Render PDF documents as HTML and image files Leave feedback

GroupDocs.Viewer for .NET allows you to render your PDF files in HTML, PNG, and JPEG formats. Use this library to implement a simple PDF viewer within your .NET application (web or desktop).

Create a Viewer class instance to get started with the GroupDocs.Viewer API. Pass a document you want to view to the class constructor. You can load the document from a file or stream. Call one of the Viewer.View method overloads to convert the document to HTML or image format. These methods allow you to render the entire document or specific pages.

View PDF files online View demos and examples on GitHub

GroupDocs.Viewer supports the following PDF and Page Layout file formats:

• Portable Document Format (.PDF)
• Microsoft XML Paper Specification (.XPS)
• Open XML Paper Specification (.OXPS)
• LaTeX Source Document (.TEX)

GroupDocs.Viewer can detect the document format automatically based on information in the file header.

Create an HtmlViewOptions class instance and pass it to the Viewer.View method to convert a PDF file to HTML. The HtmlViewOptions class properties allow you to control the conversion process. For instance, you can embed all external resources in the generated HTML file, minify the output file, and optimize it for printing. Refer to the following documentation section for details: Rendering to HTML.

To save all elements of an HTML page (including text, graphics, and stylesheets) into a single file, call the HtmlViewOptions.ForEmbeddedResources method and specify the output file name.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create an HTML file for each PDF page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    viewer.View(viewOptions);
}

The following image demonstrates the result:

If you want to store an HTML file and additional resource files (such as fonts, images, and stylesheets) separately, call the HtmlViewOptions.ForExternalResources method and pass the following parameters:

• The output file path format
• The path format for the folder with external resources
• The resource URL format

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create an HTML file for each PDF page.
    // Specify the HTML file names and location of external resources.
    // {0} and {1} are replaced with the current page number and resource name, respectively.
    var viewOptions = HtmlViewOptions.ForExternalResources("page_{0}.html", "page_{0}/resource_{0}_{1}", "page_{0}/resource_{0}_{1}");
    viewer.View(viewOptions);
}

The image below demonstrates the result. External resources are placed in a separate folder.

By default, PDF and EPUB documents are rendered to HTML with fixed layout to ensure that the output HTML looks the same as a source document. Rendering to fixed layout means that all the HTML elements are absolutely positioned to the container element. And container element has a fixed size so browser window resizing won’t have an effect on the position and size of elements in a document.

The following image demonstrates PDF document rendered HTML with fixed layout:

When rendering to HTML with fluid layout HTML document doesn’t have a fixed size. In case you resize a browser window the document content tries to fit into it. To create HTML with fluid layout set PdfOptions.FixedLayout property to false.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("Letter.pdf"))
{
    // Create an HTML file for each PDF page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    // Disable fixed layout.
    viewOptions.PdfOptions.FixedLayout = false;
    viewer.View(viewOptions);
}

Note

When rendering PDF and EPUB documents to HTML with a fluid layout all the graphic content such as images are ignored.

The following image demonstrates the result:

The HtmlViewOptions.PdfOptions.ImageQuality option allows you to specify the quality of images in the output HTML file. You can set this property to one of the following values:

• ImageQuality.Low — The image resolution is low (96 DPI), and the image size is small. Use this value to increase the conversion performance.
• ImageQuality.Medium — The image resolution is medium (192 DPI), and the image size is larger compared to the low quality images.
• ImageQuality.High — The image resolution is high (300 DPI), and the image size is big. Use of this value may decrease the conversion performance.

The following code snippet shows how to set the medium image quality when rendering a PDF document to HTML:

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create an HTML file for each document page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    // Set image quality to medium.
    viewOptions.PdfOptions.ImageQuality = ImageQuality.Medium;
    viewer.View(viewOptions);
}

GroupDocs.Viewer supports the HtmlViewOptions.PdfOptions.RenderTextAsImage option that allows you to render text as an image when you convert a PDF file to HTML. In this case, the layout of the output HTML file closely mirrors the layout of the source PDF document.

The following code snippet shows how to enable this option in code:

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create an HTML file for each document page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("text-as-image_{0}.html");
    // Enable rendering text as image.
    viewOptions.PdfOptions.RenderTextAsImage = true;
    viewer.View(viewOptions);
}

The image below illustrates the result. PDF content is exported to HTML as an image, so users cannot select or copy document text.

