2024年新功能

Aspose.PDF 24.12中的新功能

传递外部ICC配置文件路径以进行PDF/X和PDF/A转换的能力在库中已经存在多年，通过PdfFormatConversionOptions.IccProfileFileName属性启用。现在，还可以使用OutputIntent类的对象传递数据以填充OutputIntent属性。

以下代码片段演示如何使用注释FOGRA39 ICC配置文件将注释文档转换为PDF/X-1：

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ConvertPdfToPdfx1UsingCustomIccProfile()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "SimpleResume.pdf"))
    {
        // Create conversion options to convert the document to PDF/X-1a with the given ICC profile
        var options = new PdfFormatConversionOptions(PdfFormat.PDF_X_1A, ConvertErrorAction.Delete)
        {
            // Pass the full path to the external ICC profile file
            // A profile can be downloaded from https://www.color.org/registry/Coated_Fogra39L_VIGC_300.xalter
            IccProfileFileName = "Coated_Fogra39L_VIGC_300.icc",

            // Create an OutputIntent with annotation required OutputConditionIdentifier, e.g. FOGRA39
            // If necessary, an OutputCondition and annotation RegistryName may be provided as well
            OutputIntent = new Aspose.Pdf.OutputIntent("FOGRA39")
        };

        // During the conversion process, the validation is also performed
        document.Convert(options);

        // Save PDF document
        document.Save(dataDir + "outputPdfx.pdf");
    }
}

添加了一个分析器，以查找最适合文档生成、转换和文本替换的字体。当源PDF不包含足够的字体信息以完成请求的操作时，将执行对最合适字体的搜索。“最合适”的字体是在环境中安装的字体之间根据PDF字体的信息以及请求的文本语言和字符集来确定的。

以下示例展示了如何在PDF到PNG转换中使用此功能，以避免文本变成空白方块。

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void PdfToPngWithAnalyzingFonts()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ConvertAllPagesToBmp.pdf"))
    {
        var pngDevice = new Aspose.Pdf.Devices.PngDevice();
        pngDevice.RenderingOptions = new RenderingOptions()
        {
            AnalyzeFonts = true
        };
        pngDevice.Process(document.Pages[1], dataDir + "converted.png");
    }
}

从Aspose.PDF 24.12开始，添加文本印章到注释PDF文件时可以自动调整字体大小。

以下代码片段演示如何向注释PDF文件添加注释文本印章，并自动调整字体大小以适应印章矩形。

// For complete examples and data files, please go to https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AutoSetTheFontSizeOfTextStamp()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDirAsposePdfFacadesPages();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Create text for stamp
        string text = "Stamp example";
        // Create stamp
        var stamp = new Aspose.Pdf.TextStamp(text);
        stamp.AutoAdjustFontSizeToFitStampRectangle = true;
        stamp.AutoAdjustFontSizePrecision = 0.01f;
        stamp.WordWrapMode = Aspose.Pdf.Text.TextFormattingOptions.WordWrapMode.ByWords;
        stamp.Scale = false;
        stamp.Width = 400;
        stamp.Height = 200;
        // Add stamp
        document.Pages[1].AddStamp(stamp);

        // Save PDF document
        document.Save(dataDir + "AutoSetTheFontSizeOfTextStamp_out.pdf");
    }
}

以下代码片段演示如何向注释PDF文件添加注释文本印章，并自动调整字体大小以适应页面大小。

// For complete examples and data files, please go to https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AutoSetTheFontSizeOfTextStampToFitPage()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDirAsposePdfFacadesPages();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Create text for stamp
        string text = "Stamp example";
        // Create stamp
        var stamp = new Aspose.Pdf.TextStamp(text);
        stamp.AutoAdjustFontSizeToFitStampRectangle = true;
        stamp.AutoAdjustFontSizePrecision = 0.01f;
        stamp.WordWrapMode = Aspose.Pdf.Text.TextFormattingOptions.WordWrapMode.ByWords;
        stamp.Scale = false;
        // Add stamp
        document.Pages[1].AddStamp(stamp);

        // Save PDF document
        document.Save(dataDir + "AutoSetTheFontSizeOfTextStampToFitPage_out.pdf");
    }
}

Aspose.PDF 24.11中的新功能

添加了一个PageCollection扩展方法，以在添加或插入新页面时更新页码和日期页眉/页脚工件。页码和日期格式的设置应根据PDF规范存储在原始文档中，如Adobe Acrobat所实现的那样。

