我想从我的应用程序创建Code39编码的条形码.
我知道我可以使用这种字体,但是我不想像在服务器上注册字体那样,我已经有了一些不好的经历.
在提出这个问题之后,我提出的一个例子就是答案
这是我目前的codebehind,有很多评论：
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,imageWidth,imageHeight)
'draw a white background
Dim g As Graphics = Graphics.FromImage(b)
g.FillRectangle(Brushes.White,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"),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,imageHeight)
g.DrawString("Invalid characters found,",8),0)
g.DrawString("no barcode generated",10)
g.DrawString("Input was: ",30)
g.DrawString(Code,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