MeasureString Using Computer Screen

1- Calculate Screen Rectangle

    Friend Function ScreenToRectangle() As System.Drawing.Rectangle
        Dim rect As System.Drawing.Rectangle = CType(Nothing, System.Drawing.Rectangle)
        Dim devices As System.Windows.Forms.Screen() = System.Windows.Forms.Screen.AllScreens
        For i As Integer = 0 To devices.Length - 1
            Dim device As System.Windows.Forms.Screen = devices(i)
            rect = System.Drawing.Rectangle.Union(rect, device.Bounds)
        Next
        Return rect
    End Function

2- Capture Screen Image

    Friend Function ScreenToImage() As System.Drawing.Image
        Dim screenImage As System.Drawing.Bitmap = New System.Drawing.Bitmap(ScreenToRectangle.Width, ScreenToRectangle.Height)
        Using g As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(screenImage)
            g.CopyFromScreen(ScreenToRectangle.X, ScreenToRectangle.Y, 0, 0, ScreenToRectangle.Size, System.Drawing.CopyPixelOperation.SourceCopy)
        End Using
        Return screenImage
    End Function

3- MeasureString Using graphics and  CharacterRange

   Friend Function MeasureTextSize(g As Graphics, textFont As Font, textToMeasure As String, space As Single) As Size
        Dim charsRegions As Region() = New Region() {}
        Dim rect As RectangleF = New RectangleF(0, 0, ScreenToImage.Width, ScreenToImage.Height)
        Dim ranges As CharacterRange() = New CharacterRange() {New CharacterRange(0, textToMeasure.Length)}
        Using sf As StringFormat = New StringFormat()
            sf.SetMeasurableCharacterRanges(ranges)
            charsRegions = g.MeasureCharacterRanges(textToMeasure, textFont, rect, sf)
            rect = charsRegions(0).GetBounds(g)
        End Using
        Return New Size(CInt((rect.Right + space)), CInt(textFont.GetHeight()))
    End Function

4- MeasureString

   Friend Function MeasureTextSize(textFont As Font, textToMeasure As String, space As Single) As Size
        Dim result As Size = Size.Empty
        Using g As Graphics = Graphics.FromImage(ScreenToImage)
            Dim s As Size = MeasureTextSize(g, textFont, textToMeasure, space)
            result = CType(s, Size)
        End Using
        Return result
    End Function

Usage :

       Dim textSize As Size = CType(Nothing, Size)
        Dim demoText As String = "Demo Text"
        textSize = MeasureTextSize(New Font(Me.Font.FontFamily, 30.0F, Me.Font.Style), demoText, 10.0F)
        Dim result As String = textSize.Width & "," & textSize.Height