mirror of
https://github.com/venera-app/venera.git
synced 2025-09-27 15:57:25 +00:00
406 lines
11 KiB
Dart
406 lines
11 KiB
Dart
import 'dart:async';
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import 'dart:convert';
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import 'dart:isolate';
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import 'package:venera/foundation/app.dart';
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import 'package:venera/foundation/local.dart';
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import 'package:venera/utils/image.dart';
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import 'package:venera/utils/io.dart';
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import 'package:zip_flutter/zip_flutter.dart';
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typedef DecodeImage = Future<Image> Function(Uint8List data);
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Future<void> _createPdfFromComic({
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required LocalComic comic,
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required String savePath,
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required String localPath,
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required DecodeImage decodeImage,
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}) async {
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var images = <String>[];
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var baseDir = comic.directory.contains('/') || comic.directory.contains('\\')
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? comic.directory
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: FilePath.join(localPath, comic.directory);
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// add cover
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images.add(FilePath.join(baseDir, comic.cover));
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bool multiChapters = comic.chapters != null;
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void reorderFiles(List<FileSystemEntity> files) {
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files.removeWhere(
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(element) => element is! File || element.path.startsWith('cover'));
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files.sort((a, b) {
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var aName = (a as File).name;
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var bName = (b as File).name;
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var aNumber = int.tryParse(aName);
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var bNumber = int.tryParse(bName);
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if (aNumber != null && bNumber != null) {
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return aNumber.compareTo(bNumber);
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}
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return aName.compareTo(bName);
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});
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}
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if (!multiChapters) {
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var files = Directory(baseDir).listSync();
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reorderFiles(files);
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for (var file in files) {
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images.add(file.path);
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}
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} else {
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for (var chapter in comic.chapters!.keys) {
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var files = Directory(FilePath.join(baseDir, chapter)).listSync();
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reorderFiles(files);
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for (var file in files) {
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images.add(file.path);
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}
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}
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}
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var generator = PdfGenerator(
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title: comic.title,
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author: comic.subtitle,
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imagePaths: images,
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outputPath: savePath,
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decodeImage: decodeImage,
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);
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await generator.generate();
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}
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Future<Isolate> _runIsolate(
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LocalComic comic, String savePath, SendPort sendPort) {
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var localPath = LocalManager().path;
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return Isolate.spawn<SendPort>(
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(sendPort) => overrideIO(
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() async {
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var receivePort = ReceivePort();
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sendPort.send(receivePort.sendPort);
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Completer<Image>? completer;
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Future<Image> decodeImage(Uint8List data) async {
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if (completer != null) {
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throw Exception('Another image is being decoded');
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}
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sendPort.send(data);
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completer = Completer();
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return completer!.future;
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}
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receivePort.listen((message) {
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if (message is Image) {
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if (completer == null) {
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throw Exception('No image is being decoded');
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}
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completer!.complete(message);
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completer = null;
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}
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});
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await _createPdfFromComic(
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comic: comic,
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savePath: savePath,
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localPath: localPath,
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decodeImage: decodeImage,
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);
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sendPort.send(null);
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},
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),
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sendPort,
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);
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}
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Future<void> createPdfFromComicIsolate({
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required LocalComic comic,
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required String savePath,
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}) async {
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var receivePort = ReceivePort();
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SendPort? sendPort;
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Isolate? isolate;
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var completer = Completer<void>();
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receivePort.listen((message) {
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if (message is SendPort) {
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sendPort = message;
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} else if (message is Uint8List) {
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Image.decodeImage(message).then((image) {
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sendPort!.send(image);
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});
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} else if (message == null) {
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receivePort.close();
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completer.complete();
