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 Button1 As System.Windows.Forms.Button
    Friend WithEvents PictureBox1 As System.Windows.Forms.PictureBox
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    Friend WithEvents Button2 As System.Windows.Forms.Button
    Friend WithEvents SaveFileDialog1 As System.Windows.Forms.SaveFileDialog
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button
        Me.PictureBox1 = New System.Windows.Forms.PictureBox
        Me.Label1 = New System.Windows.Forms.Label
        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.Button2 = New System.Windows.Forms.Button
        Me.SaveFileDialog1 = New System.Windows.Forms.SaveFileDialog
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.BackColor = System.Drawing.Color.Silver
        Me.Button1.Location = New System.Drawing.Point(552, 88)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(120, 40)
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Go"
        '
        'PictureBox1
        '
        Me.PictureBox1.Location = New System.Drawing.Point(16, 16)
        Me.PictureBox1.Name = "PictureBox1"
        Me.PictureBox1.Size = New System.Drawing.Size(512, 512)
        Me.PictureBox1.TabIndex = 1
        Me.PictureBox1.TabStop = False
        '
        'Label1
        '
        Me.Label1.ForeColor = System.Drawing.Color.White
        Me.Label1.Location = New System.Drawing.Point(560, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(120, 32)
        Me.Label1.TabIndex = 2
        Me.Label1.Text = "Label1"
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(560, 152)
        Me.TextBox1.Multiline = True
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
        Me.TextBox1.Size = New System.Drawing.Size(184, 88)
        Me.TextBox1.TabIndex = 3
        Me.TextBox1.Text = "TextBox1"
        '
        'Button2
        '
        Me.Button2.BackColor = System.Drawing.Color.LightGray
        Me.Button2.Location = New System.Drawing.Point(560, 264)
        Me.Button2.Name = "Button2"
        Me.Button2.Size = New System.Drawing.Size(128, 40)
        Me.Button2.TabIndex = 4
        Me.Button2.Text = "Save Image"
        '
        'SaveFileDialog1
        '
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.BackColor = System.Drawing.Color.Black
        Me.ClientSize = New System.Drawing.Size(762, 580)
        Me.Controls.Add(Me.Button2)
        Me.Controls.Add(Me.TextBox1)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.PictureBox1)
        Me.Controls.Add(Me.Button1)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.Name = "Form1"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "Mandelbrot Image Generator"
        Me.ResumeLayout(False)

    End Sub

#End Region

    'Image is HEIGHT by WIDTH pixels
    Const IMAGE_HEIGHT As Integer = 512
    Const IMAGE_WIDTH As Integer = 512

    Const MAXITER As Integer = 1024
    'Dim mandelbrotBitmap As Bitmap = New Bitmap("red.bmp")
    'create a new 512x512 pixel bitmap to store the image
    Dim mandelbrotBitmap As Bitmap = New Bitmap(IMAGE_HEIGHT, IMAGE_WIDTH)

    'rectangle of the complex plane (may change by zooming)
    'Dim xmin As Double = -0.5
    'Dim xmax As Double = 0.5
    'Dim ymin As Double = 0.5
    'Dim ymax As Double = 1.5

    Dim xmin As Double = -2.0
    Dim xmax As Double = 2.0
    Dim ymin As Double = -2.0
    Dim ymax As Double = 2.0
    Dim xdiff, ydiff As Double
    'for user zoom rectangle
    Dim x1, x2, y1, y2 As Integer
    Dim new_xmin As Double = -2.0
    Dim new_xmax As Double = 2.0
    Dim new_ymin As Double = -2.0
    Dim new_ymax As Double = 2.0
    Dim isdragging As Boolean

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'mandelbrotBitmap.SetPixel(5, 5, Color.Aqua)
        'Dim p As Color() = mandelbrotBitmap.Palette.Entries()
        Dim i, j As Integer

        PictureBox1.Image = mandelbrotBitmap
        'mandelbrotBitmap.SetPixel(5, 5, Color.FromArgb(255, 255, 0, 0))
        'For i = 0 To 255
        '    For j = 0 To 255
        '        mandelbrotBitmap.SetPixel(i, j, Color.FromArgb(255, i, j, 0))
        '    Next j
        'Next i
        TextBox1.Text &= "(" & xmin & ", " & ymin & ") to (" & xmax & ", " & ymax & ")" & Chr(13) & Chr(10)