When you convert a PDF file to HTML, GroupDocs.Viewer creates an HTML document with a single layer (the z-index is not specified for document elements). This helps increase performance and reduce the output file size. If you convert a PDF document with multiple layers and want to improve the position of document elements in the output HTML file, activate the HtmlViewOptions.PdfOptions.EnableLayeredRendering property to render text and graphics in the HTML file according to their z-order in the source PDF document.

The following code snippet shows how to enable the multi-layer rendering:

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("sample.pdf"))
{
    // Create an HTML file for each document page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    // Enable the multi-layer rendering.
    viewOptions.PdfOptions.EnableLayeredRendering = true;
    viewer.View(viewOptions);
}

Create a PngViewOptions class instance and pass it to the Viewer.View method to convert a PDF file to PNG. Use the PngViewOptions.Height and PngViewOptions.Width properties to specify the output image size in pixels.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create a PNG image for each PDF page.
    // {0} is replaced with the current page number in the image name.
    var viewOptions = new PngViewOptions("output_{0}.png");
    // Set width and height.
    viewOptions.Width = 800;
    viewOptions.Height = 900;
    viewer.View(viewOptions);
}

The following image demonstrates the result:

Create a JpgViewOptions class instance and pass it to the Viewer.View method to convert a PDF file to JPEG. Use the JpgViewOptions.Height and JpgViewOptions.Width properties to specify the output image size in pixels.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create a JPEG image for each PDF page.
    // {0} is replaced with the current page number in the image name.
    var viewOptions = new JpgViewOptions("output_{0}.jpg");
    // Set width and height.
    viewOptions.Width = 800;
    viewOptions.Height = 900;
    viewer.View(viewOptions);
}

When you render PDF documents as images, GroupDocs.Viewer calculates the optimal image size to achieve better rendering quality. If you want the generated images to be the same size as pages in the source PDF document, enable the PdfOptions.RenderOriginalPageSize property for the PngViewOptions or JpgViewOptions class (depending on the output image format).

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create a PNG image for each PDF page.
    // {0} is replaced with the current page number in the image name.
    var viewOptions = new PngViewOptions("output_{0}.png");
    // Preserve the size of document pages.
    viewOptions.PdfOptions.RenderOriginalPageSize = true;
    viewer.View(viewOptions);
}

To adjust the display of outline fonts when you convert PDF documents to PNG or JPEG, activate the PdfOptions.EnableFontHinting option, as shown below:

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    // Create a PNG image for each PDF page.
    // {0} is replaced with the current page number in the image name.
    var viewOptions = new PngViewOptions("output_{0}.png");
    //Enable font hinting
    viewOptions.PdfOptions.EnableFontHinting = true;
    viewer.View(viewOptions);
}

Refer to the following article for more information on font hinting: Font hinting.

When you render PDF files in other formats, GroupDocs.Viewer groups individual characters into words to improve rendering performance. If your document contains hieroglyphic or special symbols, you may need to disable character grouping to generate a more precise layout. To do this, use the PdfOptions.DisableCharsGrouping option, as shown below:

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("sample.pdf"))
{
    // Create an HTML file for each document page.
    // {0} is replaced with the current page number in the file name.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    // Disable character grouping
    viewOptions.PdfOptions.DisableCharsGrouping = true;
    viewer.View(viewOptions);
}

Enable the ViewOptions.RenderComments option for a target view to display textual annotations (such as text comments, sticky notes, text boxes and callouts) in the output HTML, PNG, or JPEG files.

