' 导入命名空间
Imports System.Drawing
Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private WithEvents trackBar1 As System.Windows.Forms.TrackBar
    Private textBox1 As System.Windows.Forms.TextBox

    <System.STAThread()> _
    Public Shared Sub Main()
        System.Windows.Forms.Application.Run(New Form1)
    End Sub

    Public Sub New()
        Me.textBox1 = New System.Windows.Forms.TextBox
        Me.trackBar1 = New System.Windows.Forms.TrackBar

        ' TextBox for TrackBar.Value update.
        Me.textBox1.Location = New System.Drawing.Point(240, 16)
        Me.textBox1.Size = New System.Drawing.Size(48, 20)

        ' Set up how the form should be displayed and add the controls to the form.
        Me.ClientSize = New System.Drawing.Size(296, 62)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.textBox1, Me.trackBar1})
        Me.Text = "TrackBar Example"

        ' Set up the TrackBar.
        Me.trackBar1.Location = New System.Drawing.Point(8, 8)
        Me.trackBar1.Size = New System.Drawing.Size(224, 45)

        ' The Maximum property sets the value of the track bar when
        ' the slider is all the way to the right.
        trackBar1.Maximum = 30

        ' The TickFrequency property establishes how many positions
        ' are between each tick-mark.
        trackBar1.TickFrequency = 5

        ' The LargeChange property sets how many positions to move
        ' if the bar is clicked on either side of the slider.
        trackBar1.LargeChange = 3

        ' The SmallChange property sets how many positions to move
        ' if the keyboard arrows are used to move the slider.
        trackBar1.SmallChange = 2
    End Sub

    Private Sub trackBar1_Scroll(ByVal sender As Object, _
                    ByVal e As System.EventArgs) Handles trackBar1.Scroll

        ' Display the trackbar value in the text box.
        textBox1.Text = trackBar1.Value
    End Sub 

End Class

' 导入命名空间
Imports System.Collections
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms

public class DrawCurveTension
   public Shared Sub Main
        Application.Run(New Form1)
   End Sub
End class

Public Class Form1
    Private BendPoints As New Generic.List(Of Point)

    Private Sub Form1_MouseClick(ByVal sender As Object,ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseClick
        BendPoints.Add(New Point(e.X, e.Y))
        Me.Refresh()
    End Sub

    Private Sub Form1_Paint(ByVal sender As Object, _
          ByVal e As System.Windows.Forms.PaintEventArgs) _
          Handles Me.Paint

        Dim tension As Single
        Dim canvas As Graphics
        Dim scanPoint As Point
        Const PointSize As Integer = 2

        tension = TensionLevel.Value / TensionLevel.Maximum
        LabelTension.Text = "Tension:  " & tension.ToString

        canvas = e.Graphics
        For Each scanPoint In BendPoints
            canvas.FillEllipse(Brushes.Red,scanPoint.X - PointSize,scanPoint.Y - PointSize,PointSize * 2, PointSize * 2)
        Next scanPoint

        If (BendPoints.Count > 1) Then
            canvas.DrawCurve(Pens.Black, BendPoints.ToArray, tension)
        End If
    End Sub

    Private Sub TensionLevel_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) _
          Handles TensionLevel.ValueChanged
        Me.Refresh()
    End Sub

    Private Sub ActReset_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles ActReset.Click
        BendPoints.Clear()
        Me.Refresh()
    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.LabelTension = New System.Windows.Forms.Label
        Me.TensionLevel = New System.Windows.Forms.TrackBar
        Me.ActReset = New System.Windows.Forms.Button
        CType(Me.TensionLevel, System.ComponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        '
        'LabelTension
        '
        Me.LabelTension.AutoSize = True
        Me.LabelTension.Location = New System.Drawing.Point(24, 32)
        Me.LabelTension.Name = "LabelTension"
        Me.LabelTension.Size = New System.Drawing.Size(66, 13)
        Me.LabelTension.TabIndex = 0
        Me.LabelTension.Text = "Tension: 0.0"
        '
        'TensionLevel
        '
        Me.TensionLevel.Location = New System.Drawing.Point(136, 24)
        Me.TensionLevel.Name = "TensionLevel"
        Me.TensionLevel.Size = New System.Drawing.Size(224, 45)
        Me.TensionLevel.TabIndex = 1
        '
        'ActReset
        '
        Me.ActReset.Location = New System.Drawing.Point(392, 24)
        Me.ActReset.Name = "ActReset"
        Me.ActReset.Size = New System.Drawing.Size(75, 23)
        Me.ActReset.TabIndex = 2
        Me.ActReset.Text = "Reset"
        Me.ActReset.UseVisualStyleBackColor = True
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(547, 264)
        Me.Controls.Add(Me.ActReset)
        Me.Controls.Add(Me.TensionLevel)
        Me.Controls.Add(Me.LabelTension)
        Me.Name = "Form1"
        Me.Text = "Drawing Cardinal Splines"
        CType(Me.TensionLevel, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub
    Friend WithEvents LabelTension As System.Windows.Forms.Label
    Friend WithEvents TensionLevel As System.Windows.Forms.TrackBar
    Friend WithEvents ActReset As System.Windows.Forms.Button

End Class