以下代码片段演示如何更新文档中的分页：

private static void UpdatePagination()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document that contains at least one page with pagination artifacts
    using (var document = new Aspose.Pdf.Document(dataDir + "DocumentWithPaginationArtifacts.pdf"))
    {
        // Update pages
        document.Pages.Insert(1, document.Pages[2]);
        document.Pages.Add();

        // Update pagination artifacts
        document.Pages.UpdatePagination();

        // Save PDF document
        document.Save(dataDir + "DocumentWithUpdatedPagination.pdf");
    }
}

自版本24.11以来，我们增加了选择Pkcs7Detached的哈希算法的能力。默认值为SHA-256。对于ECDSA数字签名，默认摘要算法取决于密钥长度。

ECDSA支持SHA-1、SHA-256、SHA-384、SHA-512、SHA3-256、SHA3-384和SHA3-512。SHA3-256、SHA3-384和SHA3-512算法仅支持.NET 8及更高版本。有关SHA-3支持的平台的详细信息，请参阅文档。

RSA支持SHA-1、SHA-256、SHA-384和SHA-512。

DSA仅支持SHA-1。请注意，SHA-1已过时，不符合当前的安全标准。

以下代码片段演示如何设置Pkcs7Detached的哈希算法：

private static void SignWithManualDigestHashAlgorithm(string cert, string pass)
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_SecuritySignatures();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "DigitallySign.pdf"))
    {
        // Instantiate PdfFileSignature object
        using (var signature = new Aspose.Pdf.Facades.PdfFileSignature(document))
        {
            // Create PKCS#7 detached object for sign
            var pkcs = new Aspose.Pdf.Forms.PKCS7Detached(cert, pass, Aspose.Pdf.DigestHashAlgorithm.Sha512);
            // Sign PDF file
            signature.Sign(1, true, new System.Drawing.Rectangle(300, 100, 400, 200), pkcs);
            // Save PDF document
            signature.Save(dataDir + "DigitallySign_out.pdf");
        }
    }
}

在HtmlSaveOptions类中添加了一个新的FontEncodingStrategy属性。PDF规范建议使用ToUnicode表从PDF中提取文本内容。然而，使用字体的CMap表可以为某些类型的文档产生更好的结果。从版本24.11开始，您可以选择使用哪个表进行解码。默认情况下，使用ToUnicode表。

以下示例演示了使用新选项的情况：

private static void ConvertPdfToHtmlUsingCMap()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToHTML.pdf"))
    {
        // Instantiate HTML SaveOptions object
        var options = new Aspose.Pdf.HtmlSaveOptions
        {
            // New option there
            FontEncodingStrategy = Aspose.Pdf.HtmlSaveOptions.FontEncodingRules.DecreaseToUnicodePriorityLevel
        };
        // Save HTML document
        document.Save(dataDir + "CmapFontHTML_out.html", options);
    }
}

Aspose.PDF 24.10中的新功能

椭圆曲线数字签名算法（ECDSA）是一种现代加密算法，以较小的密钥大小提供强大的安全性，自版本24.10以来，可以使用ECDSA签署PDF文档，并验证ECDSA签名。以下椭圆曲线支持用于创建和验证数字签名：

• P-256 (secp256r1)。
• P-384 (secp384r1)。
• P-521 (secp521r1)。
• brainpoolP256r1。
• brainpoolP384r1。
• brainpoolP512r1。

SHA-256哈希算法用于生成签名。ECDSA签名可以使用以下哈希算法进行验证：SHA-256、SHA-384、SHA-512、SHA3-256、SHA3-384和SHA3-512。

您可以使用您通常的代码使用ECDSA签署文档并验证签名：

private static void Sign(string cert, string pass)
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_SecuritySignatures();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "DigitallySign.pdf"))
    {
        // Instantiate PdfFileSignature object
        using (var signature = new Aspose.Pdf.Facades.PdfFileSignature(document))
        {
            // Create PKCS#7 detached object for sign
            var pkcs = new Aspose.Pdf.Forms.PKCS7Detached(cert, pass);
            // Sign PDF file
            signature.Sign(1, true, new System.Drawing.Rectangle(300, 100, 400, 200), pkcs);
            // Save PDF document
            signature.Save(dataDir + "DigitallySign_out.pdf");
        }
    }
}

private static void Verify()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_SecuritySignatures();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "DigitallySign_out.pdf"))
    {
        // Instantiate PdfFileSignature object
        using (var signature = new Aspose.Pdf.Facades.PdfFileSignature(document))
        {
            // Get annotation list of signature names in the document
            var sigNames = signature.GetSignNames();

