Using The TAL Bar Code ActiveX Plus with a Perl CGI Script
What is CGI?
"CGI" stands for "Common Gateway Interface". CGI
is a popular method by which a web server can obtain data from (or send
data to) databases, documents, and other programs, and present that data
to viewers via the web. More simply, CGI is programming for the web. A
CGI can be written in any programming language, but Perl is the most popular.
System Requirements
- PERL 5 or later for Windows.
- A Microsoft Windows based Server running either Microsoft
Personal Web Server (PWS)
or Microsoft Internet Information
Server (IIS).
- TAL Bar Code ActiveX Control (Plus version).
- Microsoft Internet Explorer 4.01 or higher (recommended)
- Microsoft Visual Basic 6.0 (To create and compile your own VB program)
Discussion
While investigating how to create server side bar codes, we found that
it is possible to use Perl CGI code to do the job however it was also
determined that using Active Server Pages
is far easier, quicker and requires less work to implement. Since we had
developed a method of using a Perl CGI Script (with some help from a compiled
Visual Basic program) to achieve the same results as our ASP
page example, we have included here.
How it works
The user completes an HTML form with information about the bar code
they wish to create, such as the symbology, the text to be encoded, the
text for the comment, etc. and submits the information to the server.
This information is decoded by the Perl script and passed to an executable
program, written in Visual Basic. The VB program generates a bar code
to the visitors' specifications and saves it as an image file with a unique
filename. The unique filename is based on a number, generated by the Perl
script using a file called "Counter.txt". Counter.txt contains
nothing more than a number, which the Perl script reads into a variable
called "$COUNT". Count is then incremented and the text file
updated. The script then passes the number to the VB program along with
the form data.
The VB program also generates some HTML that can be used to display the
image the correct size in the visitors browser, and saves it to a text
file. The Perl Script opens this text file and copies the HTML from it
as it generates the page to display in the Browser.
How to use this Example
 Download,
unzip and install Perl 5.- Configure your Web Server
to run Perl scripts
- Download
the files discussed in the example below. This is a self extracting
zip file containing the HTML form,
the Perl script, the Visual Basic
project files, the compiled program for those of you who do not have
Visual Basic, but would still like to test it, and the "counter"
file.
- Extract the files. Copy "Getbarcode.exe","Barcode.pl"
and "counter.txt" into your "Scripts" folder (usually
"C:\Webshare\Scripts").
- Copy "perlForm.htm" into the root directory of your web
site (usually C:\Webshare\Wwwroot).
- Open your Web browser and type in "http://your.Server.name/perlForm.htm"
into the address line, change the properties that interest you on the
form, and submit it. You should be rewarded with a barcode. If you are
not, check out the Troubleshooting section
at the end of this document.
- If you have Visual Basic 6 you can open the VB project and make changes
to the "Getbarcode" program and recompile it. (If you have
an older version of Visual Basic you may not be able to open the project
but can still import the form and the module, or copy and paste the
code from this page into your own project).
Sample HTML Form
Click here to view the sample form.
Sample Perl Script
# Tell the server
that this is a Perl Script, and where to find the Perl interpreter.
# This should point to your Perl location
#!C:/Perl5/bin/perl.exe
# This is a content
header that tells the receiving web browser what sort of data it is about
to receive, in this case an HTML document. (If you omit this line you
will receive an internal server error in your Browser when the script
is run).
print "Content-type:text/html\n\n";
# Decode data from form - The following routine
is a standard piece of code used to decode form data submitted via the
POST method and can be reused without any need for
modification:
#################### Start decoding data ##################
# We're using Perl's read function to store the
data into a variable called "$buffer". The read function has
3 arguments: read(FILEHANDLE, $variable, $length). The input stream
is coming over STDIN (standard input), we're storing the data in a variable
called $buffer, and the length of the data is determined by the Server's
Environment Variable "CONTENT_LENGTH".
