Convert PowerPoint to HTML in C# .NET

Overview

This article explains how to convert PowerPoint Presentation in HTML format using C#. It covers the following topics.

C# PowerPoint to HTML

For C# sample code to convert PowerPoint to HTML, please see the section below i.e. Convert PowerPoint to HTML. The code can load number of formats like PPT, PPTX and ODP in Presentation object and save it to HTML format.

About PowerPoint to HTML Conversion

Using Aspose.Slides for .NET, applications and developers can convert a PowerPoint presentation to HTML: PPTX to HTML or PPT to HTML.

Aspose.Slides provides many options (mostly from the HtmlOptions class) that define the PowerPoint to HTML conversion process:

  • Convert an entire PowerPoint presentation to HTML.
  • Convert a specific slide in a PowerPoint presentation to HTML.
  • Convert presentation media (images, videos, etc.) to HTML.
  • Convert a PowerPoint presentation to responsive HTML.
  • Convert a PowerPoint presentation to HTML with speaker notes included or excluded.
  • Convert a PowerPoint presentation to HTML with comments included or excluded.
  • Convert a PowerPoint presentation to HTML with original or embedded fonts.
  • Convert a PowerPoint presentation to HTML while using the new CSS style.

Convert PowerPoint to HTML

Using Aspose.Slides, you can convert an entire PowerPoint presentation to HTML this way:

  1. Create an instance of the Presentation class.
  2. Use the Save method to save the object as an HTML file.

This code shows you how to convert a PowerPoint to HTML in C#:

// Instantiates a presentation object that represents a presentation file e.g. PPT, PPTX, ODP etc.
using (Presentation presentation = new Presentation("Convert_HTML.pptx"))
{
    HtmlOptions htmlOpt = new HtmlOptions();
    
    INotesCommentsLayoutingOptions options = htmlOpt.NotesCommentsLayouting;
    options.NotesPosition = NotesPositions.BottomFull;
    
    htmlOpt.HtmlFormatter = HtmlFormatter.CreateDocumentFormatter("", false);

    // Saves the presentation to HTML
    presentation.Save("ConvertWholePresentationToHTML_out.html", SaveFormat.Html, htmlOpt);
}

Convert PowerPoint to Responsive HTML

Aspose.Slides provides the ResponsiveHtmlController class that allows you to generate responsive HTML files. This code shows you how to convert a PowerPoint presentation to responsive HTML in C#:

// Instantiates a Presentation object that represents a presentation file
using (Presentation presentation = new Presentation("Convert_HTML.pptx"))
{
    ResponsiveHtmlController controller = new ResponsiveHtmlController();
    HtmlOptions htmlOptions = new HtmlOptions { HtmlFormatter = HtmlFormatter.CreateCustomFormatter(controller) };

    // Saves the presentation to HTML
    presentation.Save("ConvertPresentationToResponsiveHTML_out.html", SaveFormat.Html, htmlOptions);
}

Convert PowerPoint to HTML with Notes

This code shows you how to convert a PowerPoint to HTML with notes in C#:

using (Presentation pres = new Presentation("Presentation.pptx"))
{
    HtmlOptions opt = new HtmlOptions();

    INotesCommentsLayoutingOptions options = opt.NotesCommentsLayouting;
    options.NotesPosition = NotesPositions.BottomFull;

    // Saves notes pages
    pres.Save("Output.html", SaveFormat.Html, opt);
}

Convert PowerPoint to HTML with Original Fonts

Aspose.Slides provides the EmbedAllFontsHtmlController class that allows you to embed all the fonts in a presentation while converting the presentation to HTML.

To prevent certain fonts from being embedded, you can pass an array of font names to a parameterized constructor from the EmbedAllFontsHtmlController class. Popular fonts, such as Calibri or Arial, when used in a presentation, do not have to be embedded because most systems already contain such fonts. When those fonts are embedded, the resulting HTML document becomes unnecessarily large.

The EmbedAllFontsHtmlController class supports inheritance and provides the WriteFont method, which is meant to be overwritten.

using (Presentation pres = new Presentation("input.pptx"))
{
    // Excludes default presentation fonts
    string[] fontNameExcludeList = { "Calibri", "Arial" };

    EmbedAllFontsHtmlController embedFontsController = new EmbedAllFontsHtmlController(fontNameExcludeList);

    HtmlOptions htmlOptionsEmbed = new HtmlOptions
    {
        HtmlFormatter = HtmlFormatter.CreateCustomFormatter(embedFontsController)
    };

    pres.Save("input-PFDinDisplayPro-Regular-installed.html", SaveFormat.Html, htmlOptionsEmbed);
}

Convert PowerPoint to HTML with High-quality Images

By default, when you convert PowerPoint to HTML, Aspose.Slides outputs small HTML with images at 72 DPI and deleted cropped areas. To obtain HTML files with higher quality images, you have to set the PicturesCompression property (from the HtmlOptions class) to 96 (i.e., PicturesCompression.Dpi96) or higher values.

