Make .NET snipping tool compatible with multiple monitors

Question

An alternative snipping tool solution was provided in this posting: http://stackoverflow.com/questions/3123776/net-equivalent-of-snipping-tool

Now it's necessary to make it work for selected screens (on multi-monitor systems).

The code has been modified accordingly:

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.WindowState = FormWindowState.Maximized
        Me.Size = New Size(_Screen.Bounds.Width, _Screen.Bounds.Height)
        'Graph.CopyFromScreen(_Screen.Bounds.Left, _Screen.Bounds.Top, _Screen.Bounds.Left, _Screen.Bounds.Top, BitmapSize)
        Graph.CopyFromScreen(Me.Location.X, Me.Location.Y, Me.Location.X, Me.Location.Y, BitmapSize)
    End Sub

End Class

But it refuses to work as expected. The snipper doesn't appear on the selected screen, instead it appears on the first one, regardless of the "screen" parameter in "Snip" function. How to make it work correctly?

UPDATE: The latest snipper version appears on correct screen, but blank.

Answer 1

I don't see you doing anything wrong. I can't test this, don't have the setup right now. Bounds is a bit tricky, there's a bunch of code behind it that ensures that the form can't be displayed off-screen. As an alternative, you could set the Location property instead and override OnLoad() in SnippingTool to set the WindowState property.