read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
# Next we split
the buffer into an array of pairs:
@pairs = split(/&/, $buffer);
# The data pairs
are separated by "&" signs when they are transmitted, such
as
# fname=joe&lname=smith. Now we'll use a foreach loop to further split
each pair:
foreach $pair (@pairs) {
# First using
using the "=" sign:
($name, $value) = split(/=/, $pair);
# next we translate every "+" sign back
into a space:
$value =~ tr/+/ /;
# The next line
is a rather complicated expression that substitutes every %HH
# hex pair back to its equivalent ASCII character by using the pack()
function:
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/e.g.;
# Finally, we
store the values into a hash variable called %FORM (a hash is a 2 dimensional
array which is used to pair elements - a key and a data value). For example,
in the %FORM hash we are storing the name of the field and the value of
that field. Suppose you have a form with a text box called "FirstName"
and the user types in "Joe" and submits the form to be processed
by this script. When this routine decodes the data the %FORM hash would
look like this:
# %FORM =
("FirstName", "Joe")
# In order to print "your firstname is Joe" onto the HTML page
you would type:
# print "your firstname is $FORM{$FirstName}";
$FORM{$name} = $value;
}
#####################
End Decoding Data ########################
# To simplify referring to the form data later in the script you can store
each form field into a new variable name:
$message = $FORM{'txtMessage'};
$scrHeight = $FORM{'scrHeight'};
$scrWidth = $FORM{'scrWidth'};
$Browser = $FORM{'Browser'};
$Version = $FORM{'Version'};
$Comment = $FORM{'txtComment'};
$CommentAlign = $FORM{'commentalignment'};
$Barheight = $FORM{'barheight'};
$Narrowbarwidth = $FORM{'narrowbarwidth'};
$Symbology = $FORM{'symbology'};
$Rotation = $FORM{'rotation'};
$Forecolor = $FORM{'forecolor'};
$Backcolor = $FORM{'backcolor'};
$Quietzones = $FORM{'quietzones'};
$Bearerbars = $FORM{'bearerbars'};
# Insert Header HTML:
print "<html><head><title>Server Side Barcoding
Test</title></HEAD><Body>";
# Alternatively, if you had a text file containing
your HTML header information (Perhaps you have a standard header on every
page of your site containing logos and JavaScript etc.,) you could 'import'
it using the following code rather than reproduce it all here:
# Read the file
"header.txt" into a variable called "INF". Note: "header.txt
is assumed in this case to be in the same folder as the executing script,
usually the "cgi-bin" folder.
# open(INF,"header.txt");
# Convert INF
into an array variable called "@ary"
# @ary = <INF>;
# Close the file
header.txt
# close(INF);
# for each line in @ary...
# foreach $line(@ary){
# remove trailing
line feeds
# chomp($line);
# print the line
to the HTML file we are creating
# print "$line\n";
# }
# In order to
avoid the possibility of 2 users creating the same file at the same time
we use a unique file number for each image file.
# Create variable
representing the Maximum number of image files to store on server. This
should exceed expected number of concurrent users or one user could be
overwriting another's image. We shall use this number when incrementing
the filename:
# If the last filename (number) is the same as our
maximum number of files, then reset the numbering to 1, otherwise increment
the number.
$maxfiles = 10;
# open the counter
file with read and write access.
Open(COUNTER, "+< counter.txt");
# read the current value.
$COUNT = <COUNTER>;
if ($COUNT < $maxfiles) {
# increment it by one.
$COUNT++;
}
else {
# Reset counter
$COUNT = 1;
}
#rewind the file.
seek(COUNTER, 0 , 0);
#write the new value to the file.
print COUNTER $COUNT;
close COUNTER;
# Interacting
with the Visual Basic Program:
# Because we cannot initialize or use the ActiveX control directly in
Perl, we shall send the form information to a compiled Visual Basic Program,
which will generate the barcode, save it as an image file and write a
line of HTML to include the resulting image in this web page: First we
send the form information (in tilde delimited format with no spaces):
$errcode = system("C:\\webshare\\scripts\\getbarcode.exe $COUNT~$Browser~$Version~$message
~$Comment~$CommentAlign~$Barheight~$Narrowbarwidth~$Symbology~$Rotation~$Forecolor
~$Backcolor~$Quitzones~$Bearerbars");
# The system command allows us to run an external
program and then continue running this script.
# 2 Backslashes ("\") are needed because in Perl the backslash
is an escape key, in other words when the Perl interpreter sees a backslash
it ignores the meaning of the next character. We are saving the value
returned by the system command into a variable called $errcode. If the
system command runs as expected $errcode will be 0, otherwise there will
be a value other than 0. It is important to know this since whether the
system command runs correctly or not the Perl script will continue to
execute.
