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I have a Webview2 Control in my application, used to view PDF documents.
The application also stores to and reads from MS SQL server PDFs data.
Currently, I am retrieving binary data from SQL, convert them to a temporary file to disk and set:
webview2.source = New Uri("file://" + filename)
That's working fine so far, but of course I would like to do the job without writing and reading to and from disk.
Is there a way to do the same without accessing the disk?
Update (as recommended), what I tried. With part of code for better understandg:
Dim fieldOrdinal = reader.GetOrdinal(ColumnName)
reader.Read()
Dim blob = New Byte(reader.GetBytes(fieldOrdinal, 0, Nothing, 0, 0) - 1) {}
reader.GetBytes(fieldOrdinal, 0, blob, 0, blob.Length)
Dim pdfBase64 As String = Convert.ToBase64String(blob)
Dim html As String = "<!DOCTYPE html><html><head></head><body><div>" & $"<iframe width=100% height=500 src=\" & Chr(&H22) & "data:Application/pdf;base64,{pdfBase64}\" & Chr(&H22) & ">" & "</iframe></div></body></html>"
The webview2 control shows a frame, but without content
Final Update: Here the (correct) to VB translated and working code:
Dim html As String = "<!DOCTYPE html><html><head></head><body><div>" & $"<iframe width=100% height=500 src=""data:Application/pdf;base64,{pdfBase64}"">" & "</iframe></div></body></html>"
859
asked Jul 28 '26 13:07
You can embed the PDF in an IFRAME as Base64, the same way you embed images.
In this case, the mime type is of course application/pdf.
Convert to Base64 your source PDF bytes with Convert.ToBase64String(), use a standard HTML5 header and set the IFRAME and/or DIV container to the desired size.
Use the WebView2.NavigateToString() method to load the HTML with the embedded PDF:
2097152 bytes (2MB)string pdfBase64 = Convert.ToBase64String([Your PDF bytes]);
string html = "<!DOCTYPE html><html><head></head><body><div>" +
$"<iframe width=100% height=500 src=\"data:application/pdf;base64,{pdfBase64}\">" +
"</iframe></div></body></html>";
webView2.NavigateToString(html);
VB.Net version:
Dim pdfBytes = [DataReader].GetSqlBytes([DataReader].GetOrdinal("[Column Name]")).Value
Dim pdfBase64 As String = Convert.ToBase64String(pdfBytes)
Dim html As String = "<!DOCTYPE html><html><head></head><body><div>" &
$"<iframe width=100% height=500 src=""data:Application/pdf;base64,{pdfBase64}"">" &
"</iframe></div></body></html>"
webView2.NavigateToString(html)
The iframe size should not be set like that, you should use CSS styles (and probably a simple JavaScript to handle late redefinition of the size of the Window that contains your PDF).
You could build a simple HTML template and fill the Base64 content as described.
129
Just to finalize the answer. Below the final version I'm using, including CSS in the framing HTML to make the pdf borderless and 100% x 100% size of the parent webview2:
Dim pdfBase64 As String = Convert.ToBase64String(pdfBytes)
Dim html As String = "<!DOCTYPE html><html><head>
</head>
<style>
body {margin: 0;}
iframe {display: block; background: #000; border: none; height: 100vh; width: 100vw;}
</style>
<body>" & $"<iframe src=""data:Application/pdf;base64,{pdfBase64}"">" & "</iframe></body></html>"
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