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isolate!.kill();
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}
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});
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isolate = await _runIsolate(comic, savePath, receivePort.sendPort);
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return completer.future;
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}
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class PdfGenerator {
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final String title;
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final String author;
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final List<String> imagePaths;
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final String outputPath;
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final DecodeImage decodeImage;
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// PDF文件的对象ID计数器
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int _objectId = 1;
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// 存储每个对象在PDF中的字节位置
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final Map<int, int> _objectOffsets = {};
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static const double a4Width = 595.0; // points
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static const double a4Height = 842.0; // points
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PdfGenerator({
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required this.title,
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required this.author,
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required this.imagePaths,
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required this.outputPath,
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required this.decodeImage,
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});
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Future<void> generate() async {
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var file = File(outputPath);
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final output = file.openWrite();
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int length = 0;
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void write(String str) {
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var data = utf8.encode(str);
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output.add(data);
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length += data.length;
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}
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void writeData(Uint8List data) {
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output.add(data);
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length += data.length;
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}
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int getCurrentLength() {
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return length;
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}
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// 1. 写入PDF头部
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write('%PDF-1.7\n%\xFF\xFF\xFF\xFF\n\n');
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// 2. 写入Catalog对象
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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write('/Type /Catalog\n');
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write('/Pages ${_objectId + 1} 0 R\n');
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write('>>\nendobj\n\n');
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final catalogId = _objectId++;
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// 3. 写入Pages对象
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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write('/Type /Pages\n');
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write('/Kids [');
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final pageIds = <int>[];
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for (var i = 0; i < imagePaths.length; i++) {
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pageIds.add(_objectId + 1 + i * 3);
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write('${_objectId + 1 + i * 3} 0 R ');
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}
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write(']\n');
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write('/Count ${imagePaths.length}\n');
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write('>>\nendobj\n\n');
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final pagesId = _objectId++;
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// 4. 为每个图片创建Page和Image对象
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for (var i = 0; i < imagePaths.length; i++) {
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final imagePath = imagePaths[i];
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final image = await _getImage(imagePath);
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// 写入Page对象
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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write('/Type /Page\n');
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write('/Parent $pagesId 0 R\n');
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write('/Resources <<\n');
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write('/XObject << /Im${i + 1} ${_objectId + 1} 0 R >>\n');
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write('>>\n');
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write('/MediaBox [0 0 $a4Width $a4Height]\n');
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write('/Contents ${_objectId + 2} 0 R\n');
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write('>>\nendobj\n\n');
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_objectId++;
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// 写入Image对象
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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write('/Type /XObject\n');
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write('/Subtype /Image\n');
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write('/Width ${image.width}\n');
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write('/Height ${image.height}\n');
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write('/ColorSpace /DeviceRGB\n');
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write('/BitsPerComponent 8\n');
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write('/Filter /FlateDecode\n');
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write('/Length ${image.data.length}\n');
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write('>>\nstream\n');
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writeData(image.data);
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write('\nendstream\nendobj\n\n');
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_objectId++;
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// 写入Contents对象（绘制图片的指令）
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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var stream = '';
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stream += 'q\n';
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// Calculate scaling factors
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var scaleX = a4Width / image.width;
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var scaleY = a4Height / image.height;
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var scale = scaleX < scaleY ? scaleX : scaleY;
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// Calculate centering offsets
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var offsetX = (a4Width - (image.width * scale)) / 2;
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var offsetY = (a4Height - (image.height * scale)) / 2;
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// Apply transformation matrix
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stream += '1 0 0 1 $offsetX $offsetY cm\n'; // Translate
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stream += '${scale * image.width} 0 0 ${scale * image.height} 0 0 cm\n';
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stream += '/Im${i + 1} Do\n';
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stream += 'Q\n';
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var streamData = utf8.encode(stream);
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write('/Length ${streamData.length}\n');
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write('>>\nstream\n');
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writeData(streamData);
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write('endstream\nendobj\n\n');
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_objectId++;
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}
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// 5. 写入Info对象（元数据）
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final infoId = _objectId;
