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WPF Aero Glass DPI Setting Mismatch

I have a WPF application using Aero Glass. When using the application under a 120dpi setting the margins within my UI are not matching up to the margins I pass over to the DwmExtendFrameIntoClientArea API call.

How would I get the systems DPI setting within .NET 3.0 so that I can correct the margin that I am passing to the DwmExtendFrameIntoClientArea API call?

Essentially, the WPF UI uses device-independent units whereas the DwmExtendFrameIntoClientArea API call uses pixels.

Thanks

Solution

  • Okay, something like the following will fix the issue:

    Public Shared Function GetDpiAdjustedMargins(ByVal WindowHandle As IntPtr, ByVal Left As Integer, ByVal Right As Integer, ByVal Top As Integer, ByVal Bottom As Integer) As Margins
    '
    Dim Graphics As System.Drawing.Graphics = System.Drawing.Graphics.FromHwnd(WindowHandle)
    Dim DesktopDPIx As Single = Graphics.DpiX
    Dim DesktopDPIy As Single = Graphics.DpiY

    Dim Margins As Margins = New Margins
    Margins.Left = Left * (DesktopDPIx / 96)
    Margins.Right = Right * (DesktopDPIx / 96)
    Margins.Top = Top * (DesktopDPIx / 96)
    Margins.Bottom = Bottom * (DesktopDPIx / 96)
    Return Margins
    '
End Function



    Source: Pro WPF in C# 2008 By Matthew MacDonald