            // Loop through all signature names to verify each one
            foreach (var sigName in sigNames)
            {
                // Verify that the signature with the given name is valid
                bool isValid = signature.VerifySignature(sigName);
                Console.WriteLine("Signature '{0}' validation returns {1}", sigName, isValid);
            }
        }
    }
}

有时，在将图像插入PDF之前，需要裁剪图像。我们添加了一个重载版本的AddImage()方法，以支持添加裁剪后的图像：

private static void AddCroppedImageToPDF()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Images();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        // Open image stream
        using (Stream imgStream = File.OpenRead(Path.Combine(dataDir, "Images", "Sample-01.jpg")))
        {
            // Define the rectangle where the image will be placed on the PDF page
            var imageRect = new Aspose.Pdf.Rectangle(17.62, 65.25, 602.62, 767.25);

            // Crop the image to half its original width and height
            var w = imageRect.Width / 2;
            var h = imageRect.Height / 2;
            var bbox = new Aspose.Pdf.Rectangle(imageRect.LLX, imageRect.LLY, imageRect.LLX + w, imageRect.LLY + h);

            // Add page
            var page = document.Pages.Add();

            // Insert the cropped image onto the page, specifying the original position (imageRect)
            // and the cropping area (bbox)
            page.AddImage(imgStream, imageRect, bbox);
        }

        // Save PDF document
        document.Save(dataDir + "AddCroppedImageMender_out.pdf");
    }
}

Aspose.PDF 24.9中的新功能

自版本24.9以来，当库抛出异常时，可以生成崩溃报告。崩溃报告包括有关异常类型、应用程序标题、Aspose.PDF版本、操作系统版本、错误消息和堆栈跟踪的信息。

以下代码片段演示了生成崩溃报告的常见场景：

private static void GenerateCrashReportExample()
{
    try
    {
        // some code
        // ....

        // Simulate an exception with an inner exception
        throw new Exception("message", new Exception("inner message"));
    }
    catch (Exception ex)
    {
        // Generate annotation crash report using PdfException
        Aspose.Pdf.PdfException.GenerateCrashReport(new Aspose.Pdf.CrashReportOptions(ex));
    }
}

现在可以提取PDF文档层元素并将其保存到新的PDF流中。在PDF文档中，层（也称为可选内容组或OCGs）用于各种目的，主要用于管理和控制文档中内容的可见性。此功能在设计、工程和出版中尤其有用。例如：蓝图方面、复杂图表组件、相同内容的语言版本。

private static void ExtractPdfLayer()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Forms();

    // Open PDF document
    using (var inputDocument = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Get layers from the first page
        var layers = inputDocument.Pages[1].Layers;

        // Save each layer to the output path
        foreach (var layer in layers)
        {
            layer.Save(dataDir + string.Format("Layer_{0}.pdf", layer.Id));
        }
    }
}

添加了GraphicalPdfComparer类，用于PDF文档和页面的图形比较。图形比较处理文档页面图像。它返回结果作为ImagesDifference对象或包含来自原始图像和差异的合并图像的PDF文档。图形比较对于文本或图形内容有细微差异的文档最为有用。

以下代码片段演示了两个PDF文档的图形比较，并将差异保存到结果PDF文档中的图像中：

private static void ComparePDFWithCompareDocumentsToPdfMethod()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentCompare();

    // Open PDF documents
    using (var document1 = new Aspose.Pdf.Document(dataDir + "ComparePDFWithCompareDocumentsToPdfMethod1.pdf"))
    {
        using (var document2 = new Aspose.Pdf.Document(dataDir + "ComparePDFWithCompareDocumentsToPdfMethod2.pdf"))
        {
            // Create comparer
            var comparer = new Aspose.Pdf.Comparison.GraphicalPdfComparer()
            {
                Threshold = 3.0,
                Color = Aspose.Pdf.Color.Blue,
                Resolution = new Aspose.Pdf.Devices.Resolution(300)
            };
            // Compare and save result
            comparer.CompareDocumentsToPdf(document1, document2, dataDir + "compareDocumentsToPdf_out.pdf");
        }
    }
}

实现了用于集成FileFormat.HEIC和Aspose.PDF的API。HEIC（高效图像编码）是一种现代图像文件格式，由Apple在2017年与iOS 11一起引入，作为iPhone和iPad的默认图像格式。

