Draw to the form indirectly through a bitmap : Paint Buffer « 2D Graphics « VB.Net Tutorial






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.CompilerServices.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.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.
    <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








17.76.Paint Buffer
17.76.1.Draw to the form indirectly through a bitmapDraw to the form indirectly through a bitmap
17.76.2.Use Bitmap to buffer paintUse Bitmap to buffer paint