HarmonyOS 应用开发日记：PDF Kit 在美颜相机中的文档处理方案

开发场景需求在"拍摄美颜相机"应用中，PDF Kit 实现：照片转 PDF：将多张照片合并为可打印文档文档美化：为 PDF 添加艺术边框和水印智能 OCR：识别图片中的文字生成可搜索 PDF

// 核心实现与代码示例// 照片转PDF文档// 基础PDF创建：typescript

import pdf from '@ohos.pdf';

// 创建新PDF文档const doc = pdf.createDocument({title: '我的摄影作品集',author: this.userName,pageSize: 'A4' // 标准A4尺寸});

// 添加照片页面async function addPhotoPage(imagePath) {const page = doc.addPage();await page.drawImage(imagePath, {x: 50, y: 50,width: 500, // 固定宽度maintainAspectRatio: true});

// 添加拍摄信息const meta = await MediaLibrary.getImageInfo(imagePath);page.drawText(拍摄于: ${meta.date.toLocaleDateString()},{ x: 50, y: 30 });}

// 批量处理示例photoPaths.forEach(addPhotoPage);await doc.save('/sdcard/MyPhotos.pdf');// 多图排版优化：typescript

// 九宫格布局PDFfunction createCollagePDF(images) {const gridSize = 3;const pageWidth = 595; // A4 pts单位const cellSize = pageWidth / gridSize;

images.forEach((img, index) => {if (index % (gridSize * gridSize) === 0) {page = doc.addPage();}

const row = Math.floor(index / gridSize) % gridSize;const col = index % gridSize;
page.drawImage(img, {  x: col * cellSize + 5,  y: pageHeight - (row + 1) * cellSize + 5,  width: cellSize - 10});

});}// PDF艺术化处理// 水印与边框：typescript

// 添加艺术水印function addWatermark(page) {page.drawText('BeautyCam Pro', {x: 200, y: 400,opacity: 0.2,angle: 45,fontSize: 48,color: '#888888'});}

// 自定义边框function addPhotoFrame(page, imageRect) {page.drawRectangle({...imageRect,inset: -10, // 边框向外扩展borderWidth: 3,borderColor: '#FF2D6A',borderRadius: 8});

// 四角装饰const cornerSize = 15;['tl', 'tr', 'bl', 'br'].forEach(pos => {page.drawVectorGraphic('corner_decor.svg', {position: pos,size: cornerSize});});}// 智能配色：typescript

// 根据照片主色设置PDF主题async function setThemeColor(page, imagePath) {const dominantColor = await ImageAnalysis.getDominantColor(imagePath);page.setTheme({textColor: getContrastColor(dominantColor),highlightColor: lighten(dominantColor, 20),backgroundColor: darken(dominantColor, 40)});}// OCR文本识别// 图片转可搜索PDF：typescript

import ocr from '@ohos.ocr';

// 创建可搜索PDFasync function createSearchablePDF(imagePath) {const result = await ocr.recognize(imagePath, {outputFormat: 'pdf',languages: ['zh', 'en']});

// 添加原始图片为背景const pdfDoc = pdf.open(result.pdfPath);const firstPage = pdfDoc.getPage(0);firstPage.drawImage(imagePath, {width: firstPage.getWidth(),asBackground: true // 设为背景不影响文字选择});

return pdfDoc.save();}// 文档元数据增强：typescript

// 添加可搜索关键词function enhancePDFMetadata(doc, keywords) {doc.setMetadata({title: 'OCR处理文档',keywords: ['扫描件', ...keywords],creator: '美颜相机OCR工具'});

// 添加书签doc.outline.addItem('识别结果', {pageNumber: 1,viewFit: 'fit-width'});}

// 关键优化策略// 大文件处理typescript

// 分块处理超大PDFasync function processLargePDF(path) {const chunkSize = 10 * 1024 * 1024; // 10MB/块const reader = pdf.createChunkedReader(path, chunkSize);

while (!reader.isDone()) {const chunk = await reader.nextChunk();await this.processChunk(chunk);}}// 隐私保护typescript

// 敏感信息擦除function sanitizePDF(doc) {doc.redact({patterns: [{ regex: '\d{11}', type: 'phone' }, // 手机号{ regex: '\d{18}X?', type: 'id' } // 身份证],replacement: '█'});}// 跨平台兼容typescript

// 确保PDF/A标准兼容function ensureArchiveCompliance(doc) {doc.convertToStandard('PDF/A-2u', {embedFonts: true,colorProfile: 'sRGB'});}

// 权限管理json

// module.json5配置"requestPermissions": [{"name": "ohos.permission.READ_MEDIA","reason": "读取照片生成PDF"},{"name": "ohos.permission.WRITE_PDF","reason": "保存PDF文档"}]// 内存优化typescript

// 限制并发处理const semaphore = new Semaphore(3); // 最多3个并发async function safeProcess(page) {await semaphore.acquire();try {return await processPage(page);} finally {semaphore.release();}}// 版本兼容typescript

// 检查PDF Kit功能支持if (!pdf.features?.includes('advancedOCR')) {this.useBasicTextExtraction();}