# If the system command fails, or the results are unexpected, you may
wish to capture the command line for debugging purposes.
# Here we send
the same string we sent to the system command, to a text file called "outdata.txt".
The ">" sign indicates that we are opening outdata.txt for
overwriting as opposed to appending:
open(OUT, ">outdata.txt");
print OUT "C:\\webshare\\scripts\\getbarcode.exe $COUNT~$Browser~$Version~$message
~$Comment~$CommentAlign~$Barheight~$Narrowbarwidth~$Symbology~$Rotation~$Forecolor
~$Backcolor~$Quitzones~$Bearerbars";
close(OUT);
# If the errcode is not 0 then there was an error running our VB program.
If this is the case there is no point trying to display the image since
it was never generated. Instead we display an error:
if ($errcode != 0){
print "There was a problem running a system command on the Server
- Error: $errcode";
}
else {
# If there was no error then we open the html file
created by the VB program that contains the image information and copy
its contents:
open(INF,"C:\\webshare\\wwwroot\\image$COUNT.html");
@ary = <INF>;
close(INF);
foreach $line(@ary){
chomp($line);
print "$line\n";
}
}
# insert an HTML
line feed for a new line and explain what lies beneath
print "<br><hr><h2>The following data was submitted:</h2>";
# Display all
the data received from the form:
foreach $key (keys(%FORM)) {
print "$key = $FORM{$key}<Br>\n";
}
print "Current counter number
is: $COUNT";
# Insert Footer HTML:
print "</Body></html>";
# Alternatively,
if you have a long footer that you always insert at the bottom of a web
page you can copy and paste it into a text file and save it as footer.txt,
then have your scripts open and read it into the web page on the fly in
the same way that we insert the image information and html header information
above.
# Open(INF,"footer.txt");
# @ary = <INF>;
# close(INF);
# foreach $line(@ary){
# chomp($line);
# print "$line\n";
# }
Sample Visual Basic Code
Module 1 Code
This is the code that generates the barcodes. The parameters specified
by the user are passed by the Perl Script to this routine as one long
string of data separated by the tilde (~) character. The routine below
parses out the parameters into an array of data, then sets the properties
of the activeX control with the data supplied by the user. The properties
are matched to the data based on the order in which they were received.
The barcode is then saved as an image file using the SaveBarCode Method.
The image is saved in a format appropriate for the user's Browser (PNG
is preferable because its compression technique generates smaller images
than GIF files, meaning that the page will load faster and less space
is required on the server). The HTML code required to display the image
is written to a text file with the same name as the image, which the perl
script opens up and uses to display the final image on the page.
Note: In the code below there is no data validation to verify that submitted
data is appropriate for the symbology selected, nor does it check to see
if all required information was supplied. If you plan to use this technique
such additional checking will be required.
Sub Main()
'Declare variables
Dim cmdline$, i As Long
Dim StartPos As Long, DelimPos As Long
Dim MyArray(15), lngPixelsPerInch As Long
Dim pxlHeight As Long, pxlWidth As Long
Dim filenum As Long, ImagePath As String
'set number of pixels per inch (Windows always assumes
96 regardless of screen resolution)
lngPixelsPerInch = 96
'Visitors to the page will use the HTML form to
record information about the barcode they wish to generate, for example
the message to be encoded, the symbology, and the height of the bars.
