WPF Web Browser Control and DPI Scaling

Question

I\'m working with a WPF application that uses the Web Browser control and I\'m having issues with High DPI scaling.

It looks like the Web Browser control is not properl

Answer 1

You need to determine the browser zoom percentage from the OS dpi, then set the browser zoom via its ActiveX wrapper. Unfortunately, the wrapper is not exposed in WPF so you'll need to add a reference to "Microsoft Internet Controls" and use reflection to get it.

Private Sub Browser_LoadCompleted(sender As Object, e As NavigationEventArgs)
    Dim source = PresentationSource.FromDependencyObject(sender)
    Dim matrix As Matrix = source.CompositionTarget.TransformToDevice
    If matrix.Determinant > 1 Then
        Dim zoomLevel As Integer = matrix.Determinant * 100
        Dim ie As SHDocVw.InternetExplorer = GetType(WebBrowser).GetField("_axIWebBrowser2", BindingFlags.Instance Or BindingFlags.NonPublic).GetValue(sender)
        ie.ExecWB(SHDocVw.OLECMDID.OLECMDID_OPTICAL_ZOOM, SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DONTPROMPTUSER, zoomLevel, IntPtr.Zero)
    End If
End Sub

Additional reading:

https://dzimchuk.net/best-way-to-get-dpi-value-in-wpf/

https://weblog.west-wind.com/posts/2016/Aug/22/Detecting-and-Setting-Zoom-Level-in-the-WPF-WebBrowser-Control