Save Canvas Control Image to a PDF using JavaScript, WebMethod andiTextSharp

Qamar, Mo 106 Reputation points
2022-03-02T22:11:09.627+00:00

I have a Canvas control (id=cnv) along with a few Input (type=text) controls in an aspx page and an input button control. When button is clicked, it calls StartSign() which calls SignResponse(event) and that calls the function SetValues(objResponse, imageWidth, imageHeight) to render signature on the “cnv” control.
The function SetValues(objResponse, imageWidth, imageHeight) sends all Session Variables (FName, LName) as a delimited string “name” to code behind in a WebMethod which saves data to a pdf file using iTextSharp.

BUT, I do not know how to pass and save the image (signature) which is created in the function SetValues().

Please help!
179451-codeforsession.txt

ASP.NET
ASP.NET
A set of technologies in the .NET Framework for building web applications and XML web services.
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Accepted answer
  1. Lan Huang-MSFT 26,526 Reputation points Microsoft Vendor
    2022-03-03T06:34:15.297+00:00

    Hi @Qamar, Mo ,
    From your description, I suggest that you can use jqu ery toDataURL to convert the canvas to image/png format first.
    We can then use ajax to send this image to a web method in code-behind.
    Finally, we can save the image in the web method.
    You can refer to the demo below.
    179506-behind.txt
    179905-front.txt
    179508-1.jpg

    Edit

     public static void UploadImage(string imageData)  
            {            
                byte[] data = Convert.FromBase64String(imageData);  
                Document pdfDoc = new Document();           
                var output = new FileStream(HttpContext.Current.Server.MapPath("2.pdf"), FileMode.Create);  
                PdfWriter writer = PdfWriter.GetInstance(pdfDoc, output);  
                pdfDoc.Open();  
                iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(data);  
                 pdfDoc.Add(img);  
                 pdfDoc.Close();             
            }      
            protected void Button1_Click1(object sender, EventArgs e)  
            {  
                Process.Start(Server.MapPath("2.pdf"));  
            }  
    

    179963-8.gif

    Best regards,
    Lan Huang


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