decode_bar_code_rectangle2T_decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 (算子)

名称

decode_bar_code_rectangle2T_decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 — 解码矩形内的条形码符号。

签名

描述

算子 decode_bar_code_rectangle2decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 uses the bar code model specified by BarCodeHandleBarCodeHandleBarCodeHandleBarCodeHandlebarCodeHandlebar_code_handle to decode a bar code at a given position within the image ImageImageImageImageimageimage. BarCodeHandleBarCodeHandleBarCodeHandleBarCodeHandlebarCodeHandlebar_code_handle must be created with create_bar_code_modelcreate_bar_code_modelCreateBarCodeModelCreateBarCodeModelCreateBarCodeModelcreate_bar_code_model, its parameters can be set with set_bar_code_paramset_bar_code_paramSetBarCodeParamSetBarCodeParamSetBarCodeParamset_bar_code_param。The position of the bar code is given as an arbitrarily oriented rectangle. Contrary to find_bar_codefind_bar_codeFindBarCodeFindBarCodeFindBarCodefind_bar_code, where the decoding is preceded by a time consuming search for candidate regions, decode_bar_code_rectangle2decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 scans the provided region directly for bar codes. The rectangular region is defined by the parameters RowRowRowRowrowrow and ColumnColumnColumnColumncolumncolumn for the center, PhiPhiPhiPhiphiphi for the orientation and Length1Length1Length1Length1length1length_1 and Length2Length2Length2Length2length2length_2 for the half edge lengths (see gen_rectangle2gen_rectangle2GenRectangle2GenRectangle2GenRectangle2gen_rectangle2). The angle PhiPhiPhiPhiphiphi also determines the reading direction and is defined as the angle between the reading direction of the bar code and the horizontal image axis. The angle is positive in counter clockwise direction and is given in radians as in gen_rectangle2gen_rectangle2GenRectangle2GenRectangle2GenRectangle2gen_rectangle2。Note that the angle unit deviates from the conventions in get_bar_code_resultget_bar_code_resultGetBarCodeResultGetBarCodeResultGetBarCodeResultget_bar_code_result and set_bar_code_paramset_bar_code_paramSetBarCodeParamSetBarCodeParamSetBarCodeParamset_bar_code_param where angles are given in degrees. PhiPhiPhiPhiphiphi can be in the range of []. The reading direction is perpendicular to the bars of the bar code. Bar codes with a reading direction are also returned. Multiple regions for decoding can be given by supplying tuples for RowRowRowRowrowrow, ColumnColumnColumnColumncolumncolumn, PhiPhiPhiPhiphiphi, Length1Length1Length1Length1length1length_1 and Length2Length2Length2Length2length2length_2。

The rectangle should cover completely the bar code and the quiet zones. Regions that are too big will be decoded, if there is no disturbing pattern within these regions and the height (Length2Length2Length2Length2length2length_2) is small enough such that scanlines can be placed sufficiently dense. Rectangles that are too short in reading direction (Length1Length1Length1Length1length1length_1) cannot be decoded.

decode_bar_code_rectangle2decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 can be used if the position of the bar code is already known in advance. For example, the candidate regions found by find_bar_codefind_bar_codeFindBarCodeFindBarCodeFindBarCodefind_bar_code and get_bar_code_objectget_bar_code_objectGetBarCodeObjectGetBarCodeObjectGetBarCodeObjectget_bar_code_object could be reused with a different code type (see the following example).

Multiple bar code types can be specified for CodeTypeCodeTypeCodeTypeCodeTypecodeTypecode_type. See section Autodiscrimination for find_bar_codefind_bar_codeFindBarCodeFindBarCodeFindBarCodefind_bar_code。

Further aspects of the actual decoding are explained with the operator find_bar_codefind_bar_codeFindBarCodeFindBarCodeFindBarCodefind_bar_code。

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 在内部数据级别上自动并行化。

此算子支持取消超时和中断。

此算子修改后续输入参数的状态：

• BarCodeHandleBarCodeHandleBarCodeHandleBarCodeHandlebarCodeHandlebar_code_handle

在执行此算子时，若该参数值需在多个线程间使用，则必须对其访问进行同步。

参数

示例（HDevelop）

read_image (Image, 'barcode/ean13/ean1301.png')
create_bar_code_model ([], [], BHandle)
find_bar_code (Image, SymReg, BHandle, '2/5 Industrial', Dec)
if (|Dec| == 0)
*     A 2/5 Industrial code wasn't found. Try decoding an EAN-13 code.
    get_bar_code_object (CandReg, BHandle, 'all', 'candidate_regions')
    smallest_rectangle2 (CandReg, R, C, Phi, L1, L2)
    decode_bar_code_rectangle2 (Image, BHandle, 'EAN-13', R, C, Phi, \
                                L1, L2, Dec)
endif

结果

算子 decode_bar_code_rectangle2decode_bar_code_rectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2DecodeBarCodeRectangle2decode_bar_code_rectangle2 在给定的参数正确时返回值 2 ( H_MSG_TRUE )。否则，将抛出异常。

可能的前趋

create_bar_code_modelcreate_bar_code_modelCreateBarCodeModelCreateBarCodeModelCreateBarCodeModelcreate_bar_code_model, set_bar_code_paramset_bar_code_paramSetBarCodeParamSetBarCodeParamSetBarCodeParamset_bar_code_param, smallest_rectangle2smallest_rectangle2SmallestRectangle2SmallestRectangle2SmallestRectangle2smallest_rectangle2

可能的后继

get_bar_code_resultget_bar_code_resultGetBarCodeResultGetBarCodeResultGetBarCodeResultget_bar_code_result, get_bar_code_objectget_bar_code_objectGetBarCodeObjectGetBarCodeObjectGetBarCodeObjectget_bar_code_object, clear_bar_code_modelclear_bar_code_modelClearBarCodeModelClearBarCodeModelClearBarCodeModelclear_bar_code_model

替代

find_bar_codefind_bar_codeFindBarCodeFindBarCodeFindBarCodefind_bar_code

另见

gen_rectangle2gen_rectangle2GenRectangle2GenRectangle2GenRectangle2gen_rectangle2

模块

条形码

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