En esta publicación se proporcionó una solución alternativa de herramienta de recorte:.NET Equivalente de herramienta de recorte

Ahora es necesario que funcione para pantallas seleccionadas (en sistemas de monitores múltiples).

El código ha sido modificado en consecuencia:

Public Class SnippingTool


    Private Shared _Screen As Screen

    Private Shared BitmapSize As Size

    Private Shared Graph As Graphics


    Public Shared Function Snip(ByVal screen As Screen) As Image

        _Screen = screen

        Dim bmp As New Bitmap(screen.Bounds.Width, screen.Bounds.Height, System.Drawing.Imaging.PixelFormat.Format32bppPArgb)

        Dim gr As Graphics = Graphics.FromImage(bmp)

        Graph = gr


        gr.SmoothingMode = Drawing2D.SmoothingMode.None '###

        BitmapSize = bmp.Size


        Using snipper = New SnippingTool(bmp)

            snipper.Location = New Point(screen.Bounds.Left, screen.Bounds.Top)

            If snipper.ShowDialog() = DialogResult.OK Then
                Return snipper.Image
            End If

        End Using

        Return Nothing


    End Function



    Public Sub New(ByVal screenShot As Image)
        InitializeComponent()
        Me.BackgroundImage = screenShot
        Me.ShowInTaskbar = False
        Me.FormBorderStyle = FormBorderStyle.None


        'Me.WindowState = FormWindowState.Maximized

        Me.DoubleBuffered = True
    End Sub
    Public Property Image() As Image
        Get
            Return m_Image
        End Get
        Set(ByVal value As Image)
            m_Image = Value
        End Set
    End Property
    Private m_Image As Image


    Private rcSelect As New Rectangle()
    Private pntStart As Point

    Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
        ' Start the snip on mouse down
        If e.Button <> MouseButtons.Left Then
            Return
        End If
        pntStart = e.Location
        rcSelect = New Rectangle(e.Location, New Size(0, 0))
        Me.Invalidate()
    End Sub
    Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs)
        ' Modify the selection on mouse move
        If e.Button <> MouseButtons.Left Then
            Return
        End If
        Dim x1 As Integer = Math.Min(e.X, pntStart.X)
        Dim y1 As Integer = Math.Min(e.Y, pntStart.Y)
        Dim x2 As Integer = Math.Max(e.X, pntStart.X)
        Dim y2 As Integer = Math.Max(e.Y, pntStart.Y)
        rcSelect = New Rectangle(x1, y1, x2 - x1, y2 - y1)
        Me.Invalidate()
    End Sub


    Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs)
        ' Complete the snip on mouse-up
        If rcSelect.Width <= 0 OrElse rcSelect.Height <= 0 Then
            Return
        End If
        Image = New Bitmap(rcSelect.Width, rcSelect.Height)
        Using gr As Graphics = Graphics.FromImage(Image)
            gr.DrawImage(Me.BackgroundImage, New Rectangle(0, 0, Image.Width, Image.Height), rcSelect, GraphicsUnit.Pixel)
        End Using
        DialogResult = DialogResult.OK
    End Sub
    Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        ' Draw the current selection
        Using br As Brush = New SolidBrush(Color.FromArgb(120, Color.White))
            Dim x1 As Integer = rcSelect.X
            Dim x2 As Integer = rcSelect.X + rcSelect.Width
            Dim y1 As Integer = rcSelect.Y
            Dim y2 As Integer = rcSelect.Y + rcSelect.Height
            e.Graphics.FillRectangle(br, New Rectangle(0, 0, x1, Me.Height))
            e.Graphics.FillRectangle(br, New Rectangle(x2, 0, Me.Width - x2, Me.Height))
            e.Graphics.FillRectangle(br, New Rectangle(x1, 0, x2 - x1, y1))
            e.Graphics.FillRectangle(br, New Rectangle(x1, y2, x2 - x1, Me.Height - y2))
        End Using
        Using pen As New Pen(Color.Red, 3)
            e.Graphics.DrawRectangle(pen, rcSelect)
        End Using
    End Sub
    Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
        ' Allow canceling the snip with the Escape key
        If keyData = Keys.Escape Then
            Me.DialogResult = DialogResult.Cancel
        End If
        Return MyBase.ProcessCmdKey(msg, keyData)
    End Function

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)
        Me.Size = New Size(_Screen.Bounds.Width, _Screen.Bounds.Height)
        Dim area = _Screen.WorkingArea
        Graph.CopyFromScreen(area.X, area.Y, area.Y, area.Y, BitmapSize)
    End Sub

End Class

Pero se niega a trabajar como se esperaba. El snipper no aparece en la pantalla seleccionada, sino que aparece en la primera, independientemente del parámetro "pantalla" en la función "Snip". ¿Cómo hacer que funcione correctamente?

ACTUALIZAR: La última versión de snipper aparece en la pantalla correcta, pero en blanco.

ACTUALIZACIÓN X2 : El código anterior se ha actualizado para reflejar la última versión, que ahora funciona correctamente.