广东 李玉君

  
一、条形码的读取
    用过键盘口式的扫条码工具的朋友就知道，它就如同在鍵盘上按下数字鍵一样，基本不需任何编程和处理。但如果你使用的是其它接口的话，可能你就要为该设备编写通讯代码了。以下有一段简单的25针串口的条码读取器通讯代码。
    Option Explicit
    Dim sData As String
    Private Sub Form_Load()
    With MSComm1
       .CommPort = 3 '设为COM3，试运行的系统而定，你可提供一个Combox让用户选择。
       .PortOpen = True　'打开通讯端口
    End With
    End Sub

    Private Sub MSComm1_OnComm()
        Dim EndPos As Integer
        Select Case MSComm1.CommEvent
        Case comEvReceive '当有数据传送过来时
            sData = sData & Trim(MSComm1.Input)
            '检索回车,通常读卡机每组数据結尾都返回一个回车作为结束符
             EndPos = InStr(1, sData, Chr(13))
             If EndPos = 0 Then '如果未结束就继续努力
             Else '读完一组。
             lblBarCode.Caption = sData '显示一组条形码
             With lstBarCode
                 .AddItem Mid(sData, 1, EndPos - 1) '添加一组条形码到列表
             End With
             sData = "" '清空
             End If
         End Select
    End Sub

    Private Sub cmdEnd_Click()
        MSComm1.PortOpen = False '关闭端口
        End
    End Sub
    
二、条形码的生成
    看完以上关于条码读取的代码是否觉得很容易呢？对，在VB上编程本来就不难。以下关于条形码生成的代码也是很容易理解，只需使用一个OFFICE的附带的BarCode控件就可以轻松打印出11种不同标准的条形码，足以满足我们的要求。想起我书架上的一本书中的一篇用Turbo C编写条形码打印程序文章，长篇大论，那时不知看了n天，打了n小时字结果也不尽人意，现在真是幸福多了:)。废话说完，得回归正题。且看条形码生成的代码及有关说明。
    源代码主要由两个窗体（frmMain主窗体和frmOption条码设置窗体）和两个模块组成(modGetScreen.bas、SysDLG32.bas)。考虑到篇幅，这里只列出部分较为关键的代码。
    新建一个标准工程，添加一个名为(Microsoft Access BarCode Control9)的条形码部件，并添加一个条码控件到窗口，并将窗口改名为frmMain，如图所示。由于控件比较多，这里不便细说，详细内容请看源代码。
    模块modGetScreen.bas代码如下：
    Option Explicit
    '声明BitBlt、GetDesktopWindow、GetWindowDC、ReleaseDC这几个API函数略
    Public RegUser As Boolean

    Sub GetObjImage1(Obj As Object, OwnerForm As PictureBox, Picture1 As PictureBox)
     'hDC
        Dim hWndDesk As Long
        Dim hDCDesk As Long
        '区域表达变量
        Dim x As Long
        Dim y As Long
        Dim w As Long
        Dim h As Long
        x = Obj.Left  Screen.TwipsPerPixelX
        y = Obj.Top  Screen.TwipsPerPixelY
        w = Obj.Width  Screen.TwipsPerPixelX
        h = Obj.Height  Screen.TwipsPerPixelY
        hDCDesk = OwnerForm.hdc
        '取出图像
        Call BitBlt(Picture1.hdc, 0, 0, w, h, hDCDesk, x, y, vbSrcCopy)
        Call ReleaseDC(hWndDesk, hDCDesk)
    End Sub

