TBarCodeDLL-Board the Barcode Bandwagon, Page 2

Your First Barcode App

The demo program is nice, but let's see some source code and how it really works. Breaking it down to the simplest level, we will look at Tec-It's simplest provided C++ application. I'm a command-line kind of guy, so I used the following to compile and link in one step:

cl TBCDLLSample.cpp /Z7 /link /DEBUG TBarCode6.lib gdi32.lib user32.lib

Then, when I ran the app, the first thing it complained about was not finding TBarCode6.OCX. I located a copy of the OCX in the redist directory and punched in the OCX as follows:

regsvr32 Tbarcode6.ocx

This program is the smallest useful sample you can write. It performs the following tasks:

1. Creates a Code128 barcode
2. Draws the barcode onto a bitmap
3. Burns the bitmap into a .JPG file

The following section goes through several areas of the program and makes some notes on what is happening in each:

  1 // TBCDLLSample.cpp: Defines the entry point for the console application.
  2 //
  3
  4 #include "stdafx.h"
  5 #include <Windows.h>
  6 #include <WTypes.h>
  7
  8 // include the header files for TBARCODE DLL
  9 #define     TECIT_DLLIMPORT
 10 #include "TBarCodeDLL.h"
 11 #undef      TECIT_DLLIMPORT
 12
 13
 14 /// include the tbarcode5.lib file to the linker section
 15
 16 //////////////////////////////////////////////////////////////////
 17 // TBarCode DLL Sample
 18 //////////////////////////////////////////////////////////////////
 19 int main(int argc, char* argv[]) {
 20 ERRCODE     eCode = S_OK;
 21 LOGFONTA*   lf    = NULL;              // used to change font of barcode
 22 t_BarCode*  pBC;
 23 char*       szText;
 24 INT         nModules;
 25
 26   printf("TBarCode DLL Sample\n");
 27   printf("-------------------\n\n");
 28   printf("This program will create a sample barcode and save it as \"c:\\bitmap.jpg\".\n");
 29   printf("Barcode type: Code128\n");
 30   printf("Encoded data: HELLO WORLD\n\n");
 31
 32   // License at startup of your application; get your license key from http://www.tec-it.com/order/
 33   // BCLicenseMe( "Licensee String", eKindOfLicense, 1, "Your Key", eProductID); // for enums refer to  TECBCEnum.h
 34
 35   // allocate memory for internal barcode structure
 36   BCAlloc (&pBC);
 37
 38   // set the barcode type to Code 128
 39   // refer to TECBCEnum.h (or the documentation)
 40   eCode = BCSetBCType (pBC, eBC_Code128);
 41
 42   if (eCode == S_OK) {
 43     // set the barcode data to "HELLO WORLD"
 44     szText = "HELLO WORLD";
 45     eCode = BCSetText(pBC, szText, strlen(szText));
 46
 47     // change the font
 48     lf = BCGetLogFont(pBC);
 49     lf->lfHeight = 10;
 50     strcpy(lf->lfFaceName, "Arial");   // face name must not exceed 31 characters
 51
 52     // Use this commands if you want to change the module width:
 53     // BCSetModWidth (pBC, "254");     // Set module width to 0.254 mms
 54   }
 55
 56   // check if the input data contains valid characters (for the selected barcode type)
 57   if (eCode == S_OK)
 58     eCode = BCCheck(pBC);
 59
 60   // compute the check digits (depends on barcode and CD-method)
 61   if (eCode == S_OK)
 62     eCode = BCCalcCD(pBC);
 63
 64   // prepare the internal barcode info-structure to be drawn
 65   if (eCode == S_OK)
 66     eCode = BCCreate(pBC);
 67
 68   // get number of horizontal barcode elements
 69   if (eCode == S_OK)
 70     nModules = (INT) BCGetCountModules (pBC);
 71
 72   // draw barcode to device context
 73   if (eCode == S_OK) {
 74     RECT    rect;
 75     HDC     dc;
 76     HBITMAP BM;
 77
 78     dc  = CreateCompatibleDC(NULL);
 79     BM  = CreateCompatibleBitmap (dc, nModules * 2, 150); // area of Pixels
 80     SelectObject ( dc, BM );
 81
 82     rect.left   = 0;
 83     rect.bottom = 0;
 84     rect.right  = 5000;
 85     rect.top    = 3000;
 86
 87     SetMapMode(dc, MM_HIMETRIC);
 88     OffsetRect(&rect,100, 100);
 89
 90     eCode = BCDraw(pBC, dc, &rect); // draw barcode into device context
 91     DeleteObject (BM);
 92     DeleteDC(dc);
 93   }
 94
 95   // save barcode to image file
 96   if (eCode == S_OK) {
 97     // use number of horizontal elements as for the x dimension of the image
 98     // this avoids aliasing effects and ensures readability of barcode!
 99     eCode = BCSaveImage(pBC, "c:\\bitmap.jpg", eIMJpg, nModules, 150, 96, 96);
100   }
101
102   // show error message on demand
103   if (eCode != S_OK) {
104     // if an error occurred, display more info about the error
105     char szErr[32] = {0};
106     //ZeroMemory(szText, sizeof(szText));
107     BCGetErrorText(eCode, szErr, sizeof(szErr));
108     MessageBox(NULL, szErr, "Error creating barcode:", MB_OK);
109   }
110
111   // Important: frees the allocated memory of the barcode
112   BCFree(pBC);
113
114   printf("done.\n");
115   return eCode;
116 }

Boost to Human Productivity

TBarCode DLL and OCX solve a complex problem with a simple interface. If you need to print reports or stickers that can be scanned in the field to verify the presence of a part or piece of inventory, the lowly barcode can be a big boost to human productivity and cut down on data-entry errors and operator fatigue.

About the Author

Victor Volkman has been writing for C/C++ Users Journal and other programming journals since the late 1980s. He is a graduate of Michigan Tech and a faculty advisor board member for Washtenaw Community College CIS department. Volkman is the editor of numerous books, including C/C++ Treasure Chest and is the owner of Loving Healing Press. He can help you in your quest for open source tools and libraries, just drop an e-mail to sysop@HAL9K.com.