EVO HTML to PDF Converter

Automatically Resize the 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 HTML to PDF converter object as a class member to make it accessible in the headerHtml_NavigationCompletedEvent handler
// where the header height will be automatically adjusted
private HtmlToPdfConverter htmlToPdfConverter;

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

protected void convertToPdfButton_Click(object sender, EventArgs e)
{
    // Create a HTML to PDF converter object with default settings
    htmlToPdfConverter = new HtmlToPdfConverter();

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

    // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2;

    // Enable header in the generated PDF document
    htmlToPdfConverter.PdfDocumentOptions.ShowHeader = true;

    string headerHtmlUrl = Server.MapPath("~/DemoAppFiles/Input/HTML_Files/Header_HTML.html");
    Document documentObject = null;
    try
    {
        if (autoResizeHeaderRadioButton.Checked)
        {
            // Create a HTML element to be added in header
            HtmlToPdfElement headerHtml = new HtmlToPdfElement(headerHtmlUrl);

            // Install a handler where to set the automatically calculated header 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
            htmlToPdfConverter.PdfHeaderOptions.AddElement(headerHtml);

            // Call the converter to produce a Document object
            documentObject = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text);

            // Uninstall the handler
            headerHtml.NavigationCompletedEvent -= new NavigationCompletedDelegate(headerHtml_NavigationCompletedEvent);

            // Draw a line at the header bottom
            if (drawHeaderLine)
            {
                float headerWidth = documentObject.Header.Width;
                float headerHeight = documentObject.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
                documentObject.Header.AddElement(headerLine);
            }

            // Save the PDF document in a memory buffer
            byte[] outPdfBuffer = documentObject.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();
        }
        else
        {
            // Create a HTML to PDF element to be added in header
            HtmlToPdfElement headerHtml = new HtmlToPdfElement(headerHtmlUrl);

            // Set a fixed header height in points
            htmlToPdfConverter.PdfHeaderOptions.HeaderHeight = float.Parse(headerHeightTextBox.Text);

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

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

            // Draw a line at the header bottom
            if (drawHeaderLine)
            {
                // Calculate the header width based on PDF page size and margins
                float headerWidth = htmlToPdfConverter.PdfDocumentOptions.PdfPageSize.Width -
                            htmlToPdfConverter.PdfDocumentOptions.LeftMargin - htmlToPdfConverter.PdfDocumentOptions.RightMargin;

                // Calculate header height
                float headerHeight = htmlToPdfConverter.PdfHeaderOptions.HeaderHeight;

                // 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
                htmlToPdfConverter.PdfHeaderOptions.AddElement(headerLine);
            }

            // Convert the HTML page to a PDF document in a memory buffer
            byte[] outPdfBuffer = htmlToPdfConverter.ConvertUrl(urlTextBox.Text);

            // 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
        if (documentObject != null)
            documentObject.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;

    // Calculate the header width from coverter settings
    float headerWidth = htmlToPdfConverter.PdfDocumentOptions.PdfPageSize.Width - htmlToPdfConverter.PdfDocumentOptions.LeftMargin -
                htmlToPdfConverter.PdfDocumentOptions.RightMargin;

    // 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 < htmlToPdfConverter.PdfDocumentOptions.PdfPageSize.Height - htmlToPdfConverter.PdfDocumentOptions.TopMargin -
                htmlToPdfConverter.PdfDocumentOptions.BottomMargin))
    {
        throw new Exception("The header height cannot be bigger than PDF page height");
    }

    // Set the calculated header height
    htmlToPdfConverter.PdfDocumentOptions.DocumentObject.Header.Height = headerHeight;
}