VB.Net Tutorial/2D Graphics/Polygon

Draw a Polygon

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
public class DrawPolygon
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
public class Form1
  Inherits System.Windows.Forms.Form
  Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        
        Dim points(3) As System.Drawing.Point
        points(0) = New Point(120, 60) "Top Left of Trapezoid
        points(1) = New Point(180, 60) "Top Right of Trapezoid
        points(2) = New Point(240, 120) "Bottom Right of Trapezoid
        points(3) = New Point(60, 120) "Bottom Left of Trapezoid
        e.Graphics.DrawPolygon(New Pen(Color.Blue), points)
  End Sub
  Public Sub New()
   
    MyBase.New()
    Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
    Me.ClientSize = New System.Drawing.Size(292, 273)
    Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
  End Sub
End Class

Trapezoid

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
public class DrawPolygon
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
public class Form1
  Inherits System.Windows.Forms.Form
  Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        
        Dim points(3) As System.Drawing.Point
        points(0) = New Point(120, 60) "Top Left of Trapezoid
        points(1) = New Point(180, 60) "Top Right of Trapezoid
        points(2) = New Point(240, 120) "Bottom Right of Trapezoid
        points(3) = New Point(60, 120) "Bottom Left of Trapezoid
        e.Graphics.DrawPolygon(New Pen(Color.Blue), points)
  End Sub
  Public Sub New()
   
    MyBase.New()
    Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
    Me.ClientSize = New System.Drawing.Size(292, 273)
    Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
  End Sub
End Class

Use mouse to draw a polygon

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
Imports System.Collections
public class DrawPolygon
   public Shared Sub Main
        Application.Run(New FrmPolygon)
   End Sub
End class

Public Class FrmPolygon
   Inherits System.Windows.Forms.Form
   " polygon type options
   Friend WithEvents filledPolygonRadio As RadioButton
   Friend WithEvents lineRadio As RadioButton
   Friend WithEvents polygonRadio As RadioButton
   " command buttons
   Friend WithEvents cmdClear As Button
   Friend WithEvents cmdNewColor As Button
   Friend WithEvents drawWindow As Panel
   Friend WithEvents typeGroup As GroupBox

