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在最新版本的 Aspose.Pdf for .NET中，我们的重点是文件格式转换的优化。这其中包括 PDF to HTML, SVG to PDF, PDF to Excel, PDF to DOC, Image to PDF 以及 PDF to Image。

 Aspose.Pdf for .NET 9.4.0 还引入了从HTML, SVG和其他来源单独提取字体的功能。下面这些代码片段就展示了如何实现这个功能：

• 执行从文档提取字体 (使用新的FontAbsorber类)
• 将字体保存到缓存（Font.Save method)
• 将缓存字体传到HTML转换程序(htmlOptions.FontSources)
• 将文档拆分为单独的页面
• 在parallel threads执行每个页面的HTML转换
• 所有的 threads都使用单个字体设置

public void PDFNEWNET_36524_cacheFonts_Sample()
{
Helper.SetLicense();

string inFile = TestSettings.GetInputFile("36524.pdf");

HTMLMultithreadingTester_FontCache_Sample tester = new HTMLMultithreadingTester_FontCache_Sample(inFile);
tester.Run();
}

class HTMLMultithreadingTester_FontCache_Sample
{
public HTMLMultithreadingTester_FontCache_Sample(string inputFile)
{
    inFile = inputFile;
    fileNameOnly = Path.GetFileNameWithoutExtension(inFile);
    testOut = Path.Combine(TestSettings.TestOutput, fileNameOnly);

    // Delete previous output directories
    if (Directory.Exists(testOut))
    {
        string[] files = Directory.GetFiles(testOut, "*.*", SearchOption.AllDirectories);
        foreach (string file in files)
        {
            File.Delete(file);
        }
        string[] directories = Directory.GetDirectories(testOut, "*.*", SearchOption.AllDirectories);
        foreach (string dir in directories)
        {
            Directory.Delete(dir);
        }
    }
    Directory.CreateDirectory(testOut);
}

string inFile;
string testOut;
string fileNameOnly;

public Dictionary outFileNames = new Dictionary();

public void Run()
{
    Helper.SetLicense();

    // Folder that contains pre-generated cached fonts 
    // All the fonts of the document will be placed to this folder and will be passed to each page conversion procedure
    string fontCacheFolder = Path.Combine(testOut, fileNameOnly + "_fonts_preSaved\\");
    string cacheFontFileTemplate = Path.Combine(fontCacheFolder, "font{0}.ttf");

    // Folder that will contain fonts as a result of the conversion procedure
    string fontOutFolder = Path.GetFullPath(Path.Combine(testOut, fileNameOnly + "_fonts\\"));

    // Create our folders
    Directory.CreateDirectory(fontCacheFolder);
    Directory.CreateDirectory(fontOutFolder);

    System.Diagnostics.Stopwatch sw = System.Diagnostics.Stopwatch.StartNew();

    Aspose.Pdf.Document document = new Aspose.Pdf.Document(inFile);
    int pageCount = document.Pages.Count;

    // Find all the fonts of the document
    FontAbsorber fa = new FontAbsorber();
    fa.Visit(document);

    FontCollection fc = fa.Fonts;
    List fontFiles = new List();

    // Save all the fonts in the cache folder
    int fontNum = 0;
    foreach (Pdf.Text.Font font in fc)
    {
        string cacheFontFile = string.Format(cacheFontFileTemplate, fontNum++);

        using (Stream fileStream = File.OpenWrite(cacheFontFile))
        {
            font.Save(fileStream);
        }
        fontFiles.Add(cacheFontFile);
    }

    int pageNumber = 0;
    // Split the document to separate pages to convert them in parallel
    foreach (Page pdfPage in document.Pages)
    {
        using (Document newDocument = new Document())
        {
            newDocument.Pages.Add(pdfPage);
            newDocument.Save(Path.Combine(testOut, String.Format(fileNameOnly + "_page{0}.pdf", pageNumber)));
        }
        pageNumber++;
    }
    document.Dispose();

    // Run conversion threads
    Thread[] threads = new Thread[pageCount];
    ThreadParam[] threadParams = new ThreadParam[pageCount];

    for (int i = 0; i < pageCount; i++)
    {
        threads[i] = new Thread(new ParameterizedThreadStart(Worker));
        threadParams[i] = new ThreadParam(i);
        threadParams[i].fontFiles = fontFiles;
        threads[i].Start(threadParams[i]);
    }

