573 lines
19 KiB
JavaScript
573 lines
19 KiB
JavaScript
/**
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* PDFExporter.js
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* PDF导出模块
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* 负责将翻译内容导出为PDF文件
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*/
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class PDFExporter {
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constructor(options = {}) {
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this.options = Object.assign({
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fontUrl: 'https://gcore.jsdelivr.net/npm/source-han-sans-cn@1.0.0/SourceHanSansCN-Normal.otf',
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pdfLibUrl: 'https://gcore.jsdelivr.net/npm/pdf-lib@1.17.1/dist/pdf-lib.min.js',
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fontkitUrl: 'https://gcore.jsdelivr.net/npm/@pdf-lib/fontkit@1.1.1/dist/fontkit.umd.min.js',
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bboxNormalizedRange: 1000
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}, options);
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// 库加载状态
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this.pdfLibLoaded = false;
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this.fontkitLoaded = false;
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}
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/**
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* 导出结构化翻译PDF
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* @param {string} originalPdfBase64 - 原始PDF的Base64编码
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* @param {Array} translatedContentList - 翻译内容列表
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* @param {Function} showNotification - 通知函数
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*/
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async exportStructuredTranslation(originalPdfBase64, translatedContentList, showNotification = null) {
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try {
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// 检查是否有翻译数据
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if (!translatedContentList || translatedContentList.length === 0) {
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if (showNotification) {
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showNotification('没有翻译内容可导出', 'warning');
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}
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return;
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}
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// 检查是否有原始PDF数据
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if (!originalPdfBase64) {
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if (showNotification) {
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showNotification('原始PDF数据不可用', 'error');
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}
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return;
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}
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// 显示进度提示
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if (showNotification) {
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showNotification('正在生成译文PDF，请稍候...', 'info');
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}
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// 动态加载 pdf-lib
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if (typeof PDFLib === 'undefined') {
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console.log('[PDFExporter] 正在加载 pdf-lib...');
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await this.loadPdfLib();
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}
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const { PDFDocument, rgb } = PDFLib;
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// 加载原始PDF
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const pdfBytes = this.base64ToUint8Array(originalPdfBase64);
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const pdfDoc = await PDFDocument.load(pdfBytes);
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// 注册 fontkit
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if (typeof fontkit !== 'undefined') {
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pdfDoc.registerFontkit(fontkit);
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console.log('[PDFExporter] fontkit 已注册');
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} else {
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console.warn('[PDFExporter] fontkit 未加载，无法嵌入自定义字体');
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}
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// 加载中文字体
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let font = null;
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try {
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if (typeof fontkit === 'undefined') {
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throw new Error('fontkit 未加载，无法嵌入中文字体');
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}
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console.log('[PDFExporter] 正在加载中文字体...');
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const fontBytes = await fetch(this.options.fontUrl).then(res => {
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if (!res.ok) throw new Error(`HTTP ${res.status}: ${res.statusText}`);
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return res.arrayBuffer();
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});
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font = await pdfDoc.embedFont(fontBytes);
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console.log('[PDFExporter] 中文字体加载成功');
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} catch (fontError) {
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console.error('[PDFExporter] 中文字体加载失败:', fontError);
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if (showNotification) {
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showNotification('中文字体加载失败，无法导出PDF: ' + fontError.message, 'error');
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}
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throw fontError;
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}
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// ✅ 预处理：计算全局字号限制（与Canvas渲染保持一致）
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const fontSizeLimits = this.preprocessPdfFontSizes(pdfDoc, font, translatedContentList);
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// 按页面分组翻译内容
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const pageContentMap = new Map();
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translatedContentList.forEach((item, idx) => {
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if (item.type !== 'text' || !item.text || !item.bbox) return;