This C# code shows you how to convert a PowerPoint presentation to HTML while obtaining high quality images at 150 DPI (i.e. PicturesCompression.Dpi150):

Presentation pres = new Presentation("InputDoc.pptx");
HtmlOptions htmlOpts = new HtmlOptions
{
    PicturesCompression = PicturesCompression.Dpi150
};
pres.Save("OutputDoc-dpi150.html", Aspose.Slides.Export.SaveFormat.Html, htmlOpts);

This code in C# shows you how to output HTML with full quality images:

Presentation pres = new Presentation("InputDoc.pptx");
HtmlOptions htmlOpts = new HtmlOptions
{
    DeletePicturesCroppedAreas = false
};
pres.Save("Outputdoc-noCrop.html", Aspose.Slides.Export.SaveFormat.Html, htmlOpts);

Convert Slide to HTML

To convert a specific slide in a PowerPoint to HTML, you have to instantiate the same Presentation class (used to convert entire presentations to HTML) and then use the Save method to save the file as HTML. The HtmlOptions class can be used to specify additional conversion options:

This C# code shows you how to convert a slide in a PowerPoint presentation to HTML:

public static void Run()
{
    using (Presentation presentation = new Presentation("Individual-Slide.pptx"))
    {
        HtmlOptions htmlOptions = new HtmlOptions();

        INotesCommentsLayoutingOptions options = htmlOptions.NotesCommentsLayouting;
        options.NotesPosition = NotesPositions.BottomFull;

        htmlOptions.HtmlFormatter = HtmlFormatter.CreateCustomFormatter(new CustomFormattingController());

        // Saves File              
        for (int i = 0; i < presentation.Slides.Count; i++)
            presentation.Save("Individual Slide" + (i + 1) + "_out.html", new[] { i + 1 }, SaveFormat.Html, htmlOptions);
    }
}

public class CustomFormattingController : IHtmlFormattingController
{
    void IHtmlFormattingController.WriteDocumentStart(IHtmlGenerator generator, IPresentation presentation)
    {}

    void IHtmlFormattingController.WriteDocumentEnd(IHtmlGenerator generator, IPresentation presentation)
    {}

    void IHtmlFormattingController.WriteSlideStart(IHtmlGenerator generator, ISlide slide)
    {
        generator.AddHtml(string.Format(SlideHeader, generator.SlideIndex + 1));
    }

    void IHtmlFormattingController.WriteSlideEnd(IHtmlGenerator generator, ISlide slide)
    {
        generator.AddHtml(SlideFooter);
    }

    void IHtmlFormattingController.WriteShapeStart(IHtmlGenerator generator, IShape shape)
    {}

    void IHtmlFormattingController.WriteShapeEnd(IHtmlGenerator generator, IShape shape)
    {}

    private const string SlideHeader = "<div class=\"slide\" name=\"slide\" id=\"slide{0}\">";
    private const string SlideFooter = "</div>";
}

Save CSS and Images When Exporting To HTML

Using new CSS style files, you can easily change the style of the HTML file resulting from the PowerPoint to HTML conversion process.

The C# code in this example shows you how to use overridable methods to create a custom HTML document with a link to a CSS file:

using (Presentation pres = new Presentation("pres.pptx"))
{
	CustomHeaderAndFontsController htmlController = new CustomHeaderAndFontsController("styles.css");
	HtmlOptions options = new HtmlOptions
	{
		HtmlFormatter = HtmlFormatter.CreateCustomFormatter(htmlController),
	};
	pres.Save("pres.html", SaveFormat.Html, options);
}

public class CustomHeaderAndFontsController : EmbedAllFontsHtmlController
{
    // Custom header template
    const string Header = "<!DOCTYPE html>\n" +
                            "<html>\n" +
                            "<head>\n" +
                            "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\n" +
                            "<meta http-equiv=\"X-UA-Compatible\" content=\"IE=9\">\n" +
                            "<link rel=\"stylesheet\" type=\"text/css\" href=\"{0}\">\n" +
                            "</head>";


    private readonly string m_cssFileName;

    public CustomHeaderAndFontsController(string cssFileName)
    {
        m_cssFileName = cssFileName;
    }

    public override void WriteDocumentStart(IHtmlGenerator generator, IPresentation presentation)
    {
        generator.AddHtml(string.Format(Header, m_cssFileName));
        WriteAllFonts(generator, presentation);
    }

    public override void WriteAllFonts(IHtmlGenerator generator, IPresentation presentation)
    {
        generator.AddHtml("<!-- Embedded fonts -->");
        base.WriteAllFonts(generator, presentation);
    }
}