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_objectOffsets[_objectId] = getCurrentLength();
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write('$_objectId 0 obj\n');
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write('<<\n');
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write('/Title <');
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writeData(_toPdfString(title));
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write('>\n');
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write('/Author <');
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writeData(_toPdfString(author));
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write('>\n');
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write('/Producer (venera v${App.version})\n');
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write('/CreationDate (D:${_formatDateTime(DateTime.now())})\n');
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write('>>\nendobj\n\n');
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_objectId++;
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// 6. 写入交叉引用表
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final xrefOffset = getCurrentLength();
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write('xref\n');
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write('0 $_objectId\n');
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write('0000000000 65535 f\r\n');
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for (var i = 1; i < _objectId; i++) {
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final offset = _objectOffsets[i]!;
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write('${offset.toString().padLeft(10, '0')} 00000 n\r\n'); // 使用\r\n
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}
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// 7. 写入文件尾部
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write('trailer\n');
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write('<<\n');
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write('/Size $_objectId\n');
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write('/Root $catalogId 0 R\n');
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write('/Info $infoId 0 R\n');
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write('>>\n');
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write('startxref\n');
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write('$xrefOffset\n');
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write('%%EOF\n');
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await output.close();
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}
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int _codeUnitForDigit(int digit) =>
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digit < 10 ? digit + 0x30 : digit + 0x61 - 10;
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Uint8List _toPdfString(String str) {
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Uint8List data;
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try {
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data = latin1.encode(str);
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} catch (e) {
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data = Uint8List.fromList(<int>[0xfe, 0xff] + _encodeUtf16be(str));
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}
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var result = <int>[];
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for (final byte in data) {
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result.add(_codeUnitForDigit((byte & 0xF0) >> 4));
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result.add(_codeUnitForDigit(byte & 0x0F));
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}
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return Uint8List.fromList(result);
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}
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List<int> _encodeUtf16be(String str) {
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const unicodeReplacementCharacterCodePoint = 0xfffd;
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const unicodeByteZeroMask = 0xff;
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const unicodeByteOneMask = 0xff00;
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const unicodeValidRangeMax = 0x10ffff;
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const unicodePlaneOneMax = 0xffff;
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const unicodeUtf16ReservedLo = 0xd800;
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const unicodeUtf16ReservedHi = 0xdfff;
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const unicodeUtf16Offset = 0x10000;
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const unicodeUtf16SurrogateUnit0Base = 0xd800;
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const unicodeUtf16SurrogateUnit1Base = 0xdc00;
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const unicodeUtf16HiMask = 0xffc00;
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const unicodeUtf16LoMask = 0x3ff;
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final encoding = <int>[];
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void add(int unit) {
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encoding.add((unit & unicodeByteOneMask) >> 8);
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encoding.add(unit & unicodeByteZeroMask);
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}
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for (final unit in str.codeUnits) {
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if ((unit >= 0 && unit < unicodeUtf16ReservedLo) ||
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(unit > unicodeUtf16ReservedHi && unit <= unicodePlaneOneMax)) {
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add(unit);
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} else if (unit > unicodePlaneOneMax && unit <= unicodeValidRangeMax) {
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final base = unit - unicodeUtf16Offset;
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add(unicodeUtf16SurrogateUnit0Base +
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((base & unicodeUtf16HiMask) >> 10));
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add(unicodeUtf16SurrogateUnit1Base + (base & unicodeUtf16LoMask));
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} else {
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add(unicodeReplacementCharacterCodePoint);
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}
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}
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return encoding;
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}
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// 格式化日期时间
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String _formatDateTime(DateTime dt) {
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return dt
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.toUtc()
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.toString()
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.replaceAll('-', '')
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.replaceAll(':', '')
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.replaceAll(' ', '')
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.replaceAll('.', '')
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.substring(0, 14);
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}
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Future<({int width, int height, Uint8List data})> _getImage(
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String imagePath) async {
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var data = await File(imagePath).readAsBytes();
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var image = await decodeImage(data);
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var width = image.width;
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var height = image.height;
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data = Uint8List(width * height * 3);
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for (var i = 0; i < width * height; i++) {
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var pixel = image.getPixelAtIndex(i); // RGBA
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data[i * 3] = pixel & 0xFF; // R
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data[i * 3 + 1] = (pixel >> 8) & 0xFF; // G
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data[i * 3 + 2] = (pixel >> 16) & 0xFF; // B
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}
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data = tdeflCompressData(data, true, true, 9);
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return (width: width, height: height, data: data);
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}
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}
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