form1.vb

苏金明编写的《用VB.NET和VC#.NET开发交互式CAD系统》一书的源代码

Imports System.Drawing.Drawing2D

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

    Public Sub New()
        MyBase.New()

        '该调用是 Windows 窗体设计器所必需的。
        InitializeComponent()

        '在 InitializeComponent() 调用之后添加任何初始化

    End Sub

    '窗体重写处置以清理组件列表。
    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

    'Windows 窗体设计器所必需的
    Private components As System.ComponentModel.IContainer

    '注意：以下过程是 Windows 窗体设计器所必需的
    '可以使用 Windows 窗体设计器修改此过程。
    '不要使用代码编辑器修改它。
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.TextBox1 = New System.Windows.Forms.TextBox()
        Me.SuspendLayout()
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(8, 8)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(96, 21)
        Me.TextBox1.TabIndex = 0
        Me.TextBox1.Text = ""
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.TextBox1})
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region


    Protected Overrides Sub OnPaint(ByVal e As Windows.Forms.PaintEventArgs)
        '本程序建立Ｘ轴正向向右，Ｙ轴正向向上，原点在屏幕中心的全局坐标系
        '使Ｙ轴朝上，需要作相对于Ｘ轴的镜像，变换矩阵为［1,0,0,-1,0,0］
        Dim g As Graphics = e.Graphics
        g.FillRectangle(Brushes.White, Me.ClientRectangle)
        g.DrawEllipse(Pens.Black, -100, -100, 200, 200)

        '相对于Ｘ轴进行镜像变换
        Dim mat As New Matrix(1, 0, 0, -1, 0, 0)
        g.Transform = mat
        Dim rect As Rectangle = Me.ClientRectangle
        Dim w As Integer = rect.Width
        Dim h As Integer = rect.Height
        '将原点移到屏幕中心
        g.TranslateTransform(w / 2, -h / 2)

        '以原点为中心，绘一个半径为１００的圆
        '注意：由于相对于Ｘ轴作了镜像变换，所有与上下有关的
        '　　　绘图参数都交换了方向，如左上角变成了左下角
        g.DrawEllipse(Pens.Red, -100, -100, 200, 200)

        g.TranslateTransform(100, 100)
        g.DrawEllipse(Pens.Green, -100, -100, 200, 200)

        g.ScaleTransform(2, 2)
        g.DrawEllipse(Pens.Blue, -100, -100, 200, 200)

    End Sub

    Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As Windows.Forms.MouseEventArgs) Handles MyBase.MouseMove
        '在文本框中显示当前点的坐标。屏幕坐标被转换为工作区坐标
        Dim g As Graphics = CreateGraphics()
        Dim rect As Rectangle = Me.ClientRectangle
        Dim w As Integer = rect.Width
        Dim h As Integer = rect.Height
        TextBox1.Text = " "
        TextBox1.Text = Str(e.X - w / 2) & "  " & Str(-(e.Y - h / 2))
    End Sub

End Class