VB.Net Tutorial/2D Graphics/Paint Buffer

Draw to the form indirectly through a bitmap

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
public class DrawImageIndirectly
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object, _
          ByVal e As System.Windows.Forms.PaintEventArgs) _
          Handles Me.Paint
        
        Dim x As Single
        Dim y As Single
        Dim xCenter As Single
        Dim yCenter As Single
        Dim angle As Single
        Dim radians As Single
        Dim workImage As Bitmap
        Dim canvas As Graphics
        workImage = New Bitmap(Me.Size.Width, Me.Size.Height,e.Graphics)
        canvas = Graphics.FromImage(workImage)
        For angle = 0 To 360 Step 2
            radians = angle * Math.PI / 180
            x = 500 * Math.Cos(radians)
            y = 500 * Math.Sin(radians)
            yCenter = Me.ClientSize.Height / 2
            xCenter = Me.ClientSize.Width * 10 / 21
            canvas.DrawLine(Pens.Black, xCenter, yCenter, xCenter + x, yCenter + y)
            xCenter = Me.ClientSize.Width * 11 / 21
            canvas.DrawLine(Pens.Black, xCenter, yCenter, xCenter + x, yCenter + y)
        Next angle
        e.Graphics.DrawImage(workImage, 0, 0)
    End Sub
    Private Sub Form1_Resize(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Resize
        Me.Invalidate()
    End Sub
End Class

<Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _
Partial Class Form1
    Inherits System.Windows.Forms.Form
    "Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub
    "Required by the Windows Form Designer
    Private components As System.ruponentModel.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.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.SuspendLayout()
        "
        "Form1
        "
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(430, 419)
        Me.DoubleBuffered = True
        Me.Name = "Form1"
        Me.Text = "Creating a Bitmap"
        Me.ResumeLayout(False)
    End Sub
End Class

Use Bitmap to buffer paint

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
Imports System.Math
Imports System.Drawing.Imaging

public class Bufferring
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class
Public Class Form1
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
     Handles MyBase.Load
        DrawDiamond()
    End Sub
    Private Sub Form1_Resize(ByVal sender As Object, ByVal e As System.EventArgs) _
     Handles MyBase.Resize
        DrawDiamond()
    End Sub
    Private Sub DrawDiamond()
        Dim wid As Integer = picCanvas.ClientSize.Width
        Dim hgt As Integer = picCanvas.ClientSize.Height
        If wid < 1 Or hgt < 1 Then Exit Sub
        Dim bm As New Bitmap(wid, hgt)
        Dim gr As Graphics = Graphics.FromImage(bm)
        Dim bg_brush As New HatchBrush(HatchStyle.HorizontalBrick, Color.Blue, Color.Aqua)
        gr.FillRectangle(bg_brush, picCanvas.ClientRectangle)
        Dim pts() As Point = {New Point(wid \ 2, 0),New Point(wid, hgt \ 2), _
            New Point(wid \ 2, hgt),New Point(0, hgt \ 2) }
        gr.FillPolygon(Brushes.White, pts)
        gr.DrawPolygon(Pens.Black, pts)
        picCanvas.Image = bm
        bg_brush.Dispose()
        gr.Dispose()
    End Sub
End Class

<Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form
    "Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub
    "Required by the Windows Form Designer
    Private components As System.ruponentModel.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.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.picCanvas = New System.Windows.Forms.PictureBox
        CType(Me.picCanvas, System.ruponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        "
        "picCanvas
        "
        Me.picCanvas.Dock = System.Windows.Forms.DockStyle.Fill
        Me.picCanvas.Location = New System.Drawing.Point(0, 0)
        Me.picCanvas.Name = "picCanvas"
        Me.picCanvas.Size = New System.Drawing.Size(292, 273)
        Me.picCanvas.TabIndex = 0
        Me.picCanvas.TabStop = False
        "
        "Form1
        "
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.picCanvas)
        Me.Name = "Form1"
        Me.Text = "AutoRedraw"
        CType(Me.picCanvas, System.ruponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)
    End Sub
    Friend WithEvents picCanvas As System.Windows.Forms.PictureBox
End Class