    End Sub

    Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        'Note: this method is called whenever the window becomes _dirty_ (needs to be redrawn)
        'Dim g As Graphics = e.Graphics
        'Dim myPen As Pen = New Pen(Color.White)
        'Dim myRectangle As Rectangle = New Rectangle(400, 400, 200, 200)
        'Dim rgn As Region = New Region(myRectangle)
        'g.DrawImage(mandelbrotBitmap, 0, 0)
        PictureBox1.Refresh()
        'g.DrawRectangle(myPen, myRectangle)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i, j, k As Integer
        Dim zRe, zIm, cRe, cIm As Double
        Dim zMagSquared As Double
        Dim zReNew, zImNew As Double
        Dim verticalStep, horizontalStep As Double

        xmin = new_xmin
        xmax = new_xmax
        ymin = new_ymin
        ymax = new_ymax

        xdiff = xmax - xmin
        ydiff = ymax - ymin
        verticalStep = ydiff / IMAGE_HEIGHT
        horizontalStep = xdiff / IMAGE_WIDTH

        'Note: 0, 0 on screen is in upper left corner, so
        'start at xmin, ymax for mandelbrotBitmap(0,0)
        For i = 0 To IMAGE_HEIGHT - 1 'i is row number
            cIm = ymax - i * verticalStep 'filling bitmap top to bottom
            For j = 0 To IMAGE_WIDTH - 1
                cRe = xmin + j * horizontalStep 'filling left to right
                zRe = 0.0
                zIm = 0.0
                'now start iteration: z_i+1 = (z_i)^2 + c
                For k = 1 To MAXITER - 1
                    zReNew = zRe ^ 2 - zIm ^ 2 + cRe
                    zImNew = 2 * zRe * zIm + cIm
                    zRe = zReNew
                    zIm = zImNew
                    zMagSquared = zRe ^ 2 + zIm ^ 2
                    If zMagSquared > 4 Then Exit For
                Next k
                If k = MAXITER Then
                    'k = 0
                    mandelbrotBitmap.SetPixel(j, i, Color.FromArgb(255, 0, 255, 255))
                Else
                    mandelbrotBitmap.SetPixel(j, i, Color.FromArgb(255, k Mod 256, 0, 16 * (k Mod 16)))
                End If
                'TextBox2.Text = TextBox2.Text & k & Chr(9)
            Next j
            Me.Refresh()
            'TextBox2.Text = TextBox2.Text & Chr(13) & Chr(10)
        Next i
    End Sub

    Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click

    End Sub

    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        isDragging = True
        X1 = e.X
        Y1 = e.Y
    End Sub

    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        Dim tmp, old_xmin, old_xmax, old_ymin, old_ymax As Integer
        isDragging = False
        X2 = e.X
        Y2 = e.Y
        If (X2 < X1) Then
            tmp = x1
            x1 = x2
            x2 = tmp
        End If
        If (Y2 < Y1) Then
            tmp = y1
            Y1 = Y2
            Y2 = tmp
        End If
        'preserve aspect ratio
        y2 = y1 + IMAGE_HEIGHT / IMAGE_WIDTH * (x2 - x1)
        TextBox1.Text &= "x1= " & x1 & " Y1= " & y1 & " X2= " & x2 & " Y2= " & y2 & Chr(13) & Chr(10)


        'reset (xmin, ymin) and (xmax, ymax)
        new_xmin = xmin + xdiff * (x1 / IMAGE_WIDTH)
        new_xmax = xmin + xdiff * (x2 / IMAGE_WIDTH)
        new_ymin = ymax - ydiff * (y2 / IMAGE_HEIGHT)
        new_ymax = ymax - ydiff * (y1 / IMAGE_HEIGHT)

        TextBox1.Text &= "(" & new_xmin & ", " & new_ymin & ") to (" & new_xmax & ", " & new_ymax & ")" & Chr(13) & Chr(10)
    End Sub

    Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        Label1.Text = "(" & e.X & ", " & e.Y & ")"
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        mandelbrotBitmap.Save("kgj.bmp")
    End Sub

    Private Sub SaveFileDialog1_FileOk(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles SaveFileDialog1.FileOk

    End Sub
End Class