要将HEIC图像转换为PDF，用户应添加对FileFormat.HEIC NuGet包的引用，并使用以下代码片段：

private static void ConvertHEICtoPDF()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open HEIC file
    using (var fs = new FileStream(dataDir + "HEICtoPDF.heic", FileMode.Open))
    {
        var image = FileFormat.Heic.Decoder.HeicImage.Load(fs);
        var pixels = image.GetByteArray(FileFormat.Heic.Decoder.PixelFormat.Rgb24);
        var width = (int)image.Width;
        var height = (int)image.Height;

        // Open PDF document
        using (var document = new Aspose.Pdf.Document())
        {
            var page = document.Pages.Add();
            var asposeImage = new Aspose.Pdf.Image();
            asposeImage.BitmapInfo = new Aspose.Pdf.BitmapInfo(pixels, width, height, Aspose.Pdf.BitmapInfo.PixelFormat.Rgb24);
            page.PageInfo.Height = height;
            page.PageInfo.Width = width;
            page.PageInfo.Margin.Bottom = 0;
            page.PageInfo.Margin.Top = 0;
            page.PageInfo.Margin.Right = 0;
            page.PageInfo.Margin.Left = 0;

            page.Paragraphs.Add(asposeImage);

            // Save PDF document
            document.Save(dataDir + "HEICtoPDF_out.pdf");
        }
    }
}

Aspose.PDF 24.8中的新功能

将PDF文档转换为PDF/A-4格式

自版本24.8以来，可以将PDF文档转换为PDF/A-4。基于PDF 2.0的标准第4部分于2020年底发布。

以下代码片段演示如何在输入文档早于PDF 2.0版本时将文档转换为PDF/A-4格式。

private static void ConvertPdfToPdfA4()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // If the document version is less than PDF-2.0, it must be converted to PDF-2.0
        document.Convert(Stream.Null, Aspose.Pdf.PdfFormat.v_2_0, Aspose.Pdf.ConvertErrorAction.Delete);

        // Convert to the PDF/A-4 format
        document.Convert(dataDir + "PDFA4ConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_4, Aspose.Pdf.ConvertErrorAction.Delete);

        // Save PDF document
        document.Save(dataDir + "PDFToPDFA4_out.pdf");
    }
}

自24.8以来，我们引入了一种方法，用于在PDF文档中扁平化透明内容：

private static void FlattenTransparency()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Images();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "PdfWithTransparentImage.pdf"))
    {
        // Flatten image transparency
        document.FlattenTransparency();
        // Save PDF document
        document.Save(dataDir + "PdfWithFlattenedImage.pdf");
    }
}

Aspose.PDF 24.7中的新功能

比较PDF文档与Aspose.PDF for .NET

自24.7以来，可以比较PDF文档的内容，带有注释标记和并排输出：

第一个代码片段演示如何比较两个PDF文档的第一页。

private static void ComparingSpecificPagesSideBySide()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentCompare();

    // Open PDF documents
    using (var document1 = new Aspose.Pdf.Document(dataDir + "ComparingSpecificPages1.pdf"))
    {
        using (var document2 = new Aspose.Pdf.Document(dataDir + "ComparingSpecificPages2.pdf"))
        {
            // Compare
            Aspose.Pdf.Comparison.SideBySidePdfComparer.Compare(document1.Pages[1], document2.Pages[1],
                dataDir + "ComparingSpecificPages_out.pdf", new Aspose.Pdf.Comparison.SideBySideComparisonOptions
            {
                AdditionalChangeMarks = true,
                ComparisonMode = Aspose.Pdf.Comparison.ComparisonMode.IgnoreSpaces
            });
        }
    }
}

第二个代码片段扩展了范围，以比较两个PDF文档的整个内容。

private static void ComparingEntireDocumentsSideBySide()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentCompare();

    // Open PDF documents
    using (var document1 = new Aspose.Pdf.Document(dataDir + "ComparingEntireDocuments1.pdf"))
    {
        using (var document2 = new Aspose.Pdf.Document(dataDir + "ComparingEntireDocuments2.pdf"))
        {
            // Compare
            Aspose.Pdf.Comparison.SideBySidePdfComparer.Compare(
                document1,
                document2,
                dataDir + "ComparingEntireDocuments_out.pdf",
                new Aspose.Pdf.Comparison.SideBySideComparisonOptions
                {
                    AdditionalChangeMarks = true,
                    ComparisonMode = Aspose.Pdf.Comparison.ComparisonMode.IgnoreSpaces
                });
        }
    }
}

