Question

I have a button on a page that creates a PDF of the page. I would like to hide the button for the pdf then show it after the pdf is created. I tried the following in codebehind and it does not hide the button.

Private Sub PdfPageButton_ServerClick(sender As Object, e As System.EventArgs) Handles PdfPageButton.ServerClick
    PdfPageButton.Visible = False
    ConvertURLToPDF()
    PdfPageButton.Visible = True
End Sub

Private Sub ConvertURLToPDF()
    Dim urlToConvert As String = HttpContext.Current.Request.Url.AbsoluteUri

    'more code here not displayed...   

    ' Performs the conversion and get the pdf document bytes that you can further 
    ' save to a file or send as a browser response
    Dim pdfBytes As Byte() = pdfConverter.GetPdfBytesFromUrl(urlToConvert)

    ' send the PDF document as a response to the browser for download
    Dim Response As System.Web.HttpResponse = System.Web.HttpContext.Current.Response
    Response.Clear()
    Response.AddHeader("Content-Type", "binary/octet-stream")
    Response.AddHeader("Content-Disposition", "attachment; filename=ConversionResult.pdf; size=" & pdfBytes.Length.ToString())
    Response.Flush()
    Response.BinaryWrite(pdfBytes)
    Response.Flush()
    Response.End()
End Sub

However I use [@media print] in css to not display my print button. to bad it doesn’t work in other ways

Answer 1

The reason it doesn’t hide the button is because the page doesn’t get rendered again before this line:

PdfPageButton.Visible = True

If it were WinForms, your approach would work but on the web you need to do it a bit differently.

You could hide the button by simply setting a CSS style of display:none in the button’s onclick() event:

<input type="button" id="pdfBtn" onclick="this.style.display = 'none';" />

but to show it again when the PDF has been generated, you’d either need to refresh the page in its entirety (i.e. a postback), or you could wire up an event listener if you wanted to use AJAX.

EDIT: Given the extra info that the PDF is of the page itself, could you perhaps add a querystring parameter to the URL, e.g.

mysite/mypage.aspx?isPDF=1

Then, in your PageLoad(), add:

if(Request.QueryString["isPDF"] == "1")
{
    PdfButton.Visible == false;
} 

so that the button doesn’t exist when isPDF is set to ‘1’ (or whatever you choose).

Then, pass that URL with the extra param to the ConvertURLToPDF() method?