GDI Overlay On Video Stream (transparency)

[chris36950]

Hi everyone,

I have the following code which is serving as an overlay to a seperate form and was wondering if there was any way that I could make the ellipses transparent like the rest of the background (i.e. empty circles). I cant find out how to do this anywhere and will greatly appreciate any help you can give.

Heres the code:

Public Class Form1
Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

Public Sub New()
MyBase.New()

This call is required by the Windows Form Designer.
InitializeComponent()

Add any initialization after the InitializeComponent() call

End Sub

Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub

Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

NOTE: The following procedure is required by the Windows Form Designer
It can be modified using the Windows Form Designer.
Do not modify it using the code editor.
Friend WithEvents Label1 As System.Windows.Forms.Label
Friend WithEvents Label2 As System.Windows.Forms.Label
Friend WithEvents ToolTip1 As System.Windows.Forms.ToolTip
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.components = New System.ComponentModel.Container
Me.Label1 = New System.Windows.Forms.Label
Me.Label2 = New System.Windows.Forms.Label
Me.ToolTip1 = New System.Windows.Forms.ToolTip(Me.components)
Me.SuspendLayout()

Label1

Me.Label1.Anchor = CType(((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Left) _
Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)
Me.Label1.BackColor = System.Drawing.Color.Yellow
Me.Label1.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle
Me.Label1.Location = New System.Drawing.Point(0, 0)
Me.Label1.Name = "Label1"
Me.Label1.Size = New System.Drawing.Size(392, 24)
Me.Label1.TabIndex = 0
Me.Label1.Text = "Moveable Grid Overlay"
Me.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
Me.ToolTip1.SetToolTip(Me.Label1, "Left Click and Drag to Move Overlay")

Label2

Me.Label2.Anchor = CType((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)
Me.Label2.BackColor = System.Drawing.Color.Red
Me.Label2.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle
Me.Label2.Location = New System.Drawing.Point(392, 0)
Me.Label2.Name = "Label2"
Me.Label2.Size = New System.Drawing.Size(24, 24)
Me.Label2.TabIndex = 1
Me.Label2.Text = "X"
Me.Label2.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
Me.ToolTip1.SetToolTip(Me.Label2, "Click to Close Application")

Form1

Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.BackColor = System.Drawing.Color.White
Me.ClientSize = New System.Drawing.Size(416, 424)
Me.Controls.Add(Me.Label2)
Me.Controls.Add(Me.Label1)
Me.Cursor = System.Windows.Forms.Cursors.Hand
Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None
Me.Name = "Form1"
Me.Text = "Form1"
Me.ToolTip1.SetToolTip(Me, "Click on Point to Toggle its Selection")
Me.TopMost = True
Me.ResumeLayout(False)

End Sub

#End Region

Public Declare Auto Function ReleaseCapture Lib "user32.dll" () As Integer
Public Declare Ansi Function MoveForm Lib "user32.dll" Alias "SendMessageA" _
(ByVal hWnd As IntPtr, Optional ByVal Message As Integer = WM_NCLBUTTONDOWN, _
Optional ByVal HitTest As Integer = HTCAPTION, Optional ByVal wParam As Integer = 0) As Integer

Public Const WM_NCLBUTTONDOWN As Integer = &HA1
Public Const HTCAPTION As Integer = &H2

Private Const xInterval As Integer = 30
Private Const yInterval As Integer = 30
Private Const radius As Integer = 4

Private selections As New ArrayList
Private rectangles As New ArrayList

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim x As Integer
Dim y As Integer

Dim rect As Rectangle
Dim gp As New System.Drawing.Drawing2D.GraphicsPath

gp.AddRectangle(New Rectangle(Label1.Location, Label1.Size))
gp.AddRectangle(New Rectangle(Label2.Location, Label2.Size))
For x = xInterval To Me.Width Step xInterval
For y = (Label1.Top + Label1.Height + yInterval) To Me.Height Step yInterval
rect = New Rectangle(x - radius, y - radius, radius * 2, radius * 2)
gp.AddEllipse(rect)
rectangles.Add(rect)
Next
Next

Me.Region = New Region(gp)
End Sub

Private Sub Label1_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles Label1.MouseEnter
Label1.ForeColor = Color.Red
End Sub

Private Sub Label1_MouseLeave(ByVal sender As Object, ByVal e As System.EventArgs) Handles Label1.MouseLeave
Label1.ForeColor = Color.Black
End Sub

Private Sub Label1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseDown
If e.Button = MouseButtons.Left Then
ReleaseCapture()
MoveForm(Me.Handle)
End If
End Sub

Private Sub Label2_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles Label2.MouseEnter
Label2.ForeColor = Color.Yellow
End Sub

Private Sub Label2_MouseLeave(ByVal sender As Object, ByVal e As System.EventArgs) Handles Label2.MouseLeave
Label2.ForeColor = Color.Black
End Sub

Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click
Me.Close()
End Sub

Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
Dim rect As Rectangle
Dim pt As New Point(e.X, e.Y)
For Each rect In rectangles
If rect.Contains(pt) Then
If selections.Contains(rect) Then
selections.Remove(rect)
Else
selections.Add(rect)
End If
Me.Refresh()
Exit Sub
End If
Next
End Sub

Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
Dim rect As Rectangle
For Each rect In selections
e.Graphics.FillEllipse(Brushes.Red, rect)
Next
End Sub

End Class

 

[chris36950]

I guess this is one of those things that isnt easily done without the use of Drawing2D, huh?