    // Wait threads to finish
    for (int i = 0; i < pageCount; i++)
    {
        threads[i].Join();
    }

    sw.Stop();
    Console.WriteLine(sw.Elapsed.TotalSeconds);
}

private void Worker(Object param)
{
    ThreadParam threadParam = (ThreadParam)param;
    Console.Out.WriteLine("started: " + threadParam.PageNum);

    try
    {
        using (Aspose.Pdf.Document pdfPageDocument = new Aspose.Pdf.Document(Path.Combine(testOut, String.Format(fileNameOnly + "_page{0}.pdf", threadParam.PageNum))))
        {
            Aspose.Pdf.HtmlSaveOptions htmlOptions = new Aspose.Pdf.HtmlSaveOptions();
            htmlOptions.SplitIntoPages = false;
            htmlOptions.FixedLayout = true;
            htmlOptions.FontSavingMode = HtmlSaveOptions.FontSavingModes.AlwaysSaveAsTTF;
            htmlOptions.CompressSvgGraphicsIfAny = false;
            htmlOptions.CustomResourceSavingStrategy = new HtmlSaveOptions.ResourceSavingStrategy(CacheFontsStrategy);

            // addtthe cached fonts as a font sources
            foreach (string fontFile in threadParam.fontFiles)
            {
                htmlOptions.FontSources.Add(new FileFontSource(fontFile));
            }
            htmlOptions.RasterImagesSavingMode = Aspose.Pdf.HtmlSaveOptions.RasterImagesSavingModes.AsExternalPngFilesReferencedViaSvg;

            string outputFileName = Path.GetFullPath(Path.Combine(testOut, String.Format(fileNameOnly + "_page{0}.html", threadParam.PageNum)));
            pdfPageDocument.Save(outputFileName, htmlOptions);

            outFileNames[threadParam.PageNum] = outputFileName;
        }
    }
    catch (Exception ex)
    {
        threadParam.isSuccess = false;
        Console.Out.WriteLine(ex.ToString());
    }
}

class ThreadParam
{
    public ThreadParam(int pageNum)
    {
        this.PageNum = pageNum;
        this.isSuccess = true;
    }
    public int PageNum;
    public List fontFiles;
    public bool isSuccess;
}

static object resourceSavingSync = new object();

/// 
/// Resource saving callback that saves fonts into output folder and builds css links to the fonts
/// 
private string CacheFontsStrategy(SaveOptions.ResourceSavingInfo resourceSavingInfo)
{
    // The callback is performed in parallel threads, so synchronization must be implemented
    lock (resourceSavingSync)
    {
        string fontsFolder = Path.GetFullPath(Path.Combine(testOut, fileNameOnly + "_fonts\\"));
        if (!Directory.Exists(fontsFolder))
            Directory.CreateDirectory(fontsFolder);

        // First path of this method is for saving of font
        if (resourceSavingInfo.ResourceType == SaveOptions.NodeLevelResourceType.Font)
        {
            string outFontFile = fontsFolder + Path.GetFileName(resourceSavingInfo.SupposedFileName);
            System.IO.BinaryReader fontBinaryReader = new BinaryReader(resourceSavingInfo.ContentStream);
            System.IO.File.WriteAllBytes(outFontFile,
                fontBinaryReader.ReadBytes((int)resourceSavingInfo.ContentStream.Length));
            string fontUrl = "../" + fileNameOnly + "_fonts/" + resourceSavingInfo.SupposedFileName;
            return fontUrl;
        }
        resourceSavingInfo.CustomProcessingCancelled = true;
        return null;
    }
}
}

当上述的代码执行时，字体只能独立于输出HTML文件创建一次。

PDF to HTML导出时确认图片格式

在最近的某次更新中我们引入了PDF to HTML导出时确认图片格式的功能。为了实现该功能，我们还介绍了一个新的类namedHtmlSaveOptions.RasterImagesSavingModes。下列代码片段展示了如何选择目标图像格式：

Aspose.Pdf.Document doc = new Document(@"c:\pdftest\36009.pdf");

HtmlSaveOptions options = new HtmlSaveOptions();
options.RasterImagesSavingMode = HtmlSaveOptions.RasterImagesSavingModes.AsEmbeddedPartsOfPngPageBackground;
// Next line is just to make view best for max amount of browsers
// You can coment it out if You will
options.FontSavingMode = HtmlSaveOptions.FontSavingModes.SaveInAllFormats;
doc.Save(@"c:\pdftest\36009.html", options);

执行上述代码后，输出文件夹不会包含任何SVG文件， 只有PNG格式文件（每页一个PNG格式文件）。

PDF to Excel – 将所有页面导出到单张工作簿

Document doc = new Document("Original.pdf");
ExcelSaveOptions options = new ExcelSaveOptions();
// Set this property to true
options.MinimizeTheNumberOfWorksheets = true;
doc.Save("output.xls", options);

