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

    Private m_preBegin, m_preEnd As PointF
    Private m_curBegin, m_curEnd As PointF


#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。
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        components = New System.ComponentModel.Container()
        Me.Text = "Form1"
    End Sub

#End Region

    Private Sub Draw(ByVal g As Graphics)
        g.DrawEllipse(Pens.Blue, 50, 50, 200, 200)
        g.DrawLine(Pens.Blue, 40, 80, 300, 200)
    End Sub

    Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        Dim g As Graphics = e.Graphics
        g.FillRectangle(Brushes.White, Me.ClientRectangle)
        Draw(g)
    End Sub

    Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles MyBase.MouseMove
        Dim g As Graphics = Me.CreateGraphics()
        Draw(g)

        m_curBegin = New PointF(e.X - 5, e.Y - 5)
        m_curEnd = New PointF(e.X + 5, e.Y + 5)
        g.DrawRectangle(Pens.White, m_preBegin.X, _
               m_preBegin.Y, 10, 10)
        g.DrawRectangle(Pens.Green, m_curBegin.X, _
               m_curBegin.Y, 10, 10)

        '把拾取矩形转换为四条直线段
        Dim line1 As CLine() = {Nothing, Nothing, Nothing, Nothing}
        line1(0) = New CLine(m_curBegin, New PointF(m_curBegin.X, m_curEnd.Y))
        line1(1) = New CLine(New PointF(m_curBegin.X, m_curEnd.Y), m_curEnd)
        line1(2) = New CLine(m_curEnd, New PointF(m_curEnd.X, m_curBegin.Y))
        line1(3) = New CLine(New PointF(m_curEnd.X, m_curBegin.Y), m_curBegin)

        Dim pickPen As New Pen(Color.Red)
        pickPen.DashStyle = DashStyle.Dash

        Dim i As Integer
        '拾取直线段
        For i = 0 To 3
            Dim newline As New CLine(New PointF(40, 80), New PointF(300, 200))
            Dim inter1 As Single()

            inter1 = LineLine(line1(i), newline)
            If inter1(0) > 0 Then
                newline.Draw(g, Pens.White)
                newline.Draw(g, pickPen)
            End If
        Next

        '拾取圆
        For i = 0 To 3
            Dim circle As New CCircle(New PointF(150, 150), New PointF(150, 50))
            Dim inter3 As Single()
            inter3 = LineCircle(line1(i), circle)
            If inter3(0) > 0 Then
                circle.Draw(g, Pens.White)
                circle.Draw(g, pickPen)
            End If
        Next i

        m_preBegin = m_curBegin
        m_preEnd = m_curEnd

    End Sub
End Class