If you do not want to embed fonts (to avoid increasing the size of the resulting HTML), you can link all fonts by implementing your own LinkAllFontsHtmlController version.

This C# code shows you how to convert a PowerPoint to HTML while linking all fonts and excluding “Calibri” and “Arial” (since they already exist in the system):

using (Presentation pres = new Presentation("pres.pptx"))
{
    //Excludes default presentation fonts
    string[] fontNameExcludeList = { "Calibri", "Arial" };

    Paragraph para = new Paragraph();
    ITextFrame txt;

    LinkAllFontsHtmlController linkcont = new LinkAllFontsHtmlController(fontNameExcludeList, @"C:\Windows\Fonts\");;

    HtmlOptions htmlOptionsEmbed = new HtmlOptions
    {
        HtmlFormatter = HtmlFormatter.CreateCustomFormatter(linkcont)
    };

    pres.Save("pres.html", SaveFormat.Html, htmlOptionsEmbed);
}

This C# code shows you how LinkAllFontsHtmlController is implemented:

public class LinkAllFontsHtmlController : EmbedAllFontsHtmlController
{
    private readonly string m_basePath;

    public LinkAllFontsHtmlController(string[] fontNameExcludeList, string basePath) : base(fontNameExcludeList)
    {
        m_basePath = basePath;
    }

    public override void WriteFont
    (
            IHtmlGenerator generator,
            IFontData originalFont,
            IFontData substitutedFont,
            string fontStyle,
            string fontWeight,
            byte[] fontData)
    {
        try
        {
            string fontName = substitutedFont == null ? originalFont.FontName : substitutedFont.FontName;
            string path = fontName + ".woff"; //Some path sanitaze may be needed

            File.WriteAllBytes(Path.Combine(m_basePath, path), fontData);
            
            generator.AddHtml("<style>");
            generator.AddHtml("@font-face { ");
            generator.AddHtml("font-family: '" + fontName + "'; ");
            generator.AddHtml("src: url('" + path + "')");

            generator.AddHtml(" }");
            generator.AddHtml("</style>");
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

Convert PowerPoint to Responsive HTML

This C# code shows you how to convert a PowerPoint presentation to responsive HTML:

Presentation presentation = new Presentation("SomePresentation.pptx");
HtmlOptions saveOptions = new HtmlOptions();
saveOptions.SvgResponsiveLayout = true;
presentation.Save("SomePresentation-out.html", SaveFormat.Html, saveOptions);

Export Media Files to HTML

Using Aspose.Slides for .NET, you can export media files this way:

  1. Create an instance of the Presentation class.
  2. Get a reference to the slide.
  3. Add a video to the slide.
  4. Write the presentation as a HTML file.

This C# code shows you how to add a video to the presentation and then save it as HTML:

// Loads a presentation
using (Presentation pres = new Presentation())
{
    string path = "C:/out/";
    const string fileName = "ExportMediaFiles_out.html";
    const string baseUri = "http://www.example.com/";

    using (FileStream fileStream = new FileStream("my_video.avi", FileMode.Open, FileAccess.Read))
    {
        IVideo video = pres.Videos.AddVideo(fileStream, LoadingStreamBehavior.ReadStreamAndRelease);
        
        ISlide slide = pres.Slides[0];
        slide.Shapes.AddVideoFrame(10, 10, 100, 100, video);
    }
        
    VideoPlayerHtmlController controller = new VideoPlayerHtmlController(path, fileName, baseUri);

    // Sets HTML options
    HtmlOptions htmlOptions = new HtmlOptions(controller);
    SVGOptions svgOptions = new SVGOptions(controller);

    htmlOptions.HtmlFormatter = HtmlFormatter.CreateCustomFormatter(controller);
    htmlOptions.SlideImageFormat = SlideImageFormat.Svg(svgOptions);

    // Saves the file
    pres.Save(Path.Combine(path, fileName), SaveFormat.Html, htmlOptions);
}
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