This program will look at the form data (passed by the Perl Script), set
the Properties of the ActiveX control to those specified on the form,
then generate a barcode image .PNG or .GIF (depending on the Browser since
not all browsers suport .PNG files). This Barcode Image must be saved
on the Server, so we shall specify a folder in which to save it. The filename
has to be different for every visitor or one visitors barcode will be
overwritten by the next. To this end we shall use an incrementing filename:
"1.png", "2.png", etc. In order for the Server to
"remember" the last filename it created, we must store it somewhere
on the server, so we shall create a registry key to store the latest file
number used and then read the last number from the registry and add one
to it when generating the next one:
'get path to save images to
ImagePath = GetSetting("BCGen", "Settings", "imagepath",
"C:\Webshare\Wwwroot\")
'Get command line arguments used to call this program
cmdline$ = Command$
'If you need to see what was received from the Perl
script use:
'MsgBox "You typed:" & cmdline$
'if arguments were passed:
If Len(cmdline$) Then
'add final delimiter
cmdline$ = Command$ + "~"
'decode command line: separate each argument into
an array
StartPos = 1
i = 1
While StartPos < Len(cmdline$)
DelimPos = InStr(StartPos, cmdline$, "~")
MyArray(i) = Mid$(cmdline$, StartPos, DelimPos - StartPos)
StartPos = DelimPos + 1
i = i + 1
Wend
'MyArray looks like = (Counter, Browser, version, message, comment, comment
alignment, bar height, _
Narrow bar width, symbology, rotation, foreground, background, quitzones,
bearerbars)
'file number variable is to prevent multiple users
seeing the same file
filenum = MyArray(1)
'set activeX properties based on command line arguments
'This program assumes that all these arguments are passed, additional
checking will be required
'if some arguments are null
'Also, by setting the relevent controls on the form to the new values,
the dafaults can be changed
'Note: Properties that you do not set will use their default values
MainForm.TALBarCd1.Message = MyArray(4)
MainForm.TALBarCd1.Comment = MyArray(5)
MainForm.TALBarCd1.CommentAlignment = MyArray(6)
MainForm.TALBarCd1.BarHeight = MyArray(7)
MainForm.txtBarHeight = MyArray(7)
MainForm.TALBarCd1.NarrowBarWidth = MyArray(8)
MainForm.txtNarrowBW = MyArray(8)
MainForm.TALBarCd1.Symbology = MyArray(9)
MainForm.Combo1.ListIndex = MyArray(9)
MainForm.TALBarCd1.Rotation = MyArray(10)
MainForm.Combo2.ListIndex = MyArray(10)
MainForm.TALBarCd1.ForeColor = MyArray(11)
MainForm.TALBarCd1.BackColor = MyArray(12)
'in HTML forms unchecked checkboxes return nulls
If MyArray(13) = "" Or IsNull(MyArray(13)) Then
'no quietzones
MainForm.TALBarCd1.QuietZones = False
Else
MainForm.TALBarCd1.QuietZones = True
End If
If MyArray(14) = "" Or IsNull(MyArray(14)) Then
'no bearer bars
MainForm.TALBarCd1.BearerBars = False
Else
MainForm.TALBarCd1.BearerBars = True
End If
'Get height and width for display in Browser
pxlWidth = ConvertTwipsToPixels(MainForm.TALBarCd1.Width, lngPixelsPerInch)
pxlHeight = ConvertTwipsToPixels(MainForm.TALBarCd1.Height, lngPixelsPerInch)
'Check Browser and version, create .Png file if
supported, otherwise .gif
If MyArray(2) = "Microsoft Internet Explorer" And MyArray(3)
>= 4 Then
'save barcode in chosen directory in a format suitable
for the browser (The form uses JavaScript to evaluate the browser, then
writes the most suitable filetype to a "hidden" field in the
form called "Imagetype". When we requested the form information
from the server "Imagetype" was saved into a new variable called
"strFileType". Below we concatenate 3 variables together in
order to save the barcode:
MainForm.TALBarCd1.SaveBarCode ImagePath & filenum & ".png"
'Since our ImgDir is stored in a constant above
as "c:\webshare\wwwroot\", filenum will be a number between
1 and 10 (since 10 is the maximum number of files we wish to store on
the server) and strFileType will be either "PNG" or "GIF".
The "&" character simply joins the three variables together
in order to create a single string, for example ""c:\webshare\wwwroot\6.png"
'Write HTML to output file to be read by script
when final page generated
Open "c:\webshare\wwwroot\image" & filenum & ".html"
For Output As #1
Print #1, "<img src='../" & filenum & ".png'
width='" & pxlWidth & "' height='" & pxlHeight
& "'>"
Close #1
Else
MainForm.TALBarCd1.SaveBarCode ImagePath & filenum & ".gif"
'Write HTML to output file to be read by script when final page generated
Open "c:\webshare\wwwroot\image" & filenum & ".html"
For Output As #1
Print #1, "<img src='../" & filenum & ".gif'
width='" & pxlWidth & "' height='" & pxlHeight
& "'>"
Close #1
End If
'unload form from memory
Unload MainForm
Else
'no command line arguments specified: show form
MainForm.Show
End If
End Sub
'The following
function is required because we intend to insert a Raster style image
into the resulting web page. The dimensions of a Raster image are dependent
upon the dot resolution of the device used to display it. For example
a graphic that is 300 pixels wide and has 300 rows of pixels displayed
on a printer that has a dot resolution of 300 dots per inch will be one
inch square. But if you display the same image on a computer screen that
has a dot resolution of approx 100 dots per inch, you end up with an image
that is three inches square. When we Query the ActiveX control to find
out it's height and Width the returning information is in "Twips".