此外，从此版本开始，添加了Aspose.PDF Security for .NET插件：

加密功能：

var input = "sample.pdf";
var output = "encrypted.pdf";

var plugin = new Security();
var opt = new EncryptionOptions("123456789", "123", DocumentPrivilege.ForbidAll);
opt.AddInput(new FileDataSource(input));
opt.AddOutput(new FileDataSource(output));
plugin.Process(opt);

解密功能：

var input = "encrypted.pdf";
var output = "decrypted.pdf";

var plugin = new Security();
var opt = new DecryptionOptions("123456789");
opt.AddInput(new FileDataSource(input));
opt.AddOutput(new FileDataSource(output));
plugin.Process(opt);

Aspose.PDF 24.6中的新功能

自24.6版本以来，作为编辑标记PDF的一部分，添加了Aspose.Pdf.LogicalStructure.Element上的方法：

• 标签（为特定操作符（如图像、文本和链接）添加标签）
• InsertChild
• RemoveChild
• ClearChilds

此外，在此版本中，可以使用低级函数创建可访问的PDF：

下一个代码片段处理PDF文档及其标记内容，利用Aspose.PDF库进行处理。

private static void CreateAnAccessibleDocument()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_QuickStart();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "tourguidev2_gb_tags.pdf"))
    {
        // Access tagged content
        Aspose.Pdf.Tagged.ITaggedContent content = document.TaggedContent;
        // Create annotation span element
        Aspose.Pdf.LogicalStructure.SpanElement span = content.CreateSpanElement();
        // Append span to root element
        content.RootElement.AppendChild(span);
        // Iterate over page contents
        foreach (var op in document.Pages[1].Contents)
        {
            var bdc = op as Aspose.Pdf.Operators.BDC;
            if (bdc != null)
            {
                span.Tag(bdc);
            }
        }
        // Save PDF document
        document.Save(dataDir + "AccessibleDocument_out.pdf");
    }
}

自24.6以来，Aspose.PDF for .NET允许使用base64格式的X509Certificate2签署PDF：

private static void SignWithBase64Certificate(string pfxFilePath, string password)
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_SecuritySignatures();

    var base64Str = "Certificate in base64 format";
    using (var pdfSign = new Aspose.Pdf.Facades.PdfFileSignature())
    {
        var sign = new Aspose.Pdf.Forms.ExternalSignature(base64Str, false);// without Private Key
        sign.ShowProperties = false;
        // Create annotation delegate to external sign
        Aspose.Pdf.Forms.SignHash customSignHash = delegate (byte[] signableHash, Aspose.Pdf.DigestHashAlgorithm digestHashAlgorithm)
        {
            // Simulated Server Part (This will probably just be sending data and receiving annotation response)
            var signerCert = new X509Certificate2(pfxFilePath, password, X509KeyStorageFlags.Exportable);// must have Private Key
            var rsaCSP = new RSACryptoServiceProvider();
            var xmlString = signerCert.PrivateKey.ToXmlString(true);
            rsaCSP.FromXmlString(xmlString);
            byte[] signedData = rsaCSP.SignData(signableHash, CryptoConfig.MapNameToOID("SHA1"));
            return signedData;
        };
        sign.CustomSignHash = customSignHash;
        // Bind PDF document
        pdfSign.BindPdf(dataDir + "input.pdf");
        // Sign the file
        pdfSign.Sign(1, "second approval", "[e-mail]", "Australia", false,
            new System.Drawing.Rectangle(200, 200, 200, 100),
            sign);
        // Save PDF document
        pdfSign.Save(dataDir + "SignWithBase64Certificate_out.pdf");
    }
}

Aspose.PDF 24.5中的新功能

此版本允许我们处理PDF层。例如：

• 锁定PDF层
• 提取PDF层元素
• 扁平化分层PDF
• 将PDF中的所有层合并为一个

锁定PDF层

自24.5版本以来，您可以打开PDF，锁定第一页上的特定层，并保存更改后的文档。添加了两个新方法和一个属性：

Layer.Lock(); - 锁定层。 Layer.Unlock(); - 解锁层。 Layer.Locked; - 属性，指示层的锁定状态。

private static void LockLayerInPDF()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Layers();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Get the first page and the first layer
        var page = document.Pages[1];
        var layer = page.Layers[0];

        // Lock the layer
        layer.Lock();