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const pageIdx = item.page_idx !== undefined ? item.page_idx : 0;
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if (!pageContentMap.has(pageIdx)) {
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pageContentMap.set(pageIdx, []);
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}
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pageContentMap.get(pageIdx).push({ ...item, originalIndex: idx });
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});
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const BBOX_NORMALIZED_RANGE = this.options.bboxNormalizedRange;
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// 遍历每一页，覆盖翻译文本
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for (const [pageIdx, items] of pageContentMap.entries()) {
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if (pageIdx >= pdfDoc.getPageCount()) continue;
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const page = pdfDoc.getPage(pageIdx);
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const { width: pageWidth, height: pageHeight } = page.getSize();
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// 计算缩放因子
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const scaleX = pageWidth / BBOX_NORMALIZED_RANGE;
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const scaleY = pageHeight / BBOX_NORMALIZED_RANGE;
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console.log(`[PDFExporter] 页面 ${pageIdx}: PDF尺寸=${pageWidth.toFixed(2)}x${pageHeight.toFixed(2)}pt, 缩放比例=${scaleX.toFixed(3)}x${scaleY.toFixed(3)}`);
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// 用白色矩形覆盖原文
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items.forEach(item => {
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const bbox = item.bbox;
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const x = bbox[0] * scaleX;
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const y = pageHeight - (bbox[3] * scaleY);
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const width = (bbox[2] - bbox[0]) * scaleX;
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const height = (bbox[3] - bbox[1]) * scaleY;
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page.drawRectangle({
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x: x,
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y: y,
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width: width,
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height: height,
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color: rgb(1, 1, 1),
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});
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});
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// 绘制翻译文本
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items.forEach(item => {
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const bbox = item.bbox;
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const text = item.text || '';
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if (!text.trim()) return;
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// 计算bbox在PDF坐标系中的位置
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const x = bbox[0] * scaleX;
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const boxWidth = (bbox[2] - bbox[0]) * scaleX;
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const boxHeight = (bbox[3] - bbox[1]) * scaleY;
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const bboxTop = pageHeight - (bbox[1] * scaleY);
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const bboxBottom = pageHeight - (bbox[3] * scaleY);
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// 判断是否为短文本（与TextFittingAdapter保持一致）
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const isShortText = text.length < 50 || (/\n/.test(text) && text.length < 80);
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// 使用文本布局算法（应用全局字号限制）
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const layout = this.calculatePdfTextLayout(font, text, boxWidth, boxHeight, isShortText, fontSizeLimits);
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const { fontSize, lines, lineHeight } = layout;
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const paddingTop = 2;
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const paddingX = 2;
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const availableHeight = boxHeight - paddingTop * 2;
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// 计算总高度并垂直居中
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const totalHeight = lines.length > 0
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? (lines.length - 1) * lineHeight + fontSize
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: 0;
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const yOffset = (availableHeight - totalHeight) / 2;
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// 绘制每一行（PDF坐标系：Y轴从下往上，所以从顶部开始往下绘制）
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lines.forEach((line, lineIdx) => {
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// 从顶部开始，每一行往下偏移
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const lineY = bboxTop - paddingTop - yOffset - (lineIdx * lineHeight);
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if (lineY < bboxBottom || lineY > bboxTop) return;
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page.drawText(line, {
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x: x + paddingX,
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y: lineY,
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size: fontSize,
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font: font,
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color: rgb(0, 0, 0),
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});
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});
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});
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}
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// 生成PDF
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const modifiedPdfBytes = await pdfDoc.save();
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// 创建Blob并下载
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const blob = new Blob([modifiedPdfBytes], { type: 'application/pdf' });
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const timestamp = new Date().toISOString().replace(/[:.]/g, '-').split('T')[0];
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const filename = `translated_${timestamp}.pdf`;
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// 下载文件
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if (typeof saveAs === 'function') {
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saveAs(blob, filename);
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if (showNotification) {
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showNotification('译文PDF导出成功！', 'success');
