PDF/UA,即Universally Accessible PDF,该格式的PDF文件是于2012年8月以ISO标准14289-1发布的、具有普遍可访问的PDF文档标准。为带标签的PDF文档(Tagged PDF Document)和表单的开发人员和作者设定了明确的规则。(PDF/UA-1是作为PDF/UA标准的第一部分,PDF/UA-2作为PDF/UA标准的第二部分)[1]2.文件格式要求
PDF/UA文件作为PDF文件的一种标准格式,要创建该标准的的PDF文档,可使用调用PDF API的方法来创建。下面,是以Spire.PDF for .NET来创建的方法。注:可在Visual Studio 中通过NuGet搜索“Spire.PDF”安装dll到程序中;或者下载包(hotfix版本)到本地,手动添加本地路径下的Spire.Pdf.dll文件到程序。C#
using Spire.Pdf;
using Spire.Pdf.Graphics;
using Spire.Pdf.Interchange.TaggedPdf;
using System.Drawing;
namespace CreatePDFUAfile
{
class Program
{
static void Main(string[] args)
{
//创建PdfDocument类的对象
PdfDocument doc = new PdfDocument();
//添加一页
doc.Pages.Add();
//设置tab order
doc.Pages[0].SetTabOrder(TabOrder.Structure);
//创建PdfTaggedContent类的对象
PdfTaggedContent taggedContent = new PdfTaggedContent(doc);
taggedContent.SetLanguage("en-US");
taggedContent.SetTitle("test");
//设置PDF/UA1验证
taggedContent.SetPdfUA1Identification();
//创建字体、画刷
PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Times New Roman", 10), true);
PdfSolidBrush brush = new PdfSolidBrush(Color.Black);
Dim font As New PdfTrueTypeFont(New Font("Times New Roman", 10), True)
Dim brush As New PdfSolidBrush(Color.Black)
'添加要素
Dim article As PdfStructureElement = taggedContent.StructureTreeRoot.AppendChildElement(PdfStandardStructTypes.Document)
Dim paragraph1 As PdfStructureElement = article.AppendChildElement(PdfStandardStructTypes.Paragraph)
Dim span1 As PdfStructureElement = paragraph1.AppendChildElement(PdfStandardStructTypes.Span)
span1.BeginMarkedContent(doc.Pages(0))
Dim format As New PdfStringFormat(PdfTextAlignment.Justify)
doc.Pages(0).Canvas.DrawString("PDF/UA was published as ISO Standard 14289-1 in August 2012" + " and is by far the first complete definition " + "of a set of requirements for universally accessible PDF documents.", font, brush, New Rectangle(40, 80, 450, 80), format)
span1.EndMarkedContent(doc.Pages(0))
Dim paragraph2 As PdfStructureElement = article.AppendChildElement(PdfStandardStructTypes.Paragraph)
paragraph2.BeginMarkedContent(doc.Pages(0))
doc.Pages(0).Canvas.DrawString("The PDF/UA has some definite requirements at its base that act as the essence of this standard.", font, brush, New Rectangle(40, 120, 450, 60), format)
paragraph2.EndMarkedContent(doc.Pages(0))
Dim figure1 As PdfStructureElement = article.AppendChildElement(PdfStandardStructTypes.Figure)
'Set Alternate text
figure1.Alt = "replacement text1"
figure1.BeginMarkedContent(doc.Pages(0), Nothing)
Dim image As PdfImage = PdfImage.FromFile("logo.jpg")
doc.Pages(0).Canvas.DrawImage(image, New PointF(40, 200), New SizeF(100, 100))
figure1.EndMarkedContent(doc.Pages(0))
Dim figure2 As PdfStructureElement = article.AppendChildElement(PdfStandardStructTypes.Figure)
'Set Alternate text
figure2.Alt = "replacement text2"
figure2.BeginMarkedContent(doc.Pages(0), Nothing)
doc.Pages(0).Canvas.DrawRectangle(PdfPens.Black, New Rectangle(300, 200, 100, 100))