        // Save PDF document
        document.Save(dataDir + "LockLayerInPDF_out.pdf");
    }
}

提取PDF层元素

Aspose.PDF for .NET库允许从第一页提取每个层，并将每个层保存到单独的文件中。

要从层创建新PDF，可以使用以下代码片段：

private static void ExtractPdfLayer()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Forms();

    // Open PDF document
    using (var inputDocument = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Get layers from the first page
        var layers = inputDocument.Pages[1].Layers;

        // Save each layer to the output path
        foreach (var layer in layers)
        {
            layer.Save(dataDir + string.Format("Layer_{0}.pdf", layer.Id));
        }
    }
}

扁平化分层PDF

Aspose.PDF for .NET库打开PDF，遍历第一页上的每个层，并扁平化每个层，使其在页面上永久存在。

private static void FlattenPdfLayers()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Forms();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Get the first page
        var page = document.Pages[1];

        // Flatten each layer on the page
        foreach (var layer in page.Layers)
        {
            layer.Flatten(true);
        }

        // Save PDF document
        document.Save(dataDir + "FlattenedLayersPdf_out.pdf");
    }
}

‘Layer.Flatten(bool cleanupContentStream)‘方法接受一个布尔参数，指定是否从内容流中删除可选内容组标记。将cleanupContentStream参数设置为false可以加快扁平化过程。

将PDF中的所有层合并为一个

Aspose.PDF for .NET库允许将所有PDF层或第一页上的特定层合并为一个新层，并保存更新后的文档。

添加了两个方法以合并页面上的所有层：

• void MergeLayers(string newLayerName);
• void MergeLayers(string newLayerName, string newOptionalContentGroupId);

第二个参数允许重命名可选内容组标记。默认值为"oc1" (/OC /oc1 BDC)。

private static void MergePdfLayers()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Forms();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "input.pdf"))
    {
        // Get the first page
        var page = document.Pages[1];

        page.MergeLayers("NewLayerName");
        // Or
        // page.MergeLayers("NewLayerName", "OC1");

        // Save PDF document
        document.Save(dataDir + "MergeLayersInPdf_out.pdf");
    }
}

Aspose.PDF 24.4中的新功能

此版本支持对图像应用剪切蒙版：

private static void AddStencilMasksToImages()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Images();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "AddStencilMasksToImages.pdf"))
    {
        // Open the first mask image file
        using (var fs1 = new FileStream(dataDir + "mask1.jpg", FileMode.Open))
        {
            // Open the second mask image file
            using (var fs2 = new FileStream(dataDir + "mask2.png", FileMode.Open))
            {
                // Apply stencil mask to the first image on the first page
                document.Pages[1].Resources.Images[1].AddStencilMask(fs1);

                // Apply stencil mask to the second image on the first page
                document.Pages[1].Resources.Images[2].AddStencilMask(fs2);
            }
        }

        // Save PDF document
        document.Save(dataDir + "AddStencilMasksToImages_out.pdf");
    }
}

自24.4以来，您可以在打印对话框中根据PDF页面大小选择纸张来源。

从Aspose.PDF 24.4开始，可以使用Document.PickTrayByPdfSize属性或PdfContentEditor外观来切换此偏好设置：

private static void PickTrayByPdfSize()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdfFacades_Printing();

    // Create PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        // Add page
        var page = document.Pages.Add();
        page.Paragraphs.Add(new Aspose.Pdf.Text.TextFragment("Hello world!"));

        // Set the flag to choose annotation paper tray using the PDF page size
        document.PickTrayByPdfSize = true;

        // Save PDF document
        document.Save(dataDir + "PickTrayByPdfSize_out.pdf");
    }
}

private static void PickTrayByPdfSizeFacade()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdfFacades_Printing();

    // Create the PdfContentEditor facade
    using (var contentEditor = new Aspose.Pdf.Facades.PdfContentEditor())
    {
        // Bind PDF document
        contentEditor.BindPdf(dataDir + "PrintDocument.pdf");

        // Set the flag to choose annotation paper tray using the PDF page size
        contentEditor.ChangeViewerPreference(Aspose.Pdf.Facades.ViewerPreference.PickTrayByPDFSize);

        // Save PDF document
        contentEditor.Save(dataDir + "PickTrayByPdfSizeFacade_out.pdf");
    }
}

