drawer.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

Public Class Drawer
    Inherits Visitor

    Private m_Style, m_Width, m_Color, aDStyle, aWidth As Integer
    Private aPen, oldP, aColor As Long

    Public Sub preDraw(ByVal hdc As IntPtr)
        '设置画笔参数
        Win32API.SetROP2(hdc, 13)
        m_Style = 0
        m_Width = 3
        m_Color = RGB(255, 0, 0)
        '创建画笔
        aPen = Win32API.CreatePen(m_Style, m_Width, m_Color)
        '把画笔选入绘图环境，并返回原来的画笔
        oldP = Win32API.SelectObject(hdc, aPen)
    End Sub

    Public Sub postDraw(ByVal g As Graphics, ByVal hdc As IntPtr)
        '把原来的画笔选入绘图环境
        Win32API.SelectObject(hdc, oldP)
        '删除新创建的画笔
        Win32API.DeleteObject(aPen)
        '释放绘图环境句柄
        g.ReleaseHdc(hdc)
    End Sub

    Public Overloads Overrides Sub toDraw(ByVal g As Graphics, ByVal line As CLine)
        Dim hdc As IntPtr = g.GetHdc
        preDraw(hdc)
        '把画笔移动到直线段的起点处
        Win32API.MoveToEx(hdc, 50, 50, Nothing)
        '绘直线段到终点
        Win32API.LineTo(hdc, 200, 200)
        postDraw(g, hdc)
    End Sub

    Public Overloads Overrides Sub toDraw(ByVal g As Graphics, ByVal circle As CCircle)
        Dim hdc As IntPtr = g.GetHdc
        preDraw(hdc)
        '把空刷子选入绘图环境
        Win32API.SelectObject(hdc, Win32API.GetStockObject(5))
        '绘圆
        Win32API.Ellipse(hdc, 100, 80, 300, 400)
        postDraw(g, hdc)
    End Sub

End Class