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.Runtime.InteropServices

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 MainMenu1 As System.Windows.Forms.MainMenu
    Friend WithEvents line As System.Windows.Forms.MenuItem
    Friend WithEvents MenuItem1 As System.Windows.Forms.MenuItem
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.MainMenu1 = New System.Windows.Forms.MainMenu()
        Me.line = New System.Windows.Forms.MenuItem()
        Me.MenuItem1 = New System.Windows.Forms.MenuItem()
        '
        'MainMenu1
        '
        Me.MainMenu1.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.line, Me.MenuItem1})
        '
        'line
        '
        Me.line.Index = 0
        Me.line.Text = "画直线段"
        '
        'MenuItem1
        '
        Me.MenuItem1.Index = 1
        Me.MenuItem1.Text = "拾取"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.BackColor = System.Drawing.Color.White
        Me.ClientSize = New System.Drawing.Size(440, 366)
        Me.Menu = Me.MainMenu1
        Me.Name = "Form1"
        Me.Text = "Form1"

    End Sub

#End Region

    <DllImport("gdi32.dll")> _
     Private Shared Function SetROP2(ByVal hdc As IntPtr, _
         ByVal nDrawMode As Integer) As Boolean
    End Function

    <DllImport("gdi32.dll")> _
    Private Shared Function Rectangle _
        (ByVal hdc As IntPtr, ByVal X1 As Integer, ByVal Y1 As Integer, _
        ByVal X2 As Integer, ByVal Y2 As Integer) As Boolean
    End Function

    Private m_StartX, m_StartY As Single
    Private m_EndX, m_EndY As Single
    Private m_Step As Integer = 0

    Protected Overrides Sub OnMouseDown(ByVal e As Windows.Forms.MouseEventArgs)
        Dim g As Graphics = Me.CreateGraphics()
        Dim hdc As IntPtr = g.GetHdc()
        m_Step += 1
        SetROP2(hdc, 10)
        If m_Step = 1 Then
            m_StartX = e.X
            m_StartY = e.Y
            m_EndX = e.X
            m_EndY = e.Y
        ElseIf m_Step = 2 Then
            Rectangle(hdc, m_StartX, m_StartY, m_EndX, m_EndY)
            Rectangle(hdc, m_StartX, m_StartY, e.X, e.Y)
            m_Step = 0
        End If
        g.ReleaseHdc(hdc)
    End Sub

    Protected Overrides Sub OnMouseMove(ByVal e As Windows.Forms.MouseEventArgs)
        Dim g As Graphics = Me.CreateGraphics()
        Dim prex As Single, prey As Single
        If m_Step = 1 Then
            Dim hdc As IntPtr = g.GetHdc()
            prex = m_EndX
            prey = m_EndY
            SetROP2(hdc, 10)
            Rectangle(hdc, m_StartX, m_StartY, prex, prey)
            Rectangle(hdc, m_StartX, m_StartY, e.X, e.Y)
            m_EndX = e.X
            m_EndY = e.Y
            g.ReleaseHdc(hdc)
        End If
    End Sub

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

End Class