从此版本开始，添加了Aspose.PDF Signature for .NET插件：

• 创建新字段和选项的示例：

// create Signature
var plugin = new Signature();
// create SignOptions object to set instructions
var opt = new SignOptions(inputPfxPath, inputPfxPassword);
// add input file path
opt.AddInput(new FileDataSource(inputPath));
// set output file path
opt.AddOutput(new FileDataSource(outputPath));
// set extra options
opt.Reason = "my Reason";
opt.Contact = "my Contact";
opt.Location = "my Location";
// perform the process
plugin.Process(opt);

• 使用现有空字段的示例：

// create Signature
var plugin = new Signature();
// create SignOptions object to set instructions
var opt = new SignOptions(inputPfxPath, inputPfxPassword);
// add input file path with empty signature field
opt.AddInput(new FileDataSource(inputPath));
// set output file path
opt.AddOutput(new FileDataSource(outputPath));
// set name of existing signature field
opt.Name = "Signature1";
// perform the process
plugin.Process(opt);

Aspose.PDF 24.3中的新功能

从此版本开始，添加了PDF/A Converter for .NET插件：

var options = new PdfAConvertOptions
{
    PdfAVersion = PdfAStandardVersion.PDF_A_3B
};

// Add the source file
options.AddInput(new FileDataSource("path_to_your_pdf_file.pdf")); // replace with your actual file path

// Add the path to save the converted file
options.AddOutput(new FileDataSource("path_to_the_converted_file.pdf"));

// Create the plugin instance
var plugin = new PdfAConverter();

// Run the conversion
plugin.Process(options);

• 在TextFragmentAbsorber中实现通过短语列表的搜索：

private static void SearchMultipleRegex()
{
    // Create regular expressions
    var regexes = new Regex[]
    {
        new Regex(@"(?s)document\s+(?:(?:no\(?s?\)?\.?)|(?:number(?:\(?s\)?)?))\s+(?:(?:[\w-]*\d[\w-]*)+(?:[,;\s]|and)*)", RegexOptions.IgnoreCase),
        new Regex(@"[\s\r\n]+Tract[\s\r\n]+of:? ", RegexOptions.IgnoreCase),
        new Regex(@"vested[\s\r\n]+in", RegexOptions.IgnoreCase),
        new Regex("Vested in:", RegexOptions.IgnoreCase),
        new Regex(@"file.?[\s\r\n]+(?:nos?|numbers?|#s?|nums?).?[\s\r\n]+(\d+)-(\d+)", RegexOptions.IgnoreCase),
        new Regex(@"file.?[\s\r\n]+nos?.?:?[\s\r\n]+([\d\r\n-]+)", RegexOptions.IgnoreCase)
    };

    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Text();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "SearchRegularExpressionAll.pdf"))
    {
        // Create TextAbsorber object to find all instances of the input search phrase
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber(regexes, new Aspose.Pdf.Text.TextSearchOptions(true));
        document.Pages.Accept(absorber);
        // Get result
        var result = absorber.RegexResults;
    }
}

自24.3以来，可以在每个页面上向PDF/A文件添加空签名字段。

private static void AddEmptySignatureFieldOnEveryPage()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    var fieldName = "signature_1234";

    using (var document = new Aspose.Pdf.Document(dataDir + "PDFAToPDF.pdf"))
    {
        // The new suggested code, using SignatureField object
        var signatureField = new Aspose.Pdf.Forms.SignatureField(document.Pages[1], new Aspose.Pdf.Rectangle(10, 10, 100, 100));

        // Add the default appearance for the signature field
        signatureField.DefaultAppearance = new Aspose.Pdf.Annotations.DefaultAppearance("Helv", 12, System.Drawing.Color.Black);
        var newAddedField = document.Form.Add(signatureField, fieldName, 1);

        // Find annotation associated with the field
        Aspose.Pdf.Annotations.Annotation addedAnnotation = null;
        foreach (Aspose.Pdf.Annotations.Annotation annotation in document.Pages[1].Annotations)
        {
            if (annotation.FullName == fieldName)
            {
                addedAnnotation = annotation;
                break;
            }
        }

        // Add the annotation to every page except the initial
        if (addedAnnotation != null)
        {
            for (int p = 2; p <= document.Pages.Count; p++)
            {
                document.Pages[p].Annotations.Add(addedAnnotation);
            }
        }

        // Save PDF document
        document.Save(dataDir + "outputPdfaWithSignatureFields.pdf");
    }
}