In order to Set the Height and Width Properties of the <IMG> tag,
we need this information to be converted into Pixels.
Function ConvertTwipsToPixels(lngTwips As Long, _
lngPixelsPerInch As Long) As Long
Const nTwipsPerInch = 1440
ConvertTwipsToPixels = (lngTwips
* lngPixelsPerInch) / nTwipsPerInch
End Function
Form code
If no command line arguments are passed to the program the following
form appears. It can be used by the administrator to set the Default settings
on the Server. If command line arguments are passed to the form, then
the form will not be displayed.
This is the code behind the Visual Basic Main Form:
Private Sub chkBearer_Click()
'set Bearer bars
TALBarCd1.BearerBars = chkBearer.Value
End Sub
Private Sub chkQuiet_Click()
'set quiet zones
TALBarCd1.QuietZones = chkQuiet.Value
End Sub
Private Sub cmdBrowse_Click()
'This routine displays a dialog box from which the
user can select a folder
PathForm.Show 1
End Sub
Private
Sub Combo1_Click()
'Set Symbology
TALBarCd1.Symbology = Combo1.ListIndex
End Sub
Private Sub Combo2_Click()
'Set rotation
TALBarCd1.Rotation = Combo2.ListIndex
End Sub
Private Sub Combo3_Click()
'set comment alignment
TALBarCd1.CommentAlignment = Combo3.ListIndex
End Sub
Private Sub Combo4_Click()
'set Fore color
Select Case Combo4.ListIndex
Case 0: C& = 0
Case 1: C& = &HFFFFFF
Case 2: C& = &HFF
Case 3: C& = &HFF00&
Case 4: C& = &HFF0000
End Select
TALBarCd1.ForeColor = C&
End Sub
Private Sub Combo5_Click()
'Set Back color
Select Case Combo5.ListIndex
Case 0: C& = 0
Case 1: C& = &HFFFFFF
Case 2: C& = &HFF
Case 3: C& = &HFF00&
Case 4: C& = &HFF0000
End Select
TALBarCd1.BackColor = C&
End Sub
Private Sub Dir1_Change()
'After changing the image path update the textbox
on the form
txtImagePath.Text = Dir1.Path
End Sub
Private Sub Form_Load()
'When the form loads...
'fill Symbology dropdown with list of symbologies
Combo1.AddItem "Code 39"
Combo1.AddItem "Code 39 Full ASCII"
Combo1.AddItem "Code 39 HIBC"
Combo1.AddItem "Codabar"
Combo1.AddItem "Code 93"
Combo1.AddItem "Code 128"
Combo1.AddItem "EAN/UCC 128"
Combo1.AddItem "Interleaved 2 of 5"
Combo1.AddItem "Postnet"
Combo1.AddItem "UPC-A"
Combo1.AddItem "UPC-E"
Combo1.AddItem "EAN-8"
Combo1.AddItem "EAN-13"
Combo1.AddItem "Bookland"
Combo1.AddItem "MSI/Plessey"
Combo1.AddItem "PDF417"
Combo1.AddItem "Aztec Code"
Combo1.AddItem "Data Matrix"
Combo1.AddItem "Maxicode"
'Get the last symbology used from the registry.
Combo1.ListIndex = GetSetting("BCGen", "Settings",
"Symbology", "0")
'fill Rotation dropdown
Combo2.AddItem "0 Degrees"
Combo2.AddItem "90 Degrees"
Combo2.AddItem "180 Degrees"
Combo2.AddItem "270 Degrees"
'Get the
last Rotation setting from the registry.
