EVO HTML to PDF Converter

Auto Resize Header and Footer

EVO HTML to PDF Converter for .NET Documentation

EVO HTML to PDF Converter allows you to automatically resize the header and footer to adapt to HTML content being rendered. The resizing is done in the handler of the HtmlToPdfElementNavigationCompletedEvent event of the EvoPdfHtmlToPdfElement object added in header or footer.

Code Sample - Automatically Resize the Header and Footer
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// Define the PDF Document object as a class member to make it accessible in the headerHtml_NavigationCompletedEvent handler
// where the header height will be automatically adjusted
private Document pdfDocument;

// Indicates if a line should be drawn at the botom of the header
private bool drawHeaderLine = true;

protected void createPdfButton_Click(object sender, EventArgs e)
{
    // Create a PDF document
    pdfDocument = new Document();

    // Set license key received after purchase to use the converter in licensed mode
    // Leave it not set to use the converter in demo mode
    pdfDocument.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

    // Add a PDF page to PDF document
    PdfPage pdfPage = pdfDocument.AddPage();

    string headerHtmlUrl = Server.MapPath("~/DemoAppFiles/Input/HTML_Files/Header_HTML.html");
    try
    {
        // Add the header to PDF document
        if (autoResizeHeaderRadioButton.Checked)
        {
            // Create the document header with a default height
            // It will be automatically resized in headerHtml_NavigationCompletedEvent handler
            pdfDocument.AddHeaderTemplate(50);

            // Create a HTML element to be added in header
            HtmlToPdfElement headerHtml = new HtmlToPdfElement(headerHtmlUrl);

            // Install a handler where to create the document header based on HTML element height
            headerHtml.NavigationCompletedEvent += new NavigationCompletedDelegate(headerHtml_NavigationCompletedEvent);

            // Add the HTML element to header
            // When the element is rendered in header by converter, the headerHtml_NavigationCompletedEvent handler 
            // will be invoked and the header height will be automatically calculated
            pdfDocument.Header.AddElement(headerHtml);

            // Uninstall the handler
            headerHtml.NavigationCompletedEvent += new NavigationCompletedDelegate(headerHtml_NavigationCompletedEvent);
        }
        else
        {
            // Create the document header with a fixed height
            pdfDocument.AddHeaderTemplate(float.Parse(headerHeightTextBox.Text));

            // Create a HTML to PDF element to be added in header
            HtmlToPdfElement headerHtml = new HtmlToPdfElement(headerHtmlUrl);

            // Set the HTML element to fit the container height
            headerHtml.FitHeight = true;

            // Add HTML element to fit the fixed header height
            pdfDocument.Header.AddElement(headerHtml);

        }

        // Draw a line at the header bottom
        if (drawHeaderLine)
        {
            float headerWidth = pdfDocument.Header.Width;
            float headerHeight = pdfDocument.Header.Height;

            // Create a line element for the bottom of the header
            LineElement headerLine = new LineElement(0, headerHeight - 1, headerWidth, headerHeight - 1);

            // Set line color
            headerLine.ForeColor = Color.Gray;

            // Add line element to the bottom of the header
            pdfDocument.Header.AddElement(headerLine);
        }

        // Create a HTML to PDF element to add to document
        HtmlToPdfElement htmlToPdfElement = new HtmlToPdfElement(urlTextBox.Text);

        // Optionally set a delay before conversion to allow asynchonous scripts to finish
        htmlToPdfElement.ConversionDelay = 2;

        // Add the HTML to PDF element to document
        pdfPage.AddElement(htmlToPdfElement);

        // Save the PDF document in a memory buffer
        byte[] outPdfBuffer = pdfDocument.Save();

        // Send the PDF as response to browser

        // Set response content type
        Response.AddHeader("Content-Type", "application/pdf");

        // Instruct the browser to open the PDF file as an attachment or inline
        Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Auto_Resize_Header_Footer.pdf; size={0}", outPdfBuffer.Length.ToString()));

        // Write the PDF document buffer to HTTP response
        Response.BinaryWrite(outPdfBuffer);

        // End the HTTP response and stop the current page processing
        Response.End();
    }
    finally
    {
        // Close the PDF document
        pdfDocument.Close();
    }
}

/// <summary>
/// This handler is called after the navigation to header HTML completed. The document header is resized in this event handler
/// </summary>
/// <param name="eventParams">The event parameter containing the HTML content size in pixels and points</param>
void headerHtml_NavigationCompletedEvent(NavigationCompletedParams eventParams)
{
    // Get the header HTML width and height from event parameters
    float headerHtmlWidth = eventParams.HtmlContentWidthPt;
    float headerHtmlHeight = eventParams.HtmlContentHeightPt;

    // Get the header width
    float headerWidth = pdfDocument.Header.Width;

    // Calculate a resize factor to fit the header width
    float resizeFactor = 1;
    if (headerHtmlWidth > headerWidth)
        resizeFactor = headerWidth / headerHtmlWidth;

    // Calculate the header height to preserve the HTML aspect ratio
    float headerHeight = headerHtmlHeight * resizeFactor;

    if (!(headerHeight < pdfDocument.Pages[0].PageSize.Height - pdfDocument.Pages[0].Margins.Top -
                pdfDocument.Pages[0].Margins.Bottom))
    {
        throw new Exception("The header height cannot be bigger than PDF page height");
    }

    // Set the calculated header height
    pdfDocument.Header.Height = headerHeight;
}