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}
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} else {
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// 后备方案
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const url = URL.createObjectURL(blob);
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const a = document.createElement('a');
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a.href = url;
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a.download = filename;
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document.body.appendChild(a);
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a.click();
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document.body.removeChild(a);
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URL.revokeObjectURL(url);
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if (showNotification) {
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showNotification('译文PDF导出成功！', 'success');
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}
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}
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} catch (error) {
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console.error('[PDFExporter] 导出PDF失败:', error);
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if (showNotification) {
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showNotification('导出失败: ' + error.message, 'error');
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}
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}
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}
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/**
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* 预处理PDF字号：计算全局字号限制（与TextFittingAdapter算法一致）
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* @param {Object} pdfDoc - pdf-lib文档对象
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* @param {Object} font - pdf-lib字体对象
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* @param {Array} translatedContentList - 翻译内容列表
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* @returns {Object} { shortTextLimit, longTextLimit } 字号限制（单位：pt）
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*/
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preprocessPdfFontSizes(pdfDoc, font, translatedContentList) {
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console.log('[PDFExporter] 开始预处理全局字号（计算百分位数限制）...');
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const startTime = performance.now();
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const BBOX_NORMALIZED_RANGE = this.options.bboxNormalizedRange;
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const allScales = [];
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const allBboxHeights = [];
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// 收集所有段落的最优缩放因子和bbox高度
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translatedContentList.forEach((item, idx) => {
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if (item.type !== 'text' || !item.text || !item.bbox) return;
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const bbox = item.bbox;
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const pageIdx = item.page_idx !== undefined ? item.page_idx : 0;
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if (pageIdx >= pdfDoc.getPageCount()) return;
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const page = pdfDoc.getPage(pageIdx);
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const { width: pageWidth, height: pageHeight } = page.getSize();
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const scaleX = pageWidth / BBOX_NORMALIZED_RANGE;
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const scaleY = pageHeight / BBOX_NORMALIZED_RANGE;
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const boxWidth = (bbox[2] - bbox[0]) * scaleX;
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const boxHeight = (bbox[3] - bbox[1]) * scaleY;
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const text = item.text;
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// 收集bbox高度（用于计算平均值）
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allBboxHeights.push(boxHeight);
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// 检测公式和短文本
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const hasFormula = /\$\$?[\s\S]*?\$\$?/.test(text);
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const isShortText = text.length < 50 || (/\n/.test(text) && text.length < 80);
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// 计算最优缩放（字号/bbox高度）
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const optimalScale = this._calculateOptimalScaleForPdf(font, text, boxWidth, boxHeight, hasFormula);
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// 按字符数加权采样
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const unitCount = Math.max(1, Math.floor(text.length / 10));
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for (let i = 0; i < unitCount; i++) {
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allScales.push(optimalScale);
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}
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});
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// 计算百分位数（缩放因子的百分位数，不是字号）
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const percentile60 = this._calculatePercentile(allScales, 0.60);
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const percentile80 = this._calculatePercentile(allScales, 0.80);
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const result = {
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shortTextLimitScale: percentile80, // 短文本缩放因子上限（80%百分位）
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longTextLimitScale: percentile60 // 长文本缩放因子上限（60%百分位）
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};
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console.log(`[PDFExporter] 预处理完成: 样本数=${allScales.length}`);
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console.log(`[PDFExporter] 百分位数: 60%=${percentile60.toFixed(3)}, 80%=${percentile80.toFixed(3)}, 耗时=${(performance.now() - startTime).toFixed(0)}ms`);
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console.log(`[PDFExporter] 缩放因子限制: 短文本≤${result.shortTextLimitScale.toFixed(3)} (80%分位), 长文本≤${result.longTextLimitScale.toFixed(3)} (60%分位)`);
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return result;
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}
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/**
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* 计算单个段落的最优缩放因子（PDF版本）
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* @private
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*/
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_calculateOptimalScaleForPdf(font, text, boxWidth, boxHeight, hasFormula = false) {