Combo2.ListIndex = GetSetting("BCGen", "Settings",
"Rotation", "0")
'fill Comment alignment dropdown
Combo3.AddItem "Left"
Combo3.AddItem "Center"
Combo3.AddItem "Right"
'Get the
last Comment Alignment setting from the registry.
Combo3.ListIndex = GetSetting("BCGen", "Settings",
"commentAlignment", "0")
'fill Fore Color dropdown
Combo4.AddItem "Black"
Combo4.AddItem "White"
Combo4.AddItem "Red"
Combo4.AddItem "Green"
Combo4.AddItem "Blue"
'Get the
last Forecolor setting from the registry.
Combo4.ListIndex = GetSetting("BCGen", "Settings",
"ForeColor", "0")
'fill Back Color dropdown
Combo5.AddItem "Black"
Combo5.AddItem "White"
Combo5.AddItem "Red"
Combo5.AddItem "Green"
Combo5.AddItem "Blue"
'Get the
last Backcolor setting from the registry.
Combo5.ListIndex = GetSetting("BCGen", "Settings",
"BackColor", "1")
'MainForm.TALBarCd1.BackColor = Combo5.ListIndex
'Get the last Image resolution used from the registry
or use a default of 300
txtImageResolution = GetSetting("BCGen", "Settings",
"RasterResolution", "300")
'set image resolution property
MainForm.TALBarCd1.RasterImageResolution = txtImageResolution.Text
'Get the last Narrow Bar Width setting from registry
or use a default of 13
txtNarrowBW = GetSetting("BCGen", "Settings", "NarrowBarWidth",
"13")
'set narrow bar width property
MainForm.TALBarCd1.NarrowBarWidth = txtNarrowBW.Text
'Get the last BarHeight setting from registry or
use a default of 1000
txtBarHeight = GetSetting("BCGen", "Settings", "BarHeight",
"1000")
MainForm.TALBarCd1.BarHeight = txtBarHeight.Text
'Get the last Bar Width Reduction setting from registry
or use a default of 0
txtBarWidthRed = GetSetting("BCGen", "Settings", "BarWidthReduction",
"0")
MainForm.TALBarCd1.BarWidthReduction = txtBarWidthRed.Text
'Get the last Matrix Module size setting from registry
or use a default of 20
txtMatrixModSize = GetSetting("BCGen", "Settings",
"MatrixModuleSize", "20")
MainForm.TALBarCd1.MatrixModuleSize = txtMatrixModSize.Text
'Get the last Quiet Zones setting from registry
or use a default of 1 (meaning "On")
chkQuiet = GetSetting("BCGen", "Settings", "QuietZones",
"1")
MainForm.TALBarCd1.QuietZones = chkQuiet.Value
'Get the last BearerBars setting from registry or
use a default of 0 (meaning "Off")
chkBearer = GetSetting("BCGen", "Settings", "BearerBars",
"0")
MainForm.TALBarCd1.BearerBars = chkBearer.Value
End Sub
Private Sub Form_Unload(Cancel
As Integer)
'save new settings to the registry
SaveSetting "BCGen", "Settings", "Symbology",
Combo1.ListIndex
SaveSetting "BCGen", "Settings", "Rotation",
Combo2.ListIndex
SaveSetting "BCGen", "Settings", "CommentAlignment",
Combo3.ListIndex
SaveSetting "BCGen", "Settings", "ForeColor",
Combo4.ListIndex
SaveSetting "BCGen", "Settings", "BackColor",
Combo5.ListIndex
SaveSetting "BCGen", "Settings", "imagepath",
txtImagePath
SaveSetting "BCGen", "Settings", "RasterResolution",
txtImageResolution
SaveSetting "BCGen", "Settings", "NarrowBarWidth",
txtNarrowBW
SaveSetting "BCGen", "Settings", "BarHeight",
txtBarHeight
SaveSetting "BCGen", "Settings", "BarWidthReduction",
txtBarWidthRed
SaveSetting "BCGen", "Settings", "MatrixModuleSize",
txtMatrixModSize
SaveSetting "BCGen", "Settings", "QuietZones",
chkQuiet
SaveSetting "BCGen", "Settings", "BearerBars",
chkBearer
End Sub
Private Sub mExit_Click()
'exit from menu
Unload Me
End Sub
Private Sub Text1_Change()
'When user types new text into Message text box,
update barcode
TALBarCd1.Message = Text1.Text
End Sub
Private Sub Text2_Change()
'When user types new text into Comment text box,
update barcode
TALBarCd1.Comment = Text2.Text
End Sub
Private Sub txtImagePath_Change()
'if the imagepath is typed in without a trailing
backslash, then put one in
If Right(Me.txtImagePath, 1) <> "\" Then
Me.txtImagePath = Me.txtImagePath + "\"
End If
End Sub
Private Sub txtBarHeight_Change()
'if the bar height is changed to a value between
11 and 6999 then set the bar height, otherwise beep.
