BARCODEREADOPT

Summary

This structure contains barcode read options that control the reading process.

Syntax

typedef struct tagBarCodeReadOpt 
{ 
   L_UINT32 ulSearchType; 
   L_INT nUnits; 
   L_UINT32 ulFlags; 
   L_INT nMultipleMax; 
   RECT rcSearch; 
   L_BOOL bUseRgn; 
   BARCODECOLOR BarColor; 
   BARCODEREADCALLBACK pfnCallback; 
   L_VOID* pUserData; 
} BARCODEREADOPT, *pBARCODEREADOPT; 

Members

ulSearchType

Type of barcode for which to search. You can combine values when appropriate, by using a bitwise OR ( | ). Possible values are:

Linear Barcode:

Patch Code Barcodes:

Postal barcodes:

4 State barcode symbols:

GS1 Databar (formerly RSS14) Stacked barcode symbols:

PDF Barcodes:

MicroPDF417 Barcodes:

QR Barcodes:

Data Matrix Barcode:

Aztec Barcode:

Maxi Barcode:

MicroQR Barcode:

Other barcode symbol:

nUnits

Unit of measure. Possible values are:

ulFlags

Processing options. You can combine values when appropriate, by using a bitwise OR ( | ). The following values are used only when you want to search for linear barcodes. Pass 0 to get the default. Possible values are:

nMultipleMax

Specifies the maximum number of barcodes to search. Pass 0 to read all barcodes in a specified search area.

rcSearch

Rectangle that contains the search area for the barcodes.

bUseRgn

Flag that indicates whether to use the region when searching. Possible values are:

BarColor

BarCodeColor structure, which contains the bars and space colors to search for barcodes.

pfnCallback

Optional callback function to be called when a barcode symbolgoy is decoded correctly. If you do not provide callback function, use NULL as the value of this parameter. If you do provide callback function, use the function pointer as the value of this parameter. The callback function must adhere to the function prototype described in BARCODEREADCALLBACK Function.

pUserData

Void pointer that you can use to pass one or more additional parameters that the help callback function needs. To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. If the additional parameters are not needed, you can pass NULL in this parameter.

Comments

NOTE: Type RSS14 is now GS1 Databar. All references to RSS14 now refer to GS1 Databar.

pBARCODEREADOPT is a pointer to an BARCODEREADOPT structure. Where a function parameter type is pBARCODEREADOPT, you can declare a BARCODEREADOPT variable and pass the variable's address in the parameter. Declaring a pBARCODEREADOPT variable is necessary only if your program requires a pointer.

When the BARCODE_USECOLORS flag is set, then this function will use the BarColor member, otherwise the LBarCode::Read function will ignore it and use the default colors of black for bars and white for spaces are used.

Using colors does not apply for 1 bit per pixel images.

The BARCODE_USECOLORS flag is used with all barcode kinds.

The BARCODE_RETURNCHECK flag used only with reading linear barcodes.

The BARCODE_RRESIZESMALL1D flag should be used when reading 1D symbols that have small width per module especially if the image has a low dpi value.

The smallest Data Matrix symbol size is 40 pixels by 40 pixels. It can be read using BARCODE_DM_READ_SMALL since this enables the reading of Data Matrix symbols that are between 20 to 40 pixels in size.

When reading barcodes from poor quality images, use BARCODE_APPLY_PREPROCESSING to enable image segmentation and advanced image preprocessing during barcode recognition.

When reading 2D barcodes, LEADTOOLS can perform internal auto preprocessing using BARCODE_DOUBLE_PASS on the image and try again if the engine cannot detect the barcode required. But this may take extra processing which will increase the barcode detection time. Hence, it is not recommended to always have it enabled except in certain situations:

• The application is reading barcodes of this type exclusively. For example, a dedicated PDF417 reader. Here, always reading the barcode is more important than recognition speed.

• The application uses barcode detection on a server. In this case, the time spent on the actual barcode detection is most probably less than the time required to send the image to the server and get the results back due to network latency. Thus, it makes sense to turn this feature on in this situation.

• The images provided may have a small resolution (DPI) or known to come from a source that does not always provide clean images. For example, a Fax machine or a Scanner. Enabling double pass here ensures that you can read the barcodes regardless on the quality of the input image.

The LEADTOOLS Barcode Demo leaves the option disabled by default.

When the ulFlags member value is set to BARCODE_RETURN_FOUR_POINTS flag, the BARCODEDATA.rcBarLocation member will be updated with the four-point corner encoded values.

Before using the four-point corner encoded values, they must be decoded.

The following example shows how to decode the four-point corner values:

POINT p1, p2, p3, p4;   
int nStartX = BarCodeData.rcBarLocation.left;   
int nStartY = BarCodeData.rcBarLocation.top;   
int nWidth = BarCodeData.rcBarLocation.right - nStartX;   
int nHeight = BarCodeData.rcBarLocation.bottom - nStartY;   
p1.x = (nStartX & 0xffff);   
p1.y = (nStartX >> 16);   
p2.x = (nStartY & 0xffff);   
p2.y = (nStartY >> 16);   
p3.x = (nWidth & 0xffff);   
p3.y = (nWidth >> 16);   
p4.x = (nHeight & 0xffff);   
p4.y = (nHeight >> 16); 

Usage

• LBarCode::GetReadOptions
• LBarCode::SetReadOptions