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    5. GroupDocs.Viewer for .NET
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    7. Document rendering basics
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    9. Render web documents

    Render web documents as PDF, PNG, and JPEG files

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    GroupDocs.Viewer for .NET allows you to render web documents as PDF, PNG, and JPEG files. Use this library to view web files within your .NET application.

    To start using the GroupDocs.Viewer API, create a Viewer class instance. Pass a web 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 PDF or image format. These methods allow you to render the entire document or specific pages.

    View web files online View demos and examples on GitHub

    Supported web file formats

    GroupDocs.Viewer supports the following web file formats:

    GroupDocs.Viewer can detect the document format automatically by analyzing file contents.

    Render web documents as PDF

    Create a PdfViewOptions class instance and pass it to the Viewer.View method to convert a web file to PDF. The PdfViewOptions class properties allow you to control the conversion process. For instance, you can protect the output PDF file, reorder its pages, and specify the quality of document images. Refer to the following documentation section for details: Rendering to PDF.

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

using (var viewer = new Viewer("groupdocs-documentation.mhtml"))
{
    // Create a PDF file for the document.
    // Specify the PDF file name.
    var viewOptions = new PdfViewOptions("output.pdf");
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("groupdocs-documentation.mhtml")
            ' Create a PDF file for the document.
            ' Specify the PDF file name.
            Dim viewOptions = New PdfViewOptions("output.pdf")
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    The following image demonstrates the result:

    Render a web file to PDF

    Render web documents as PNG

    Create a PngViewOptions class instance and pass it to the Viewer.View method to convert a web 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("groupdocs-documentation.mhtml"))
{
    // Convert the web file to PNG.
    // {0} is replaced with the page numbers in the output image names.
    var viewOptions = new PngViewOptions("output_{0}.png");
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("groupdocs-documentation.mhtml")
            ' Convert the web file to PNG.
            ' {0} is replaced with the page numbers in the output image names.
            Dim viewOptions = New PngViewOptions("output_{0}.png")
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    The following image demonstrates the result:

    Render a web file to PNG

    Render web documents as JPEG

    Create a JpgViewOptions class instance and pass it to the Viewer.View method to convert a web 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("groupdocs-documentation.mhtml"))
{
    // Convert the web file to JPEG.
    // {0} is replaced with the page numbers in the output image names.
    var viewOptions = new JpgViewOptions("output_{0}.jpg");
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("groupdocs-documentation.mhtml")
            ' Convert the web file to JPEG.
            ' {0} is replaced with the page numbers in the output image names.
            Dim viewOptions = New JpgViewOptions("output_{0}.jpg")
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    Convert CHM files to HTML

    CHM is a Microsoft proprietary online help format that is often used for software documentation. With GroupDocs.Viewer, you can convert a CHM file to HTML to display this file in a web browser. To do this, create an HtmlViewOptions class instance and pass it to the Viewer.View method. 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.

    Create an HTML file with embedded resources

    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("sample.chm"))
{
    // Convert the CHM file to HTML.
    // {0} is replaced with the page numbers in the output file names.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("chm_result_{0}.html");
    // Enable the following option to display all CHM content on a single HTML page.
    // options.RenderToSinglePage = true;
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("sample.chm")
            ' Convert the CHM file to HTML.
            ' {0} is replaced with the page numbers in the output file names.
            Dim viewOptions = HtmlViewOptions.ForEmbeddedResources("chm_result_{0}.html")
            ' Enable the following option to display all CHM content on a single HTML page.
            ' options.RenderToSinglePage = true;
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    The following image demonstrates the result:

    Render a web file to HTML

    Create an HTML file with external resources

    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("sample.chm"))
{
    // Convert the CHM file to HTML.
    // Specify the output 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);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("sample.chm")
            ' Convert the CHM file to HTML.
            ' Specify the output file names and location of external resources.
            ' {0} and {1} are replaced with the current page number and resource name, respectively.
            Dim viewOptions = HtmlViewOptions.ForExternalResources("page_{0}.html", "page_{0}/resource_{0}_{1}", "page_{0}/resource_{0}_{1}")
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    Specify rendering options

    GroupDocs.Viewer supports the WebDocumentOptions class that allows you to specify different options for rendering web files. To access these options, use the WebDocumentOptions property for one of the following classes (depending on the output file format):

    Adjust page margins

    Use the following properties to specify the size of page margins in the output files when you convert your web documents to HTML, PDF, and image formats:

    • WebDocumentOptions.TopMargin—Specifies the distance (in points) between the top edge of the page and the top boundary of the body text. The default value is 72 points.
    • WebDocumentOptions.BottomMargin—Specifies the distance (in points) between the bottom edge of the page and the bottom boundary of the body text. The default value is 72 points.
    • WebDocumentOptions.LeftMargin—Specifies the distance (in points) between the left edge of the page and the left boundary of the body text. The default value is 5 points.
    • WebDocumentOptions.RightMargin—Specifies the distance (in points) between the right edge of the page and the right boundary of the body text. The default value is 5 points.

    The example below converts a web document to PDF and specifies page margins for the output file.

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

using (var viewer = new Viewer("groupdocs-documentation.mhtml"))
{
    // Convert the document to PDF.
    var viewOptions = new PdfViewOptions("output.pdf");
    // Specify the size of page margins in points.
    viewOptions.WebDocumentOptions.LeftMargin = 40;
    viewOptions.WebDocumentOptions.RightMargin = 40;
    viewOptions.WebDocumentOptions.TopMargin = 40;
    viewOptions.WebDocumentOptions.BottomMargin = 40;
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("groupdocs-documentation.mhtml")
            ' Convert the document to PDF.
            Dim viewOptions = New PdfViewOptions("output.pdf")
            ' Specify the size of page margins in points.
            viewOptions.WebDocumentOptions.LeftMargin = 40
            viewOptions.WebDocumentOptions.RightMargin = 40
            viewOptions.WebDocumentOptions.TopMargin = 40
            viewOptions.WebDocumentOptions.BottomMargin = 40
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

    Set the output page size

    GroupDocs.Viewer allows you to specify page size for the output file when you convert your web document to another format. Assign a PageSize enumeration member to the WebDocumentOptions.PageSize property to select one of the predefined page sizes (Letter, Ledger, A0, A1, A2, A3, or A4).

    The following example specifies page size for the output PDF file:

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

using (var viewer = new Viewer("groupdocs-documentation.mhtml"))
{
    // Convert the document to PDF.
    var viewOptions = new PdfViewOptions("output.pdf");
    // Specify the page size.
    viewOptions.WebDocumentOptions.PageSize = PageSize.A3;
    viewer.View(viewOptions);
}

    Imports GroupDocs.Viewer
Imports GroupDocs.Viewer.Options
' ...

Module Program
    Sub Main(args As String())
        Using viewer = New Viewer("groupdocs-documentation.mhtml")
            ' Convert the document to PDF.
            Dim viewOptions = New PdfViewOptions("output.pdf")
            ' Specify the page size.
            viewOptions.WebDocumentOptions.PageSize = PageSize.A3
            viewer.View(viewOptions)
        End Using
    End Sub
End Module

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