If Val(txtBarHeight.Text) > 10 And Val(txtBarHeight.Text) < 7000
Then
TALBarCd1.BarHeight = Val(txtBarHeight.Text)
Else
Beep
End If
End Sub
Private Sub txtBarWidthRed_Change()
'if the bar width reduction is changed to a value
between 99 and -99 then set the bar width reduction, otherwise beep.
If (Val(txtBarWidthRed.Text) < 100) And (Val(txtBarWidthRed.Text) >
-100) Then
TALBarCd1.BarWidthReduction = Val(txtBarWidthRed.Text)
Else
Beep
End If
End Sub
Private Sub txtMatrixModSize_Change()
'if the Matrix Module size is changed to a value
between 1 and 64 then set the Matrix
Module size, otherwise beep.
If Val(txtMatrixModSize.Text) > 0 And Val(txtMatrixModSize.Text) <
65 Then
TALBarCd1.MatrixModuleSize = Val(txtMatrixModSize.Text)
Else
Beep
End If
End Sub
Private Sub txtNarrowBW_Change()
'if the narrowbarwidth is changed to a value between
1 and 99 then set the narrowbarwidth, otherwise beep.
If Val(txtNarrowBW.Text) > 0 And Val(txtNarrowBW.Text) < 100 Then
TALBarCd1.NarrowBarWidth = Val(txtNarrowBW.Text)
Else
Beep
End If
End Sub
Troubleshooting
How do I find out what the homepage or root directory of my web server
is?
If you do not know your Server name or the root directory of your web
server, then double click on the Web Server icon in your system tray to
find out:
If you are running an older version of PWS or FrontPage Web Server, then
your icon and PWS manager may look like this:
When I submit the Form there is a broken link where the barcode image
should be
The most likely causes of this problem are:
- Check that the line of code that saves the barcode is saving it to
the same folder that the <IMG> tag expects to find it in. For
example, in our code above we are saving the image into the root directory
of the website. If we were to set the "src" (source) attribute
to our image tag incorrectly (such as having it look in the scripts
folder) we would get a broken link since the image is not going to be
in that folder..
- Verify that the image is being created in the specified folder. If
the image is not being created then it may be a permissions issue. Check
that the public has write access to the folder in which you wish to
save the barcodes.
- You tried to create a barcode with invalid parameters. (More
information).
When I submit the Form I receive "Cannot find Server"
Verify that you have started the Web Server by double clicking on the
icon in the system tray if a button marked "Start" is available
then click on it to start the Web Server If the button says "Stop"
then try stopping and restarting the Web Server.
If this does not resolve the problem make sure that you opened the form
via http, rather than as a file on your hard drive. In other words, the
address line in your Browser should read: "http://your.Server.Name/perlForm.htm"
not "C:\WEBSHARE\WWWROOT\perlForm.htm".
When I submit the Form I receive "HTTP 404 Not Found"
This error means that the script (or the form) is in the wrong folder.
For example, you may have copied both the form and the script into your
"Scripts" folder (C:\WEBSHARE\Scripts). Since your Web Server's
name is different to ours we used a relative link when telling
the form where the barcode.asp script is located. When you submit the
form, it tells the Web Server that the script is one level deeper than
the form on the server, inside a folder called "Scripts". If
the form is already inside that folder, then the Server is looking for
C:\WEBSHARE\Scripts\Scripts. Since this folder probably does not exist
it cannot find the script it is looking for. To resolve the problem, either
move the form to the C:\WEBSHARE\WWWRoot folder, or change the <Form>
tag in the html form to point to where the Script actually is. In this
example, changing the line <form
METHOD="POST" NAME="BarCodeForm" action="scripts/barcode.pl">
to read <form
METHOD="POST" NAME="BarCodeForm" action="barcode.pl">
would resolve the problem.
