vb.net Screen Capture of form2 with form1

Question

i have a problem here. I have a form1 which i use to get settings en so on. But there is also a panel that i want to use to see whats inside form2.

Form2 = a fullscreen form without formborderstyles

This form2 shows information on a big screen and i need to see in my form1 (in this panel) the entire content of form2 like a screencapture thing.

Can someone help?

Answer 1

A Panel will produce flickering problems in WindowsForms, I suggest you to place a PictureBox inside the Panel with the PictureBox.Dock = Fill property set (or just use only the PictureBox instead of a Panel) then you could use for example my TakeScreenshotFromForm() function from my ElektroKit Framework.

A full working example:

Imports System.Drawing.Drawing2D
Imports System.Drawing.Imaging

Public Class Form1 : Inherits Form

    Friend WithEvents ScreenshotTimer As New System.Windows.Forms.Timer

    Private Sub Test() Handles MyBase.Shown

        Form2.Show()

        With Me.ScreenshotTimer
            .Interval = 100
            .Enabled = True
            .Start()
        End With

        Me.PictureBox1.BackgroundImageLayout = ImageLayout.Stretch

    End Sub

    Private Sub ScreenshotTimer_Tick(sender As Object, e As EventArgs) Handles ScreenshotTimer.Tick

        If Me.PictureBox1.BackgroundImage IsNot Nothing Then
            Me.PictureBox1.BackgroundImage.Dispose()
        End If

        Me.PictureBox1.BackgroundImage = TakeScreenshotFromForm(Form2, includeMouse:=True)

    End Sub

    Public Shared Function TakeScreenshotFromForm(ByVal f As Form,
                                                  Optional ByVal includeMouse As Boolean = False,
                                                  Optional ByVal pixelFormat As PixelFormat = PixelFormat.Format24bppRgb) As Image

        If Not f.Visible Then
            Return Nothing
        End If

        Dim bmp As New Bitmap(f.Size.Width, f.Size.Height, pixelFormat)

        Using g As Graphics = Graphics.FromImage(bmp)

            g.InterpolationMode = InterpolationMode.Default
            g.PixelOffsetMode = PixelOffsetMode.Default
            g.CopyFromScreen(f.Location, New Drawing.Point(0, 0), f.Size)

            ' Draw the cursor in the image.
            If includeMouse Then

                Dim cursorSize As System.Drawing.Size = CType(f.Cursor.HotSpot, System.Drawing.Size)
                cursorSize.Width -= ((f.Size.Width - f.ClientSize.Width) \ 2)
                cursorSize.Height -= ((f.Size.Height - f.ClientSize.Height) - ((f.Size.Width - f.ClientSize.Width) \ 2))

                Dim formPoint As Drawing.Point = f.PointToClient(Drawing.Point.Subtract(Control.MousePosition, cursorSize))

                Cursors.Arrow.Draw(g, New Rectangle(formPoint.X, formPoint.Y, cursorSize.Width, cursorSize.Height))

            End If

        End Using

        Return bmp

    End Function

End Class

Instead of the methodology that I use, you can also use the Control.DrawToBitmap() method to properlly capture the Form when is not visible (totally invisible on the screen, or covered by other windows), but the resulting image will not contain some "information", such as a TextBox caret for example.

Dim bmp As New Bitmap(f.Bounds.Size.Width, f.Bounds.Size.Height, pixelFormat)
f.DrawToBitmap(bmp, New Rectangle(0, 0, f.Bounds.Size.Width, f.Bounds.Size.Height))
' ...