Creating a Custom Polygon Class in vb.net - vb.net

Question

I want to make a custom polygon shape class, which i can drag and drop unto my form at will (just as it is done in the case of OvalShape and RectangleShape objects in VS toolbox). I checked site1, site2 and site3, one of which specifically said that the OnPaint Event of my form should be overridden. Is there any way I can achieve the same while creating the custom polygon shape, and still have my polygon appear on the toolbox?
Edit:
#Jens: I'll like the control to generate its code with the following tested code:
Me.ClientSize = New Point(24, 24)
Dim r1 As Integer = Min(cx, cy) - 10
Dim r2 As Integer = Min(cx, cy) \ 2
Dim pts(9) As Point
For i As Integer = 0 To 9 Step 2
pts(i).X = cx + CInt(r1 * Cos(i * PI / 5 - PI / 2))
pts(i).Y = cy + CInt(r1 * Sin(i * PI / 5 - PI / 2))
pts(i + 1).X = cx + CInt(r2 * Cos((i + 1) * PI / 5 - PI / 2))
pts(i + 1).Y = cy + CInt(r2 * Sin((i + 1) * PI / 5 - PI / 2))
Next i
That gives me a star with 5 spikes. How can i store them in the Points variable created,
OR
store the points as a region so that whenever i change forecolor, it fills the region (i.e. polygn) with the selected color. I also want to prevent painting the backcolor. Please take a look at the links below to a c# solution of what i really want, but i suck at converting c# to vb.
link1; Link2
Thanks a lot

Answer 1

I am not entirely sure that that is what you want. You can always derive a new class from Control and use its Paint event to draw whatever you like. In your case a polygon.
The control therefore contains a Points property that is just an array of PointF values that define the edges of the polygon. By using the DesignerSerializationVisible.Content attribute you make it possible to edit these values through the designer directly. The code looks like this:
Public Class PolygonControl
Inherits Control
Private _Points(2) As PointF
<System.ComponentModel.DesignerSerializationVisibility(System.ComponentModel.DesignerSerializationVisibility.Content)>
Public Property Points As PointF()
Get
Return _Points
End Get
Set(value As PointF())
_Points = value
End Set
End Property
Public Property LineColor As Color = Color.Black
Public Property LineWidth As Integer = 2
Private Sub PolygonControl_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
e.Graphics.Clear(Me.BackColor)
If Points IsNot Nothing AndAlso Points.Count > 1 Then
e.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
Using b As New SolidBrush(ForeColor)
Using p As New Pen(b, LineWidth)
e.Graphics.DrawPolygon(p, Points)
End Using
End Using
End If
End Sub
End Class
I added a color and width property as well. This is just to give you a rough idea. Notice the attribute above the Points property.
In "action" it looks like this:
Adding better designer support is certainly possible, but I have no experience with that whatsoever. But it is a start.
Edit
Since you always draw the same shape, you can precalculate the points in the control's constructor and just draw the shape in the paint event:
Public Class StarControl
Inherits Control
'Storage for the shape's points
Private pts(9) As Point
'Constructor
Public Sub New()
Me.ClientSize = New Size(24, 24)
SetStyle(ControlStyles.SupportsTransparentBackColor, True)
Me.BackColor = Color.Transparent
'Precalculate the shape
Dim cx = CInt(Me.ClientSize.Width / 2)
Dim cy = CInt(Me.ClientSize.Height / 2)
Dim r1 As Integer = Min(cx, cy) - 10
Dim r2 As Integer = Min(cx, cy) \ 2
ReDim pts(9)
For i As Integer = 0 To 9 Step 2
pts(i).X = cx + CInt(r1 * Cos(i * PI / 5 - PI / 2))
pts(i).Y = cy + CInt(r1 * Sin(i * PI / 5 - PI / 2))
pts(i + 1).X = cx + CInt(r2 * Cos((i + 1) * PI / 5 - PI / 2))
pts(i + 1).Y = cy + CInt(r2 * Sin((i + 1) * PI / 5 - PI / 2))
Next i
End Sub
Public Property LineColor As Color = Color.Black
Public Property FillColor As Color = Color.Gold
Public Property LineWidth As Integer = 1
Public Sub PaintMe(sender As Object, e As PaintEventArgs) Handles Me.Paint
'Draw the precalculated shape
e.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
Using b As New SolidBrush(FillColor)
e.Graphics.FillPolygon(b, pts)
End Using
Using b As New SolidBrush(LineColor)
Using p As New Pen(b, LineWidth)
e.Graphics.DrawPolygon(p, pts)
End Using
End Using
End Sub
End Class
For an even cooler effect move the shape calculation into the Paint event handler so the shape resizes itself based on the control's size. This allows you to draw stars of arbitrary size.