这段代码有什么问题，无法在 VB.net2005 中的图片框中裁剪图像X1？

Question

我正在创建一个在picturebox1中裁剪图像的应用程序。它有两个按钮：-Button1= 捕获桌面并将屏幕截图放入图片框 1。背后有这段代码

Imports System.Net.Mail
Public Class Form1
    Private SelectSiz As Size
    Private SelectPos As System.Drawing.Point
    Private Selecting As Boolean = False
    Private Selected As Boolean = False
    Private source As Image
    Dim XOffs As Integer
    Dim YOffs As Integer
    Private Function cc() As Bitmap
        Dim s As Screen = Screen.PrimaryScreen
        Dim img As New Bitmap(s.Bounds.Width, s.Bounds.Height)
        Dim gr As Graphics = Graphics.FromImage(img)
        gr.CopyFromScreen(s.Bounds.Location, Point.Empty, s.Bounds.Size)
        Return img
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.PictureBox1.Image = cc()
    End Sub
Button2= that crop slected area which user had made it onto image.
with this code behind it
     Private Sub Button2_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        If Selected Then
            Dim Cropped As Image = New Bitmap(Math.Abs(SelectSiz.Width), Math.Abs(SelectSiz.Height))
            Dim g As Graphics = Graphics.FromImage(Cropped)
            Dim SrcRect As Rectangle = GetSelection(SelectPos, SelectSiz)
            SrcRect.X += XOffs
            SrcRect.Y += YOffs
            g.DrawImage(source, New Rectangle(0, 0, Cropped.Width, Cropped.Height), SrcRect, GraphicsUnit.Pixel)
            PictureBox1.Image = Cropped
            Button3.Enabled = True
            Button4.Enabled = True
            Button7.Enabled = True
        End If
        Selected = False
    End Sub

但是现在的问题是，当我选择一个区域将其裁剪到图像上并按 Button2 裁剪它时，它会给我这个错误：-{"值不能为空。参数名称：图像"}
在此处输入图像描述

这是我的应用程序的图片在此处输入图像描述

这就是整个代码

Imports System.Net.Mail
Public Class Form1
    Private SelectSiz As Size
    Private SelectPos As System.Drawing.Point
    Private Selecting As Boolean = False
    Private Selected As Boolean = False
    Private source As Image
    Dim XOffs As Integer
    Dim YOffs As Integer
    Private Function cc() As Bitmap
        Dim s As Screen = Screen.PrimaryScreen
        Dim img As New Bitmap(s.Bounds.Width, s.Bounds.Height)
        Dim gr As Graphics = Graphics.FromImage(img)
        gr.CopyFromScreen(s.Bounds.Location, Point.Empty, s.Bounds.Size)
        Return img
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.PictureBox1.Image = cc()
    End Sub
    Private Sub Button2_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        If Selected Then
            Dim Cropped As Image = New Bitmap(Math.Abs(SelectSiz.Width), Math.Abs(SelectSiz.Height))
            Dim g As Graphics = Graphics.FromImage(Cropped)
            Dim SrcRect As Rectangle = GetSelection(SelectPos, SelectSiz)
            SrcRect.X += XOffs
            SrcRect.Y += YOffs
            g.DrawImage(source, New Rectangle(0, 0, Cropped.Width, Cropped.Height), SrcRect, GraphicsUnit.Pixel)
            PictureBox1.Image = Cropped
            Button3.Enabled = True
            Button4.Enabled = True
            Button7.Enabled = True
        End If
        Selected = False
    End Sub
    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseDown
        Selecting = True
        SelectPos = New Point(e.Location)
        SelectSiz = New Size(1, 1)
        Me.Refresh()
    End Sub
    Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseMove
        If Selecting Then
            SelectSiz = New Size(e.Location.X - SelectPos.X, e.Location.Y - SelectPos.Y)
            Selected = True
            Me.Refresh()
        End If
    End Sub
    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseUp
        Selecting = False
    End Sub
    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles PictureBox1.Paint
        If Selected Then
            e.Graphics.DrawRectangle(Pens.Black, GetSelection(SelectPos, SelectSiz))
        End If
    End Sub
    Public Function GetSelection(ByVal Start As Point, ByVal Range As Size) As Rectangle
        Dim X As Integer = Start.X
        Dim X1 As Integer = Range.Width
        If X1 < 0 Then
            X1 = Math.Abs(X1)
            X -= X1
        End If
        Dim Y As Integer = Start.Y
        Dim Y1 As Integer = Range.Height
        If Y1 < 0 Then
            Y1 = Math.Abs(Y1)
            Y -= Y1
        End If
        Return New Rectangle(X, Y, X1, Y1)
    End Function
    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim img As Image = Me.PictureBox1.Image
        img.RotateFlip(RotateFlipType.Rotate90FlipNone)
        Me.PictureBox1.Image = img
    End Sub
    Private Sub PictureBox1_MouseWhee(ByVal sender As System.Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseWheel
        If e.Delta <> 0 Then
            If e.Delta <= 0 Then
                If PictureBox1.Width < 500 Then Exit Sub 'minimum 500?
            Else
                If PictureBox1.Width > 2000 Then Exit Sub 'maximum 2000?
            End If
            PictureBox1.Width += CInt(PictureBox1.Width * e.Delta / 1000)
            PictureBox1.Height += CInt(PictureBox1.Height * e.Delta / 1000)
        End If
    End Sub
    Private Sub PictureBox1_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles PictureBox1.MouseEnter
        PictureBox1.Focus()
    End Sub

End Class

提前感谢

Answer 1

终于我做到了，谢谢大家这是代码

 Me.Opacity = 0%
        Me.PictureBox1.Image = cc()
        Dim filename As String = String.Format("image{0:yyyyMMddHHmmss}.png", DateTime.Now)
        Dim filePath = (IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), (filename)))
        PictureBox1.Image.Save(filePath)
        source = Image.FromFile(filePath)
        PictureBox1.Image = source
        Me.Opacity = 100%
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try