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if (hasFormula) return 0.5; // 公式使用保守缩放
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const isCJK = /[\u4e00-\u9fa5]/.test(text);
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const hasNewlines = /\n/.test(text);
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const textLength = text.length;
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const initialLineSkip = isCJK ? 1.5 : 1.3;
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// 迭代尝试不同缩放因子
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for (const scale of [0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3]) {
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const fontSize = boxHeight * scale;
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const estimatedCharWidth = fontSize * (isCJK ? 1.0 : 0.6);
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const effectiveWidth = boxWidth * 0.9;
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const charsPerLine = Math.max(1, Math.floor(effectiveWidth / estimatedCharWidth));
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const estimatedLines = hasNewlines ? text.split('\n').length : Math.ceil(textLength / charsPerLine);
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const lineHeight = fontSize * initialLineSkip;
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const totalHeight = estimatedLines === 1 ? fontSize * 1.2 : (estimatedLines - 1) * lineHeight + fontSize * 1.2;
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if (totalHeight <= boxHeight) {
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return scale; // 找到第一个可行的缩放
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}
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}
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return 0.3; // 最小缩放
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}
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/**
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* 计算百分位数（线性插值法）
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* @private
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*/
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_calculatePercentile(arr, percentile) {
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if (arr.length === 0) return 0.85; // 默认值
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const sorted = [...arr].sort((a, b) => a - b);
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const index = percentile * (sorted.length - 1);
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const lower = Math.floor(index);
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const upper = Math.ceil(index);
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const weight = index - lower;
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if (lower === upper) {
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return sorted[lower];
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}
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return sorted[lower] * (1 - weight) + sorted[upper] * weight;
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}
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/**
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* 计算PDF文本布局（与Canvas渲染算法一致）
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* @param {Object} font - pdf-lib字体对象
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* @param {string} text - 文本内容
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* @param {number} boxWidth - 区域宽度
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* @param {number} boxHeight - 区域高度
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* @param {boolean} isShortText - 是否为短文本
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* @param {Object} fontSizeLimits - 全局字号限制 { shortTextLimit, longTextLimit }
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* @returns {Object} { fontSize, lines, lineHeight }
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*/
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calculatePdfTextLayout(font, text, boxWidth, boxHeight, isShortText = false, fontSizeLimits = null) {
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// 判断是否为 CJK 语言
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const isCJK = /[\u4e00-\u9fa5]/.test(text);
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// ✅ 使用与Canvas渲染一致的初始行距
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const lineSkip = isCJK ? 1.5 : 1.3;
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// 内边距：对小bbox减少padding避免裁剪
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const paddingTop = boxHeight < 20 ? 0.5 : 2;
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const paddingX = 2;
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const availableHeight = boxHeight - paddingTop * 2;
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const availableWidth = boxWidth - paddingX * 2;
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// 字号范围
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const estimatedSingleLineFontSize = boxHeight * 0.8;
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// 最小字号：动态调整（基于bbox高度）
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let minFontSize;
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if (boxHeight < 20) {
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minFontSize = Math.max(6, boxHeight * 0.35); // 小bbox：最小6px
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} else {
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minFontSize = isShortText ? 10 : 8; // 正常bbox：10px/8px
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}
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let maxFontSize = Math.min(estimatedSingleLineFontSize * 1.5, boxHeight * 1.2);
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// ✅ 应用全局缩放因子限制（与Canvas渲染保持一致）
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if (fontSizeLimits) {
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const limitScale = isShortText ? fontSizeLimits.shortTextLimitScale : fontSizeLimits.longTextLimitScale;
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const limitFontSize = boxHeight * limitScale; // 缩放因子 × bbox高度 = 字号上限
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maxFontSize = Math.min(maxFontSize, limitFontSize);
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}
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const hasNewlines = text.includes('\n');
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const textLength = text.length;
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// 宽度因子
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const widthFactors = (textLength < 20 || hasNewlines)
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? [1.0]
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: [1.0, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70];
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let bestSolution = null;
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// 二分查找最大可用字号
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for (const widthFactor of widthFactors) {
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const effectiveWidth = availableWidth * widthFactor;
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let low = minFontSize;
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let high = maxFontSize;
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let foundFontSize = null;
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let foundLines = null;
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while (high - low > 0.5) {
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const mid = (low + high) / 2;
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const lines = this.wrapTextForPdf(font, text, effectiveWidth, mid);
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const lineHeight = mid * lineSkip;
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// 与Canvas渲染保持一致：最后一行使用 mid * 1.2 留出垂直空间
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const totalHeight = lines.length === 1
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? mid * 1.2
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: (lines.length - 1) * lineHeight + mid * 1.2;
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if (totalHeight <= availableHeight) {
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foundFontSize = mid;
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foundLines = lines;
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low = mid;
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} else {
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high = mid;
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}
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}
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if (foundFontSize && (!bestSolution || foundFontSize > bestSolution.fontSize)) {
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bestSolution = {
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fontSize: foundFontSize,
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widthFactor: widthFactor,
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lines: foundLines,
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lineHeight: foundFontSize * lineSkip
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};
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}
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}
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// 返回最优解
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if (bestSolution) {
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return bestSolution;
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}
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// 后备方案
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const fallbackFontSize = minFontSize;
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const fallbackLineHeight = fallbackFontSize * lineSkip;
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const allLines = this.wrapTextForPdf(font, text, availableWidth, fallbackFontSize);
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const maxLines = Math.floor(availableHeight / fallbackLineHeight);
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const linesToDraw = allLines.slice(0, Math.max(1, maxLines));
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return {
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fontSize: fallbackFontSize,
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lines: linesToDraw,
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lineHeight: fallbackLineHeight,
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widthFactor: 1.0
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};
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||
}
|
||
|
||
/**
|
||
* PDF文本换行（使用pdf-lib字体测量）
|
||
* @param {Object} font - pdf-lib字体对象
|
||
* @param {string} text - 文本内容
|
||
* @param {number} maxWidth - 最大宽度
|
||
* @param {number} fontSize - 字号
|
||
* @returns {Array} 换行后的文本数组
|
||
*/
|
||
wrapTextForPdf(font, text, maxWidth, fontSize) {
|
||
if (!text) return [];
|
||
|
||
const lines = [];
|
||
let currentLine = '';
|
||
|
||
// 按自然断句分段
|
||
const segments = text.split(/([。？！，、；：\n])/);
|
||
|
||
for (let segment of segments) {
|
||
if (!segment) continue;
|
||
|
||
// 标点符号直接加到当前行
|
||
if (/^[。？！，、；：]$/.test(segment)) {
|
||
currentLine += segment;
|
||
continue;
|
||
}
|
||
|
||
// 换行符强制换行
|
||
if (segment === '\n') {
|
||
if (currentLine) {
|
||
lines.push(currentLine);
|
||
currentLine = '';
|
||
}
|
||
continue;
|
||
}
|
||
|
||
// 按字符逐个添加
|
||
for (let i = 0; i < segment.length; i++) {
|
||
const char = segment[i];
|
||
const testLine = currentLine + char;
|
||
const width = font.widthOfTextAtSize(testLine, fontSize);
|
||
|
||
if (width > maxWidth && currentLine.length > 0) {
|
||
lines.push(currentLine);
|
||
currentLine = char;
|
||
} else {
|
||
currentLine = testLine;
|
||
}
|
||
}
|
||
}
|
||
|
||
if (currentLine) {
|
||
lines.push(currentLine);
|
||
}
|
||
|
||
return lines.length > 0 ? lines : [''];
|
||
}
|
||
|
||
/**
|
||
* 动态加载 pdf-lib 库和 fontkit
|
||
*/
|
||
async loadPdfLib() {
|
||
// 加载 pdf-lib
|
||
if (typeof PDFLib === 'undefined') {
|
||
await new Promise((resolve, reject) => {
|
||
const script = document.createElement('script');
|
||
script.src = this.options.pdfLibUrl;
|
||
script.onload = () => {
|
||
console.log('[PDFExporter] pdf-lib 加载成功');
|
||
this.pdfLibLoaded = true;
|
||
resolve();
|
||
};
|
||
script.onerror = (error) => {
|
||
console.error('[PDFExporter] pdf-lib 加载失败:', error);
|
||
reject(new Error('Failed to load pdf-lib library'));
|
||
};
|
||
document.head.appendChild(script);
|
||
});
|
||
}
|
||
|
||
// 加载 fontkit
|
||
if (typeof fontkit === 'undefined') {
|
||
await new Promise((resolve, reject) => {
|
||
const script = document.createElement('script');
|
||
script.src = this.options.fontkitUrl;
|
||
script.onload = () => {
|
||
console.log('[PDFExporter] fontkit 加载成功');
|
||
this.fontkitLoaded = true;
|
||
resolve();
|
||
};
|
||
script.onerror = (error) => {
|
||
console.warn('[PDFExporter] fontkit 加载失败:', error);
|
||
resolve(); // fontkit失败不阻止流程
|
||
};
|
||
document.head.appendChild(script);
|
||
});
|
||
}
|
||
}
|
||
|
||
/**
|
||
* Base64 转 Uint8Array
|
||
* @param {string} base64 - Base64编码字符串
|
||
* @returns {Uint8Array} 字节数组
|
||
*/
|
||
base64ToUint8Array(base64) {
|
||
const binaryString = atob(base64);
|
||
const len = binaryString.length;
|
||
const bytes = new Uint8Array(len);
|
||
for (let i = 0; i < len; i++) {
|
||
bytes[i] = binaryString.charCodeAt(i);
|
||
}
|
||
return bytes;
|
||
}
|
||
}
|
||
|
||
// 导出模块
|
||
if (typeof module !== 'undefined' && module.exports) {
|
||
module.exports = PDFExporter;
|
||
}
|