在多个控件之上执行 Paint

Question

我有一个小问题。我怎样才能在 controls 之类的任何 textbox 等

之上绘制这种图像

这是我的代码：

Private Sub GroupBox6_Paint(sender As Object, e As PaintEventArgs) Handles GroupBox6.Paint
    If txtStatus.Text = "Cancelled" Then
        Try
            Dim newImage As Image = Image.FromFile(FOLDER_PATH & "\completed.png")
            Dim x As Single = ((GroupBox6.Width / 2) - (463 / 4))
            Dim y As Single = 10
            Dim width As Single = 463 / 2
            Dim height As Single = 242 / 2
            e.Graphics.DrawImage(newImage, x, y, width, height)
        Catch ex As Exception
        End Try
     End If
End Sub

这是我的输出：

所以我的目标是在 groupbox 内的 textbox, label 顶部绘制图像 Completed 有什么想法吗？

Answer 1

您需要两个 bitmaps 和一个 picturebox 才能工作。第一张是 png 图片，第二张是 picturebox 图片：

Private pngImage, picBoxImage As Image

在表单加载事件中初始化两个图像：

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    pngImage = Image.FromFile(FOLDER_PATH & "\completed.png") //load it once
    picBoxImage = CType(pngImage.Clone, Image)

    PictureBox1.Size = New Size(CInt(463 / 2), CInt(242 / 2))
    PictureBox1.Parent = GroupBox6
    PictureBox1.Image = picBoxImage
    PictureBox1.Visible = False //you dont want it at the beggining
End Sub

sub显示图片框：

Private Sub ShowCompletedMessage()
    Dim screenLocation As Point
    Dim gr As Graphics
    //you can pass these values as parameters in the sub if you want to make the code more generic
    Dim x As Integer = CInt(((GroupBox6.Width / 2) - (463 / 4)))
    Dim y As Integer = 10
    Dim width As Integer = CInt(463 / 2)
    Dim height As Integer = CInt(242 / 2)

    //Ensure that picturebox is not visible. If it is you don't need to take a screenshot
    If PictureBox1.Visible = True Then
        Return
    End If

    gr = Graphics.FromImage(picBoxImage)

    //you need to transform the coordinates to screen ones
    screenLocation = GroupBox6.PointToScreen(New Point(x, y))

    //draw the portion of the screen to your bitmap
    gr.CopyFromScreen(screenLocation.X, screenLocation.Y, 0, 0, New Size(width, height), CopyPixelOperation.SourceCopy)

    //draw the png image on top
    gr.DrawImage(pngImage, 0, 0, width, height)

    PictureBox1.Location = New Point(x, y)
    PictureBox1.BringToFront()
    PictureBox1.Visible = True

    gr.Dispose()
    gr = Nothing


    Return

End Sub

每次你想显示消息调用上面的子。您决定何时何地。如果你不再需要它，你需要隐藏picturebox

PictureBox1.Visible = False

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