本文介绍了如何生成code39吧codeS在vb.net的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想从我的应用程序中创建code39连接codeD吧codeS。
I want to create Code39 encoded barcodes from my application.
我知道我可以使用的字体，但我倒是preFER不是因为我必须注册在服务器上的字体和我有一些pretty的不好的经验这一点。
I know I can use a font for this, but I'd prefer not to as I'd have to register the font on the server and I've had some pretty bad experiences with that.
是我提出这个问题后，已经产生的一个例子是，在答案的
推荐答案
这是我目前的codebehind，有很多的评论：
This is my current codebehind, with lots of comments:
Option Explicit On
Option Strict On
Imports System.Drawing
Imports System.Drawing.Imaging
Imports System.Drawing.Bitmap
Imports System.Drawing.Graphics
Imports System.IO
Partial Public Class Barcode
Inherits System.Web.UI.Page
'Sebastiaan Janssen - 20081001 - TINT-30584
'Most of the code is based on this example:
'http://www.atalasoft.com/cs/blogs/loufranco/archive/2008/04/25/writing-code-39-barcodes-with-javascript.aspx-generation.aspx
'With a bit of this thrown in:
'http://www.atalasoft.com/cs/blogs/loufranco/archive/2008/03/24/code-39-barcode
Private _encoding As Hashtable = New Hashtable
Private Const _wideBarWidth As Short = 8
Private Const _narrowBarWidth As Short = 2
Private Const _barHeight As Short = 100
Sub BarcodeCode39()
_encoding.Add("*", "bWbwBwBwb")
_encoding.Add("-", "bWbwbwBwB")
_encoding.Add("$", "bWbWbWbwb")
_encoding.Add("%", "bwbWbWbWb")
_encoding.Add(" ", "bWBwbwBwb")
_encoding.Add(".", "BWbwbwBwb")
_encoding.Add("/", "bWbWbwbWb")
_encoding.Add("+", "bWbwbWbWb")
_encoding.Add("0", "bwbWBwBwb")
_encoding.Add("1", "BwbWbwbwB")
_encoding.Add("2", "bwBWbwbwB")
_encoding.Add("3", "BwBWbwbwb")
_encoding.Add("4", "bwbWBwbwB")
_encoding.Add("5", "BwbWBwbwb")
_encoding.Add("6", "bwBWBwbwb")
_encoding.Add("7", "bwbWbwBwB")
_encoding.Add("8", "BwbWbwBwb")
_encoding.Add("9", "bwBWbwBwb")
_encoding.Add("A", "BwbwbWbwB")
_encoding.Add("B", "bwBwbWbwB")
_encoding.Add("C", "BwBwbWbwb")
_encoding.Add("D", "bwbwBWbwB")
_encoding.Add("E", "BwbwBWbwb")
_encoding.Add("F", "bwBwBWbwb")
_encoding.Add("G", "bwbwbWBwB")
_encoding.Add("H", "BwbwbWBwb")
_encoding.Add("I", "bwBwbWBwb")
_encoding.Add("J", "bwbwBWBwb")
_encoding.Add("K", "BwbwbwbWB")
_encoding.Add("L", "bwBwbwbWB")
_encoding.Add("M", "BwBwbwbWb")
_encoding.Add("N", "bwbwBwbWB")
_encoding.Add("O", "BwbwBwbWb")
_encoding.Add("P", "bwBwBwbWb")
_encoding.Add("Q", "bwbwbwBWB")
_encoding.Add("R", "BwbwbwBWb")
_encoding.Add("S", "bwBwbwBWb")
_encoding.Add("T", "bwbwBwBWb")
_encoding.Add("U", "BWbwbwbwB")
_encoding.Add("V", "bWBwbwbwB")
_encoding.Add("W", "BWBwbwbwb")
_encoding.Add("X", "bWbwBwbwB")
_encoding.Add("Y", "BWbwBwbwb")
_encoding.Add("Z", "bWBwBwbwb")
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
BarcodeCode39()
Dim barcode As String = String.Empty
If Not IsNothing(Request("barcode")) AndAlso Not (Request("barcode").Length = 0) Then
barcode = Request("barcode")
Response.ContentType = "image/png"
Response.AddHeader("Content-Disposition", String.Format("attachment; filename=barcode_{0}.png", barcode))
'TODO: Depending on the length of the string, determine how wide the image will be
GenerateBarcodeImage(250, 140, barcode).WriteTo(Response.OutputStream)
End If
End Sub
Protected Function getBCSymbolColor(ByVal symbol As String) As System.Drawing.Brush
