputPath);
} on Object {
if (!mounted) {
return;
}
_fail();
}
}
/// 裁剪/编码失败:解除遮罩 + 提示,不 pop。
void _fail() {
setState(() => _processing = false);
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(
content: Text(AppLocalizations.of(context).cropUnsupportedFormat),
),
);
}
@override
Widget build(BuildContext context) {
final l10n = AppLocalizations.of(context);
// 编码落盘中拦截系统返回/ AppBar 返回(与底部取消禁用一致)。
return PopScope(
canPop: !_processing,
child: Scaffold(
appBar: AppBar(title: Text(l10n.cropTitle)),
body: Stack(
children: [
Positioned.fill(child: _buildBody(l10n)),
if (_processing)
Positioned.fill(
child: AbsorbPointer(
child: ColoredBox(
color: Colors.black54,
child: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
const CircularProgressIndicator(),
const SizedBox(height: kSpace12),
Text(
l10n.cropProcessing,
style: TextStyle(
color: Theme.of(context).colorScheme.onPrimary,
),
),
],
),
),
),
),
),
],
),
bottomNavigationBar: SafeArea(
child: Padding(
padding: const EdgeInsets.fromLTRB(
kSpace16,
kSpace8,
kSpace16,
kSpace12,
),
child: Row(
children: [
Expanded(
child: TextButton(
onPressed: _processing ? null : _cancel,
child: Text(l10n.cropCancel),
),
),
const SizedBox(width: kSpace12),
Expanded(
child: FilledButton(
onPressed: (_ready && _cropReady && !_processing)
? _confirm
: null,
child: Text(l10n.cropConfirm),
),
),
],
),
),
),
),
);
}
Widget _buildBody(AppLocalizations l10n) {
if (_unsupported) {
return Center(
child: Padding(
padding: const EdgeInsets.all(kSpace16),
child: Text(
l10n.cropUnsupportedFormat,
textAlign: TextAlign.center,
style: Theme.of(context).textTheme.bodyMedium?.copyWith(
color: Theme.of(context).colorScheme.onSurfaceVariant,
),
),
),
);
}
return FutureBuilder<Uint8List>(
future: _sourceBytes,
builder: (context, snapshot) {
if (snapshot.connectionState != ConnectionState.done ||
!snapshot.hasData) {
return const Center(child: CircularProgressIndicator());
}
return Crop(
image: snapshot.data!,
controller: _controller,
onCropped: _onCropped,
onStatusChanged: _onCropStatus,
aspectRatio: widget.aspectRatio,
// 交互模式 + 锁定裁剪框:用户平移/缩放图片适配固定比例框。
interactive: true,
fixCropRect: true,
baseColor: Theme.of(context).colorScheme.surfaceContainerHighest,
progressIndicator: const CircularProgressIndicator(strokeWidth: 2),
);
},
);
}
}