When I submit the Form I receive "HTTP Error 403 403.1 Forbidden"
This error indicates that the folder into which you copied the barcode.pl
and "Getbarcode.exe" file does not have execute permissions.
Either move the files to a folder that does have execute permissions such
as the "Scripts" Folder, or grant execute permissions to that
folder.
To grant execute permissions, open the Personal Web Server Manager, click
on "Advanced", double click on the folder you wish to use, then
check the "Execute" and "Scripts" checkboxes and click
"OK". (On older versions of Personal Web Server click on "Administration",
and then change the properties of the folder).
When I submit the Form I receive "HTTP Error 405 - Method Not allowed"
This error means that your server is not configured to run Perl scripts.
Configure your server
to run Perl Scripts. If restarting the server doesn't work then reboot
the server machine.
When I submit the Form I receive "Error 500 - Internal Server Error"
This means that there is a syntax error in your Perl script. The best
way to find it is to open an MSDOS window, navigate to the directory where
you installed Perl and type: Perl -c script.pl
(where "script.pl" is the name of your script. Note: If you
script is in a different folder to the Perl interpreter - which for the
sake of security it certainly should be! - then you must specify the full
path to the script: e.g. Perl -c C:\webshare\wwwroot\CGI-bin\script.pl).
The "-c" argument tells Perl to compile the script without actually
executing it.
If there is a compilation error Perl will inform you which line the error
is on and often why the error occurred. Common syntax errors that cause
an Error 500 include:
- "Missing semicolon in previous line."
- "Can't find terminator before EOF." This message is usually
the result of a missing right bracket or quotation mark.
- "Might be a runaway multi-line string starting on line n."
This is usually a missing quotation mark.
- "Missing right bracket"
By using Perl to compile your script you can turn a very baffling Error
500 into a simple "whoops I seem to have forgotten to close my quotations
on line 10".
It is also extremely important to remember that Perl is case sensitive.
If you create a variable called $test and then later refer to it as $Test
you will get unexpected results since $Test is considered by Perl to be
a new and empty variable. For example:
$X = 6;
$Y = $x + 2;
print "$X + 2 = $Y";
Clearly, when the code was written I expected to print 6 + 2 = 8 onto
my web page, but what I actually get is 6 + 2 = 2. While in this case
we would not get a Server error, we would not get the result we expected
and would be left looking rather silly.
When I submit the Form I see the Perl script as a text document
This means that your server is not configured to run Perl scripts. Configure
your server to run Perl Scripts. If restarting the server doesn't
work then reboot the server machine.
When I try to run the Getbarcode.exe program it generates an "automation
error" or something about a missing DLL file?
To resolve the problem, the latest Visual Basic Runtime files must be
installed onto the client machine before the program can run successfully.
Where Do I Get these files?
The VBRUN60.EXE file is available for download from the following site:
Vbrun60.exe
(size: 1.34MB)
Reference :
For additional information, please see the following article in the Microsoft
Knowledge Base:
ARTICLE-ID : Q192461
TITLE : FILE: VBRUN60.EXE
Installs Visual Basic 6.0 Run-Time Files
If I change the symbology I sometimes get a broken
link or a totally different barcode stretched out of proportion, why is
this?
In our Example, we did not include any code to validate the data. Some
Barcode symbologies have very strict rules about what can be encoded,
UPC-A for instance, can only accept a 12 digit numeric message. If you
type in "Test" and select UPC-A then the activeX control produces
an error and sets the size properties back to the dafaults for code 39
encoded with 1234567890, but it does not save a barcode to disk. You will
recall that we allowed for 10 unique barcodes to be generated before it
rolls over and starts overwriting. If you haven't yet created 10 barcodes
then you will probably get a broken link, otherwise you will get a distorted
image of the last number n barcode.
To prevent this from happening you should write some code to do some
basic data validation before and/or after the form data is submitted using
javascript, Perl and/or VB code. You should also create a page or message
that appears to inform the user that they entered invalid parameters.
Examples of these techniques will be made available soon.
Related Links
Introduction to Active Server Pages
Using TAL Bar Code ActiveX Plus with Active
Server Pages
How to install Perl scripts
on IIS and PWS
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