(TBarcode2D_MicroPDF417)
Returns the check sum of a barcode text that will be encoded into a series of structured append symbols.
type
{ Defined in the pPDF417Com unit }
TPDF417_Option = (poIgnoreShiftBeforeECI, poFirst903TextAlphaLatch, poFirst904TextMixedLatch, po906TextAlphaLatch, po907TextAlphaLatch, po908TextAlphaLatch, po910TextAlphaLatch, po912TextAlphaLatch, po914TextAlphaLatch, po915TextAlphaLatch, poFirstFNC1MatchAI01, poMicroPDF417Explicit901);
{ Defined in the pPDF417Com unit }
TPDF417_Options = set of TPDF417_Option;
{ Defined in the pMicroPDF417 unit }
TMicroPDF417_Options = TPDF417_Options;
function GetCheckSum(Data: AnsiString; AllowEscape: Boolean; var InvalidIndex: Integer; Options: TMicroPDF417_Options = []): AnsiString; virtual;
The method returns the check sum of a barcode text that will be encoded into a series of structured append symbols. The value will be used in the structured append block, and the structured append block will be used by each symbol in the series of MicroPDF417 structured append symbols. See also the "Structured append" section in the "TBarcode2D_MicroPDF417" article.
Data: AnsiString; It's the original input text before division into the each symbol in the series of structured append symbols. It is of type AnsiString. The method is available only for the Delphi/C++ Builder 2009 or later.
For the Delphi/C++ Builder 2009 or later, you can use the method to caculate the check sum of a block of binary (bytes) data. Or specifies the barcode text in AnsiString format.
If you want to caculate the check sum of a block of binary (bytes) data under Delphi/C++ Builder 2007 or early, please use the GetCheckSum (Syntax 1) overloading method.
AllowEscape: Boolean; Specifies whether to allow users to insert the escape sequences to the Data parameter value, in order to place the function characters and additional control information. See also the "Escape sequences" section in the "TBarcode2D_MicroPDF417" article.
InvalidIndex: Integer; If there is any invalid character in the barcode text that is specified by the Data parameter, the parameter returns the position index of first invalid character, the index 1 denotes that the first character is invalid character. Otherwise, it returns the zero.
Options: TMicroPDF417_Options; The Options parameter is an advanced feature which allows low level control over data encoding. The parameter can be used to change the encoding algorithm and meanings of some fucntion codewords, in order to match the reader. The values that can be included in the Options parameter are defined in the pPDF417Com unit. See also the "Options" property article.
If the method succeeds, it returns the check sum value, it's a 16-bit word value, in decimal AnsiString format. And the InvalidIndex parameter returns zero. If the method fails, the InvalidIndex parameter returns a position index of first invalid character, it's an integer value greater than 0.
The result string can be directly used as the check sum in the structured append block. For example:
var
full_barcode, check_sum, structuredappend_block: string;
invalid_index: integer;
begin
full_barcode := '......';
check_sum := GetCheckSum(full_barcode, false, invalid_index, []);
if invalid_index > 0 then exit;
structuredappend_block := '\s[1,001287023,,5,2008-12-03 05:30:00,,USA,,' + check_sum + ']';
//.....
See also the "Sturctured append" section in the "TBarcode2D_MicroPDF417" article.
The overloading method is available only for the Delphi/C++ Builder 2009 or later.