使用WPF动态生成Code 39条形码

最近在看些条形码方面相关的资料，而如果只是看的话，效果似乎并不怎么好，所以决定动手做点Demo，以增强对相关知识的记忆。

这里是一个我编写的使用WPF生成Code 39的例子，Code 39的编码很简单，故而第一次先用它做为尝试。

标准的Code 39只支持43个字符，0~9，A~Z，-，.，$， /， +， %以及空格。除此之外，*用于起始和终止符号。而通过使用两个编码符的扩展，则可以支持所有的Acsii码字符。相关知识可以在维基百科上找到。

由于是WPF，Demo分为两个文件，xaml文件包含界面布局相关的代码：

     <Window x:Class="Code39Demo.MainWindow"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded">
         <Grid>
             <Grid.RowDefinitions>
                 <RowDefinition></RowDefinition>
                 <RowDefinition></RowDefinition>
             </Grid.RowDefinitions>
             <TextBox Name="Textbox1" VerticalContentAlignment="Center" TextChanged="Textbox1_TextChanged"></TextBox>
             <Canvas Name="Canvas1" Grid.Row="1"></Canvas>
         </Grid>
     </Window>  

xaml.cs文件是具体的实现，主要功能是在文本框内容改变的时候动态构成Code 39条形码：

     using System.Collections.Generic;
     using System.Text;
     using System.Text.RegularExpressions;
     using System.Windows;
     using System.Windows.Controls;
     using System.Windows.Media;
     using System.Windows.Shapes;  

     namespace Code39Demo
     {
         /// <summary>
         /// Interaction logic for MainWindow.xaml
         /// </summary>
         public partial class MainWindow : Window
         {
             public MainWindow()
             {
                 InitializeComponent();
             }  

             private void Window_Loaded(object sender, RoutedEventArgs e)
             {
                 Textbox1.Focus();
             }  

             private void Textbox1_TextChanged(object sender, TextChangedEventArgs e)
             {
                 Canvas1.Children.Clear();  

                 TextBox textBox = e.Source as TextBox;
                 if (textBox != null)
                 {
                     string content = textBox.Text;
                     if (string.IsNullOrEmpty(content))
                     {
                         textBox.BorderBrush = null;
                         return;
                     }  

                     string code = string.Empty;
                     bool result = TryConvertCode(content, out code);
                     if (!result)
                     {
                         textBox.BorderBrush = new SolidColorBrush(Colors.Red);
                         textBox.BorderThickness = new Thickness();
                         return;
                     }
                     else
                     {
                         textBox.BorderBrush = null;
                     }  

                     int thinWidth = ;
                     int thickWidth =  * thinWidth;
                     int currentPos = ;  

                     for (int i = ; i < code.Length; i++)
                     {
                         Rectangle r = new Rectangle();
                         r.Height = ;  

                         Canvas.SetLeft(r, currentPos);  

                         switch (code[i])
                         {
                             case 'N':
                                 {
                                     r.Fill = new SolidColorBrush(Colors.Black);
                                     currentPos += thinWidth;
                                     r.Width = thinWidth;
                                     break;
                                 }
                             case 'n':
                                 {
                                     r.Fill = new SolidColorBrush(Colors.White);
                                     currentPos += thinWidth;
                                     r.Width = thinWidth;
                                     break;
                                 }
                             case 'W':
                                 {
                                     r.Fill = new SolidColorBrush(Colors.Black);
                                     currentPos += thickWidth;
                                     r.Width = thickWidth;
                                     break;
                                 }
                             case 'w':
                                 {
                                     r.Fill = new SolidColorBrush(Colors.White);
                                     currentPos += thickWidth;
                                     r.Width = thickWidth;
                                     break;
                                 }
                         }  

                         Canvas1.Children.Add(r);
                     }
                 }
             }  

             private bool TryConvertCode(string content, out string code)
             {
                 code = string.Empty;
                 string c = "*" + content + "*";
                 StringBuilder sb = new StringBuilder();  

                 for (int i = ; i < c.Length; i++)
                 {
                     string value = string.Empty;
                     bool result = _code39Map.TryGetValue(c[i], out value);
                     if (!result)
                     {
                         return false;
                     }  

                     sb.Append(value);
                     sb.Append('n');
                 }  

                 code = sb.Remove(sb.Length - , ).ToString();  

                 return true;
             }  

             private static Dictionary<char, string> _code39Map = new Dictionary<char, string>();  

             static MainWindow()
             {
                 _code39Map[''] = "NnNwWnWnN";
                 _code39Map[''] = "WnNwNnNnW";
                 _code39Map[''] = "NnWwNnNnW";
                 _code39Map[''] = "WnWwNnNnN";
                 _code39Map[''] = "NnNwWnNnW";
                 _code39Map[''] = "WnNwWnNnN";
                 _code39Map[''] = "NnWwWnNnN";
                 _code39Map[''] = "NnNwNnWnW";
                 _code39Map[''] = "WnNwNnWnN";
                 _code39Map[''] = "NnWwNnWnN";  

                 _code39Map['A'] = "WnNnNwNnW";
                 _code39Map['B'] = "NnWnNwNnW";
                 _code39Map['C'] = "WnWnNwNnN";
                 _code39Map['D'] = "NnNnWwNnW";
                 _code39Map['E'] = "WnNnWwNnN";
                 _code39Map['F'] = "NnWnWwNnN";
                 _code39Map['G'] = "NnNnNwWnW";
                 _code39Map['H'] = "WnNnNwWnN";
                 _code39Map['I'] = "NnWnNwWnN";
                 _code39Map['J'] = "NnNnWwWnN";
                 _code39Map['K'] = "WnNnNnNwW";
                 _code39Map['L'] = "NnWnNnNwW";
                 _code39Map['M'] = "WnWnNnNwN";
                 _code39Map['N'] = "NnNnWnNwW";
                 _code39Map['O'] = "WnNnWnNwN";
                 _code39Map['P'] = "NnWnWnNwN";
                 _code39Map['Q'] = "NnNnNnWwW";
                 _code39Map['R'] = "WnNnNnWwN";
                 _code39Map['S'] = "NnWnNnWwN";
                 _code39Map['T'] = "NnNnWnWwN";
                 _code39Map['U'] = "WwNnNnNnW";
                 _code39Map['V'] = "NwWnNnNnW";
                 _code39Map['W'] = "WwWnNnNnN";
                 _code39Map['X'] = "NwNnWnNnW";
                 _code39Map['Y'] = "WwNnWnNnN";
                 _code39Map['Z'] = "NwWnWnNnN";  

                 _code39Map['-'] = "NwNnNnWnW";
                 _code39Map['.'] = "NwNnNnWnW";
                 _code39Map[' '] = "NwWnNnWnN";
                 _code39Map['$'] = "NwNwNwNnN";
                 _code39Map['/'] = "NwNwNnNwN";
                 _code39Map['+'] = "NwNnNwNwN";
                 _code39Map['%'] = "NnNwNwNwN";  

                 _code39Map['*'] = "NwNnWnWnN";
             }
         }
     }  

各字符对应编码中，W表示黑色宽条，w表示白色宽条，N表示黑色窄条，n表示白色窄条。需要注意的是，Code 39的相邻字符间需要有一个白色窄条用于分隔。

这个Demo还欠缺Code 39中校验码的处理（通常不需要），如果有需要的话，可以在此基础上补充，相信并不是困难的工作。

原文同步发布于我的个人博客