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。
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Name = "Form1"
        Me.Text = "圆整错误"

    End Sub

#End Region


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

        '整型坐标下的端点
        Dim p1 As New Point(1, 1)
        Dim p2 As New Point(11, 20)
        '浮点坐标下的端点
        Dim p3 As New PointF(1, 1)
        Dim p4 As New PointF(11, 20)

        '求以前两点为端点的直线段的中点
        '整形坐标下的中点
        Dim pMiddle1 As New Point((p1.X + p2.X) / 2, (p1.Y + p2.Y) / 2)
        '浮点坐标下的中点
        Dim pMiddle2 As New PointF((p3.X + p4.X) / 2, (p3.Y + p4.Y) / 2)

        '放大15倍显示
        g.ScaleTransform(15, 15)
        Dim pen1 As Pen = New Pen(Color.Black)
        Dim pen2 As Pen = New Pen(Color.Red)
        '放大后笔宽也放大了，除以放大倍数，保持原宽
        pen1.Width = pen1.Width / 15
        pen2.Width = pen2.Width / 15
        '整型坐标下直接绘制整条直线段
        g.DrawLine(pen1, p1, p2)
        '整型坐标下用虚线分别把直线段的端点与整型坐标下得到的中点相连
        pen2.DashStyle = DashStyle.Dash
        g.DrawLine(pen2, p1, pMiddle1)
        g.DrawLine(pen2, pMiddle1, p2)
        '右移
        g.TranslateTransform(10, 0)
        '浮点坐标下直接绘制整条直线段
        g.DrawLine(pen1, p3, p4)
        '浮点坐标下用虚线分别把直线段的端点与整型坐标下得到的中点相连
        pen2.DashStyle = DashStyle.Dash
        g.DrawLine(pen2, p3, pMiddle2)
        g.DrawLine(pen2, pMiddle2, p4)

        pen1.Dispose()
        pen2.Dispose()

    End Sub
End Class