一、學習筆記

HarmonyOS NEXT API 12

二、實例代碼

將 base64 格式的圖片，轉為PDF

  /**
   * @param mOutputPdfFileName 保存的路徑；例如：getContext().cacheDir +"/"+fileName
   * @param base64Str  base64格式的圖片
   */
  async picConvertPDF(mOutputPdfFileName: string, base64Str: string) {

    let filePath = await base64ImgConvertFilePath(getContext(), base64Str)
    if (filePath == undefined) {
      throw new Error('PDF轉換失敗')
      return
    }

    let pixMap = await uriOrPathConvertPixelMap(filePath)
    if (pixMap == undefined) {
      throw new Error('PDF轉換失敗')
      return
    }
    let imageInfo = await pixMap.getImageInfo()
    let pdfDocument = new pdfService.PdfDocument()
    // 一英寸等于72Points，A4紙的尺寸描述為210 x 297毫米 (8.27 x 11.69英寸)
    let documentWidth = 72 * 8.27
    let documentHeigh = 72 * 11.6
    let createResult = pdfDocument.createDocument(documentWidth, documentHeigh)
    if (createResult) { // 是否成功創建文檔
      let pdfPage: pdfService.PdfPage = pdfDocument.getPage(0);
      // pxConvertInch() 像素轉英寸;
      let imageWidthIn = WindowUtils.pxConvertInch(imageInfo.size.width) * 72
      let imageHeightIn = WindowUtils.pxConvertInch(imageInfo.size.height) * 72
      // 寬度拉滿時，縮放的倍數
      let ratio = documentWidth / imageWidthIn

      pdfPage.addImageObject(
        filePath,
        (documentWidth - imageWidthIn * ratio ) / 2,   // 為了圖片居中
        (documentHeigh - imageHeightIn * ratio) / 2,  // 為了圖片居中
        imageWidthIn * ratio, 
        imageHeightIn * ratio
      )
      pdfDocument.saveDocument(mOutputPdfFileName)
    } else {
      throw new Error('PDF 創建失敗')
      return
    }
  }