The code example below renders a PDF file with text comments as an image.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
// ...

using (var viewer = new Viewer("resume_commented.pdf"))
{
    // Create a PNG image for each PDF page.
    // {0} is replaced with the current page number in the image name.
    var viewOptions = new PngViewOptions("output_{0}.png");
    // Enable comments rendering.
    viewOptions.RenderComments = true;
    viewer.View(viewOptions);
}

The following image illustrates the result:

Follow the steps below to obtain information about a PDF file (the number of pages, page size, and printing permissions):

1. Create a ViewInfoOptions instance for a specific view.
2. Call the Viewer.GetViewInfo method, pass the ViewInfoOptions instance to this method as a parameter, and cast the returned object to the PdfViewInfo type.
3. Use the PdfViewInfo class properties to retrieve document-specific information.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
using GroupDocs.Viewer.Results;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    var viewInfoOptions = ViewInfoOptions.ForHtmlView();
    var viewInfo = viewer.GetViewInfo(viewInfoOptions) as PdfViewInfo;

    // Display information about the PDF document.
    Console.WriteLine($"File type: {viewInfo.FileType}");
    Console.WriteLine($"The number of pages: {viewInfo.Pages.Count}");
    Console.WriteLine($"Is printing allowed: {viewInfo.PrintingAllowed}");
    
    // Display information about all document pages.
    Console.WriteLine("Page information:");
    foreach (Page page in viewInfo.Pages)
    {
        // The Page.ToString method is overriden to display the following page information: 
        // "Page {Number} ({visibility}) {Width}x{Height}px with {Lines.Count} line(s)."
        Console.WriteLine(page);
    }
}

The following image shows a sample console output:

Set the ViewInfoOptions.ExtractText property to true to enable PDF text extraction. Use the PdfViewInfo.Pages property to obtain the list of all document pages, and iterate through the collection of lines on each page (Page.Lines) to retrieve text for each line.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;
using GroupDocs.Viewer.Results;
// ...

using (var viewer = new Viewer("resume.pdf"))
{
    var viewInfoOptions = ViewInfoOptions.ForHtmlView();
    viewInfoOptions.ExtractText = true;
    var viewInfo = viewer.GetViewInfo(viewInfoOptions) as PdfViewInfo;
    
    // Retrieve text from the PDF file.
    Console.WriteLine("Extracted document text:");
    foreach (Page page in viewInfo.Pages)
        foreach (Line line in page.Lines)
        {
            Console.WriteLine(line.Value);
        }
}

If an XPS or OXPS file contains a font that cannot be embedded due to licensing restrictions, GroupDocs.Viewer throws an exception at runtime. If you have a license for this font, enable the PdfOptions.DisableFontLicenseVerifications option to skip font license verification.

using (Viewer viewer = new Viewer("resume.oxps"))
{
    HtmlViewOptions viewOptions = HtmlViewOptions.ForEmbeddedResources();
    options.PdfOptions.DisableFontLicenseVerifications = true;
    viewer.View(viewOptions);
}

By default, when rendering to the PDF and Page Layout file formats, all images are combined into a single PNG file, which serves as the background for the output HTML document.

The PdfOptions.WrapImagesInSvg option allows you to wrap each image in the output HTML document with an SVG tag to improve output quality.

This option is available when rendering PDF and Page Layout file formats to HTML with embedded or external resources.

using (Viewer viewer = new Viewer("resume.pdf"))
{
    HtmlViewOptions viewOptions = HtmlViewOptions.ForEmbeddedResources();
    viewOptions.PdfOptions.WrapImagesInSvg = true;

    viewer.View(viewOptions);
}

The following image shows the rendering resume.pdf with the disabled (left) and enabled (right) WrapImagesInSvg option:

When rendering PDF files with protection against copying text and images to HTML, GroupDocs.Viewer adds an inert HTML attribute to the HTML <body> tag.

Use PdfOptions.DisableCopyProtection to turn off copy protection. When DisableCopyProtection is set to true, the inert HTML attribute won’t be added to the HTML <body> tag in any case.

Note

This option was added in GroupDocs.Viewer for .NET 24.4. Previous versions of GroupDocs.Viewer for .NET ignores PDF copy protection and does not add inert HTML attribute to HTML <body> tag.

This option is supported when rendering PDF files to HTML with embedded or external resources.

using (Viewer viewer = new Viewer("protected-resume.pdf"))
{
    HtmlViewOptions viewOptions = HtmlViewOptions.ForEmbeddedResources();
    viewOptions.PdfOptions.DisableCopyProtection = true;

    viewer.View(viewOptions);
}

The following image shows the rendering of protected-resume.pdf with copy protection on the left and with with DisableCopyProtection option set to true on the right: