DPI trouble with manual correction of location and size

[VisualBeginner.NET]

I am using Visual Studio 2019 (2022 messes up even more) with Visual Basic .NET framework 3.5 (3.7.2 gives even more headaches).

Earlier I could screen capture with

        
        Dim img As New Bitmap(frm.ClientSize.Width, frm.ClientSize.Height)
        Using gr As Graphics = Graphics.FromImage(img)
            gr.CopyFromScreen(frm.PointToScreen(frm.ClientRectangle.Location), Point.Empty, frm.ClientSize)
        End Using
        img.Save(filename, Imaging.ImageFormat.Png)

But this does not work on my newer computer with 125% scaling. So I have been trying this which does not work:

    Sub SaveFromScreen(frm As Form, fil As String)

        Dim g As Graphics = frm.CreateGraphics()
        Dim xDpi As Single = g.DpiX
        Dim scrScale As Single = CSng(xDpi) / 96.0

        Dim bmpWidth As Short = frm.ClientSize.Width * scrScale
        Dim bmpHeight As Short = frm.ClientSize.Height * scrScale

        Dim img As New Bitmap(bmpWidth, bmpHeight)

        Dim scrX1 As Integer = frm.ClientRectangle.Location.X * scrScale
        Dim scrY1 As Integer = frm.ClientRectangle.Location.Y * scrScale

        g.CopyFromScreen(scrX1, scrY1, 0, 0, img.Size, CopyPixelOperation.SourceCopy)
        img.Save(fil & ".png", Imaging.ImageFormat.Png)
        img.Save(fil & ".bmp", Imaging.ImageFormat.Bmp)

    End Sub

Please tell me where I am wrong or how to correct this. Thank you very much for any help.

[dday9]

There are a couple of things off the bat that you should be doing. The first is to wrap your code that implements IDisposable in Using statements. The second is to avoid defining bmpWidth and height as Shorts, instead you should probably be casting these to Integers. Finally, I think you should be using PointToScreen which would automatically take into account the DPI scaling.

Take a look at this example:

Public Shared Sub SaveFromScreen(frm As Form, fileName As String)
    Using g = frm.CreateGraphics()
        Dim xDpi = g.DpiX
        Dim scrScale = xDpi / 96.0

        Dim bmpWidth = Convert.ToInt32(frm.ClientSize.Width * scrScale)
        Dim bmpHeight = Convert.ToInt32(frm.ClientSize.Height * scrScale)

        Using img As New Bitmap(bmpWidth, bmpHeight)
            Using gfx = Graphics.FromImage(img)
                Dim scrX1 = Convert.ToInt32(frm.PointToScreen(frm.ClientRectangle.Location).X)
                Dim scrX2 = Convert.ToInt32(scrX1 + frm.ClientSize.Width)

                Dim scrY1 = Convert.ToInt32(frm.PointToScreen(frm.ClientRectangle.Location).Y)
                Dim scrY2 = Convert.ToInt32(scrY1 + frm.ClientSize.Height)

                gfx.CopyFromScreen(scrX1, scrY1, 0, 0, img.Size, CopyPixelOperation.SourceCopy)
            End Using

            img.Save($"{fileName}.png", Imaging.ImageFormat.Png)
            img.Save($"{fileName}.bmp", Imaging.ImageFormat.Bmp)
        End Using
    End Using
End Sub

[VisualBeginner.NET]

Your corrected code also did not work. It is still not locating the corners correctly.

Surprisingly, this shows DPI at 96, so scrScale was 1.

I added a line
scrScale = 1.25
to change scrScale to 1.25 to check if the rest was working, but it did not help. It was still wrong. Even the size is wrong. So I tried without scrScale, and still it did not work. I checked with scrScale = 0.8 and still it does not work. Any idea where the trouble is?

Thanks for your help.

There are a couple of things off the bat that you should be doing. The first is to wrap your code that implements IDisposable in Using statements. The second is to avoid defining bmpWidth and height as Shorts, instead you should probably be casting these to Integers. Finally, I think you should be using PointToScreen which would automatically take into account the DPI scaling.

Take a look at this example:

Public Shared Sub SaveFromScreen(frm As Form, fileName As String)
    Using g = frm.CreateGraphics()
        Dim xDpi = g.DpiX
        Dim scrScale = xDpi / 96.0

        Dim bmpWidth = Convert.ToInt32(frm.ClientSize.Width * scrScale)
        Dim bmpHeight = Convert.ToInt32(frm.ClientSize.Height * scrScale)

        Using img As New Bitmap(bmpWidth, bmpHeight)
            Using gfx = Graphics.FromImage(img)
                Dim scrX1 = Convert.ToInt32(frm.PointToScreen(frm.ClientRectangle.Location).X)
                Dim scrX2 = Convert.ToInt32(scrX1 + frm.ClientSize.Width)

                Dim scrY1 = Convert.ToInt32(frm.PointToScreen(frm.ClientRectangle.Location).Y)
                Dim scrY2 = Convert.ToInt32(scrY1 + frm.ClientSize.Height)

                gfx.CopyFromScreen(scrX1, scrY1, 0, 0, img.Size, CopyPixelOperation.SourceCopy)
            End Using

            img.Save($"{fileName}.png", Imaging.ImageFormat.Png)
            img.Save($"{fileName}.bmp", Imaging.ImageFormat.Bmp)
        End Using
    End Using
End Sub