     
    主窗体frmMain.frm部分代码如下：
    Private Sub cmdPrint_Click()
    '生成条形码图像
        Dim r As Long, i As Integer, t As String,cfile As String '临时变量
        t = BarCode
        For i = 0 To Val(Times) - 1
            BarCode1.Value = BarCode + i
            DoEvents
            Picture1.Refresh
            GetObjImage1 BarCode1, Conel, Picture1
            If RegUser = False Then '如果未注册添加MASK标记
                Picture1.PaintPicture Picture2.Picture, 300, 300
            End If
            If Dir(SavePath, vbDirectory) = "" Then MkDir SavePath
            SavePath = SavePath & IIf(Right(SavePath, 1) <> "", "", "")
            cfile = SavePath & BarCode1.Value & ".bmp"
            SavePicture Picture1.Image, cfile '将条形码保存为图像文件以便打印
        Next
        BarCode = t
    End Sub

     
    条形码设置窗体frmOption.frm代码如下：
    Option Explicit
    '条形码设置模块

    Private Sub cboBig_Click()
        BarCode1.Style = cboBig.ListIndex '改变标准
    End Sub

    Private Sub cboDirection_Click()
        BarCode1.Direction = cboDirection.ListIndex '改变方向
    End Sub
    
    Private Sub cboLine_Click()
        BarCode1.LineWeight = cboLine.ListIndex '改变线宽
    End Sub

    Private Sub cboSmall_Click()
        BarCode1.SubStyle = cboSmall.ListIndex '改变样式
    End Sub

    Private Sub Check1_Click()
        BarCode1.ShowData = Check1.Value '是否显示数据
    End Sub

    Private Sub cmdChange_Click()
    '设置长、宽大小
        BarWidth = BarCode1.Height
        BarHeight = BarCode1.Width
        cmdRefresh_Click
    End Sub

    Private Sub cmdOK_Click()
    '传送条形码设定到主界面
    With frmMain.BarCode1
        .LineWeight = BarCode1.LineWeight
        .Style = BarCode1.Style
        .SubStyle = BarCode1.SubStyle
        .Direction = BarCode1.Direction
        .Width = BarCode1.Width
        .Height = BarCode1.Height
        .ShowData = BarCode1.ShowData
        Me.Hide
    End With
    With frmMain
        .Picture1.Width = .BarCode1.Width
        .Picture1.Height = .BarCode1.Height
        .Conel.Width = .BarCode1.Width
        .Conel.Height = .BarCode1.Height
    End With
    End Sub
     
    Private Sub cmdRefresh_Click()
        BarCode1.Width = BarWidth
        BarCode1.Height = BarHeight
    End Sub
     
    Private Sub Form_Load()
        LoadBarInfo
        BarWidth = BarCode1.Width
        BarHeight = BarCode1.Height
    End Sub

    Sub LoadBarInfo() '初始化选项
        LoadBigClass cboBig
        LoadSmallClass cboSmall
        LoadLineSize cboLine
        LoadDirection cboDirection
    End Sub


    Sub LoadBigClass(cbo As ComboBox) '条码标准
    With cbo
        .AddItem "UPC-A"
        .AddItem "UPC-E"
        .AddItem "EAN-13"
        .AddItem "EAN-8"
        .AddItem "Case Code"
        .AddItem "Codabar (NW-T)"
        .AddItem "Code-39"
        .AddItem "Code-128"
        .AddItem "U.S. Postnet"
        .AddItem "U.S. Postal FIM"
        .AddItem "JP Post"
        .ListIndex = 2
    End With
    End Sub


    Sub LoadSmallClass(cbo As ComboBox) '条码样式
    With cbo
        .AddItem "Standard"
        .AddItem "2-Digit Supplement"
        .AddItem "5-Digit Supplement"
        .AddItem "POS Case Code"
        .ListIndex = 0
    End With
    End Sub
　

　

许多人在编写数据库应用程序时，都想要加上条形码功能加强工作效率，尤其是销售管理，图书馆管理这类流量大的应用软件，但由于条形码技术难以掌握、标谁又多以及过去的技术种种原因，使得许多人望而却步。本文介绍的一套简单实用的条形码解决方法，希望能帮助各位完善软件系统的功能。文章源代码可以发信到peedy@shareware.com.cn索取。