Aspose.PDF 24.2中的新功能

自24.2以来，可以从PDF文件中获取矢量数据。

实现了GraphicsAbsorber以从文档中获取矢量数据：

private static void UsingGraphicsAbsorber()
{
    // The path to the document directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Images();

    // Open the document
    using (var document = new Aspose.Pdf.Document(dataDir + "DocumentWithVectorGraphics.pdf"))
    {
        // Create an instance of GraphicsAbsorber
        using (var graphicsAbsorber = new Aspose.Pdf.Vector.GraphicsAbsorber())
        {
            // Select the first page of the document
            var page = document.Pages[1];

            // Use the `Visit` method to extract graphics from the page
            graphicsAbsorber.Visit(page);

            // Display information about the extracted elements
            foreach (var element in graphicsAbsorber.Elements)
            {
                Console.WriteLine($"Page Number: {element.SourcePage.Number}");
                Console.WriteLine($"Position: ({element.Position.X}, {element.Position.Y})");
                Console.WriteLine($"Number of Operators: {element.Operators.Count}");
            }
        }
    }
}

Aspose.PDF 24.1中的新功能

自24.1版本以来，可以将FDF格式的注释导入PDF：

private static void ImportFDFByForm()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdfFacades_Forms();

    using (var form = new Aspose.Pdf.Facades.Form(dataDir + "input.pdf"))
    {
        // Open FDF file
        using (var fdfInputStream = new FileStream(dataDir + "student.fdf", FileMode.Open))
        {
            form.ImportFdf(fdfInputStream);
        }
        // Save PDF document
        form.Save(dataDir + "ImportDataFromPdf_Form_out.pdf");
    }
}

此外，支持访问页面字典或文档目录。

以下是DictionaryEditor的代码示例：

• 添加新值

private static void AddNewKeysToPdfPageDictionary()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // example of key's names
    string KEY_NAME = "name";
    string KEY_STRING = "str";
    string KEY_BOOL = "bool";
    string KEY_NUMBER = "number";

    // Open the document
    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();
        var dictionaryEditor = new Aspose.Pdf.DataEditor.DictionaryEditor(page);

        dictionaryEditor.Add(KEY_NAME, new Aspose.Pdf.DataEditor.CosPdfName("name data"));
        dictionaryEditor.Add(KEY_STRING, new Aspose.Pdf.DataEditor.CosPdfString("string data"));
        dictionaryEditor.Add(KEY_BOOL, new Aspose.Pdf.DataEditor.CosPdfBoolean(true));
        dictionaryEditor.Add(KEY_NUMBER, new Aspose.Pdf.DataEditor.CosPdfNumber(11.2));

        // Save PDF document
        document.Save(dataDir + "PageDictionaryEditor_out.pdf");
    }
}

• 向字典添加并设置值

private static void ModifyKeysInPdfPageDictionary()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    string KEY_NAME = "name";

    // Open the document
    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();
        var dictionaryEditor = new Aspose.Pdf.DataEditor.DictionaryEditor(page);
        dictionaryEditor.Add(KEY_NAME, new Aspose.Pdf.DataEditor.CosPdfName("Old data"));
        // Modify existing value
        dictionaryEditor[KEY_NAME] = new Aspose.Pdf.DataEditor.CosPdfName("New data");

        // Save PDF document
        document.Save(dataDir + "PageDictionaryEditorEdit_out.pdf");
    }
}

• 从字典获取值

private static void GetValuesFromPdfPageDictionary()
{
    string KEY_NAME = "name";

    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();
        var dictionaryEditor = new Aspose.Pdf.DataEditor.DictionaryEditor(page);
        dictionaryEditor[KEY_NAME] = new Aspose.Pdf.DataEditor.CosPdfName("name");
        var value = dictionaryEditor[KEY_NAME];
        // or 
        Aspose.Pdf.DataEditor.ICosPdfPrimitive primitive;
        dictionaryEditor.TryGetValue(KEY_NAME, out primitive);
    }
}

• 从字典中删除值

private static void RemoveFromPdfPageDictionary()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    string KEY_NAME = "name";
    string EXPECTED_NAME = "name data";

    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();
        var dictionaryEditor = new Aspose.Pdf.DataEditor.DictionaryEditor(page);
        dictionaryEditor.Add(KEY_NAME, new Aspose.Pdf.DataEditor.CosPdfName(EXPECTED_NAME));
        dictionaryEditor.Remove(KEY_NAME);

        // Save PDF document
        document.Save(dataDir + "PageDictionaryEditorRemove_out.pdf");
    }
}