getBCSymbolColor = Brushes.Black
If symbol = "W" Or symbol = "w" Then
getBCSymbolColor = Brushes.White
End If
End Function
Protected Function getBCSymbolWidth(ByVal symbol As String) As Short
getBCSymbolWidth = _narrowBarWidth
If symbol = "B" Or symbol = "W" Then
getBCSymbolWidth = _wideBarWidth
End If
End Function
Protected Overridable Function GenerateBarcodeImage(ByVal imageWidth As Short, ByVal imageHeight As Short, ByVal Code As String) As MemoryStream
'create a new bitmap
Dim b As New Bitmap(imageWidth, imageHeight, Imaging.PixelFormat.Format32bppArgb)
'create a canvas to paint on
Dim canvas As New Rectangle(0, 0, imageWidth, imageHeight)
'draw a white background
Dim g As Graphics = Graphics.FromImage(b)
g.FillRectangle(Brushes.White, 0, 0, imageWidth, imageHeight)
'write the unaltered code at the bottom
'TODO: truely center this text
Dim textBrush As New SolidBrush(Color.Black)
g.DrawString(Code, New Font("Courier New", 12), textBrush, 100, 110)
'Code has to be surrounded by asterisks to make it a valid Code39 barcode
Dim UseCode As String = String.Format("{0}{1}{0}", "*", Code)
'Start drawing at 10, 10
Dim XPosition As Short = 10
Dim YPosition As Short = 10
Dim invalidCharacter As Boolean = False
Dim CurrentSymbol As String = String.Empty
For j As Short = 0 To CShort(UseCode.Length - 1)
CurrentSymbol = UseCode.Substring(j, 1)
'check if symbol can be used
If Not IsNothing(_encoding(CurrentSymbol)) Then
Dim EncodedSymbol As String = _encoding(CurrentSymbol).ToString
For i As Short = 0 To CShort(EncodedSymbol.Length - 1)
Dim CurrentCode As String = EncodedSymbol.Substring(i, 1)
g.FillRectangle(getBCSymbolColor(CurrentCode), XPosition, YPosition, getBCSymbolWidth(CurrentCode), _barHeight)
XPosition = XPosition + getBCSymbolWidth(CurrentCode)
Next
'After each written full symbol we need a whitespace (narrow width)
g.FillRectangle(getBCSymbolColor("w"), XPosition, YPosition, getBCSymbolWidth("w"), _barHeight)
XPosition = XPosition + getBCSymbolWidth("w")
Else
invalidCharacter = True
End If
Next
'errorhandling when an invalidcharacter is found
If invalidCharacter Then
g.FillRectangle(Brushes.White, 0, 0, imageWidth, imageHeight)
g.DrawString("Invalid characters found,", New Font("Courier New", 8), textBrush, 0, 0)
g.DrawString("no barcode generated", New Font("Courier New", 8), textBrush, 0, 10)
g.DrawString("Input was: ", New Font("Courier New", 8), textBrush, 0, 30)
g.DrawString(Code, New Font("Courier New", 8), textBrush, 0, 40)
End If
'write the image into a memorystream
Dim ms As New MemoryStream
Dim encodingParams As New EncoderParameters
encodingParams.Param(0) = New EncoderParameter(Encoder.Quality, 100)
Dim encodingInfo As ImageCodecInfo = FindCodecInfo("PNG")
b.Save(ms, encodingInfo, encodingParams)
'dispose of the object we won't need any more
g.Dispose()
b.Dispose()
Return ms
End Function
Protected Overridable Function FindCodecInfo(ByVal codec As String) As ImageCodecInfo
Dim encoders As ImageCodecInfo() = ImageCodecInfo.GetImageEncoders
For Each e As ImageCodecInfo In encoders
If e.FormatDescription.Equals(codec) Then Return e
Next
Return Nothing
End Function
End Class
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