#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.ruponentModel.Container
   "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.
   <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
      Me.typeGroup = New System.Windows.Forms.GroupBox()
      Me.filledPolygonRadio = New System.Windows.Forms.RadioButton()
      Me.lineRadio = New System.Windows.Forms.RadioButton()
      Me.polygonRadio = New System.Windows.Forms.RadioButton()
      Me.drawWindow = New System.Windows.Forms.Panel()
      Me.cmdClear = New System.Windows.Forms.Button()
      Me.cmdNewColor = New System.Windows.Forms.Button()
      Me.typeGroup.SuspendLayout()
      Me.SuspendLayout()
      "
      "typeGroup
      "
      Me.typeGroup.Controls.AddRange(New System.Windows.Forms.Control() {Me.filledPolygonRadio, Me.lineRadio, Me.polygonRadio})
      Me.typeGroup.Location = New System.Drawing.Point(232, 8)
      Me.typeGroup.Name = "typeGroup"
      Me.typeGroup.Size = New System.Drawing.Size(128, 104)
      Me.typeGroup.TabIndex = 0
      Me.typeGroup.TabStop = False
      Me.typeGroup.Text = "Select Type"
      "
      "filledPolygonRadio
      "
      Me.filledPolygonRadio.Location = New System.Drawing.Point(8, 80)
      Me.filledPolygonRadio.Name = "filledPolygonRadio"
      Me.filledPolygonRadio.Size = New System.Drawing.Size(112, 16)
      Me.filledPolygonRadio.TabIndex = 2
      Me.filledPolygonRadio.Text = "Filled Polygon"
      "
      "lineRadio
      "
      Me.lineRadio.Location = New System.Drawing.Point(8, 24)
      Me.lineRadio.Name = "lineRadio"
      Me.lineRadio.Size = New System.Drawing.Size(112, 16)
      Me.lineRadio.TabIndex = 1
      Me.lineRadio.Text = "Lines"
      "
      "polygonRadio
      "
      Me.polygonRadio.Location = New System.Drawing.Point(8, 48)
      Me.polygonRadio.Name = "polygonRadio"
      Me.polygonRadio.Size = New System.Drawing.Size(112, 24)
      Me.polygonRadio.TabIndex = 0
      Me.polygonRadio.Text = "Polygon"
      "
      "drawWindow
      "
      Me.drawWindow.BackColor = System.Drawing.SystemColors.Window
      Me.drawWindow.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
      Me.drawWindow.Name = "drawWindow"
      Me.drawWindow.Size = New System.Drawing.Size(232, 264)
      Me.drawWindow.TabIndex = 1
      "
      "cmdClear
      "
      Me.cmdClear.Location = New System.Drawing.Point(240, 160)
      Me.cmdClear.Name = "cmdClear"
      Me.cmdClear.Size = New System.Drawing.Size(112, 24)
      Me.cmdClear.TabIndex = 2
      Me.cmdClear.Text = "Clear"
      "
      "cmdNewColor
      "
      Me.cmdNewColor.Location = New System.Drawing.Point(240, 192)
      Me.cmdNewColor.Name = "cmdNewColor"
      Me.cmdNewColor.Size = New System.Drawing.Size(112, 24)
      Me.cmdNewColor.TabIndex = 3
      Me.cmdNewColor.Text = "Change Color"
      "
      "FrmPolygon
      "
      Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
      Me.ClientSize = New System.Drawing.Size(360, 269)
      Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.cmdNewColor, Me.cmdClear, Me.drawWindow, Me.typeGroup})
      Me.Name = "FrmPolygon"
      Me.Text = "Drawing Polygons"
      Me.typeGroup.ResumeLayout(False)
      Me.ResumeLayout(False)
   End Sub
#End Region
   Private mPoints As ArrayList = New ArrayList()
   Dim mPen As Pen = New Pen(Color.DarkBlue)
   Dim mBrush As SolidBrush = New SolidBrush(Color.DarkBlue)
   Private Sub drawWindow_MouseDown(ByVal sender _
      As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) _
      Handles drawWindow.MouseDown
      mPoints.Add(New Point(e.X, e.Y))
      drawWindow.Invalidate() " refresh panel
   End Sub " drawWindow_MouseDown
   Private Sub drawWindow_Paint(ByVal sender As Object, _
      ByVal e As System.Windows.Forms.PaintEventArgs) _
      Handles drawWindow.Paint
      Dim graphicsObject As Graphics = e.Graphics
      If mPoints.Count < 1 Then
         Return
      End If   
      
      Dim pointArray() As Point = mPoints.ToArray(mPoints(0).GetType())
      If polygonRadio.Checked Then 
         graphicsObject.DrawPolygon(mPen, pointArray)
      ElseIf lineRadio.Checked Then
         graphicsObject.DrawLines(mPen, pointArray)
      ElseIf filledPolygonRadio.Checked Then 
         graphicsObject.FillPolygon(mBrush, pointArray)
      End If

   End Sub 
   Private Sub cmdClear_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles cmdClear.Click
      mPoints.Clear()
      drawWindow.Invalidate()
   End Sub 
   Private Sub polygonRadio_CheckedChanged(ByVal sender As _
      System.Object, ByVal e As System.EventArgs) _
      Handles polygonRadio.CheckedChanged
      drawWindow.Invalidate()
   End Sub 
   Private Sub lineRadio_CheckedChanged(ByVal sender As _
      System.Object, ByVal e As System.EventArgs) _
      Handles lineRadio.CheckedChanged
      drawWindow.Invalidate()
   End Sub 
   
   Private Sub filledPolygonRadio_CheckedChanged(ByVal sender _
      As System.Object, ByVal e As System.EventArgs) _
      Handles filledPolygonRadio.CheckedChanged
      drawWindow.Invalidate() 
   End Sub 
   Private Sub cmdNewColor_Click(ByVal sender As _
      System.Object, ByVal e As System.EventArgs) _
      Handles cmdNewColor.Click
      Dim colorBox As ColorDialog = New ColorDialog()
      Dim result As DialogResult = colorBox.ShowDialog()
      If result = DialogResult.Cancel Then
         Return
      End If
      mPen.Color = colorBox.Color
      mBrush.Color = colorBox.Color 
      drawWindow.Invalidate() 
   End Sub 
End Class