依据内容自动调整表格的列宽

为实现该功能，这里引入了一个新的计算方法——ColumnAdjustment ，包含了值 AutoFitToContent:

string outFile = "36916.pdf";
// Added document
Document doc = new Document();
Page page = doc.Pages.Add();
// Create a table object and add it to the paragraphs collection of the section 
Table tab1 = new Table();
page.Paragraphs.Add(tab1);
// Set the column widths and default cell border of the table
tab1.ColumnAdjustment = ColumnAdjustment.AutoFitToContent;
tab1.ColumnWidths = "50 50 50";
tab1.DefaultCellBorder = new BorderInfo(BorderSide.All, 1F);
// Prepare an array of string values to be added to table
string[] data = new string[] { "Sample Text", "8.4", "Its test to set column width as per contnents" };
// Import the contents of the array created in above step
tab1.ImportArray(data, 0, 0, true);
// Save the resultant PDF
doc.Save(outFile);

鼠标悬停显示注释内容

鼠标悬停在图片或文本上，可以弹出窗口注解了：

/*Declaring of parameters*/
// Unique name of annotation
string name = "IMDB0145487";
// Title of popup window
string title = "Spider-Man";
// Description that be in popup window
string comment = "Movie produced in 2002; run length: 121";
// Path to image for that popup window will appeared on mouse over
string imagePath = (TestSettings.GetInputFile("36228.jpg"));
// Position of image on page of document
Aspose.Pdf.Rectangle imageRect = new Aspose.Pdf.Rectangle(2, 700, 97, 840);
// Position of popup on page of document
Aspose.Pdf.Rectangle popupRect = new Aspose.Pdf.Rectangle(90, 610, 235, 710);

/*Document creating*/
Document doc = new Document();
doc.Pages.Add();
// Page for adding of image
Page page = doc.Pages[1];

/*Add image on page*/
// Load image into stream
FileStream imageStream = new FileStream(imagePath, FileMode.Open);
// Add image to Images collection of Page Resources
page.Resources.Images.Add(imageStream);
// Using GSave operator: this operator saves current graphics state
page.Contents.Add(new Operator.GSave());
// Create Rectangle and Matrix objects
Aspose.Pdf.DOM.Matrix matrix =
    new Aspose.Pdf.DOM.Matrix(new double[]
    {
        imageRect.URX - imageRect.LLX, 0, 0, imageRect.URY - imageRect.LLY, imageRect.LLX, imageRect.LLY
    });
// Using ConcatenateMatrix (concatenate matrix) operator: defines how image must be placed
page.Contents.Add(new Operator.ConcatenateMatrix(matrix));
XImage ximage = page.Resources.Images[page.Resources.Images.Count];
// Using Do operator: this operator draws image
page.Contents.Add(new Operator.Do(ximage.Name));
// Using GRestore operator: this operator restores graphics state
page.Contents.Add(new Operator.GRestore());

/*Add text annotation*/
TextAnnotation text = new TextAnnotation(page, imageRect);
text.Name = name;
text.Title = title;
text.Contents = comment;
// This flags must be raised to suppress showing of annotation icon
text.Flags = AnnotationFlags.NoView|AnnotationFlags.ReadOnly;
page.Annotations.Add(text);

/*Add popup annotation*/
PopupAnnotation popup = new PopupAnnotation(page, popupRect);
page.Annotations.Add(popup);

/*Link text and popup annotations*/
text.Popup = popup;
popup.Parent = text;

/*Add button*/
Field field = new ButtonField(page, imageRect);
doc.Form.Add(field);

/*Set ButtonField actions*/
string fieldName = field.PartialName;
string openScript =
    "var t = this.getAnnot(this.pageNum, '" + name + "'); t.popupOpen = true; var w = this.getField('" + fieldName + "'); w.setFocus();";
string closeScript = "var t = this.getAnnot(this.pageNum, '" + name + "'); t.popupOpen = false;";
field.Actions.OnEnter = new JavascriptAction(openScript);
field.Actions.OnExit = new JavascriptAction(closeScript);

/*Save document*/
doc.Save(TestSettings.GetOutputFile("36228.pdf"));

除了上述新功能外，本次更新还包含了近90个问题修复，所以说Aspose.Pdf for .NET 9.4.0是一个重要版本。相比之前的所有版本，我们称之为“更好的spose.Pdf for .NET API ” 。赶快下载最新试用版吧Aspose.Pdf for .NET 9.4.0.