Cxcore错误处理和系统函数

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错误处理

在 OpenCV 中错误处理和 IPL (Image Processing Library)很相似。假如错误处理函数不返回错误代码，而是用CV_ERROR 宏调用 cvError 函数报错，按次序地，用 cvSetErrStatus 函数设置错误状态，然后调用标准的或者用户自定义的错误处理器(它可以显示一个消息对话框，写出错误日志等等, 参考函数 cvRedirectError, cvNulDevReport, cvStdErrReport, cvGuiBoxReport)。每个程序的线程都有一个全局变量，它包含了错误状态(一个整数值)。这个状态可以被 cvGetErrStatus 函数检索到。

有三个错误处理模式(参考 cvSetErrMode 和 cvGetErrMode):

Leaf: 错误处理器被调用以后程序被终止。这是缺省值。它在调试中是很有用的，当错误发生的时候立即产生错误信息。然而对于产生式系统后面两种方法可能会为他们提供更多的控制方式。
Parent: 错误处理器被调用以后程序不会被终止。栈被清空 (它用 C++ 异常处理机制完成写/输出--w/o)。当调用 CxCore 的函数 cvGetErrStatus 起作用以后用户可以检查错误代码。
Silent: 和 Parent 模式相似, 但是没有错误处理器被调用。

事实上, Leaf 和 Parent 模式的语义被错误处理器执行，上面的描述对 cvNulDevReport, cvStdErrReport. cvGuiBoxReport 的行为有一些细微的差别，一些自定义的错误处理器可能语义上会有很大的不同。错误处理宏

报错，检查错误等的宏

/* special macros for enclosing processing statements within a function and separating
   them from prologue (resource initialization) and epilogue (guaranteed resource release) */
#define __BEGIN__       {
#define __END__         goto exit; exit: ; }
/* proceeds to "resource release" stage */
#define EXIT            goto exit

/* Declares locally 函数 name for CV_ERROR() use */
#define CV_FUNCNAME( Name )  \
    static char cvFuncName[] = Name

/* Raises an error within the current context */
#define CV_ERROR( Code, Msg )                                       \
{                                                                   \
     cvError( (Code), cvFuncName, Msg, __FILE__, __LINE__ );        \
     EXIT;                                                          \
}

/* Checks status after calling CXCORE function */
#define CV_CHECK()                                                  \
{                                                                   \
    if( cvGetErrStatus() < 0 )                                   \
        CV_ERROR( CV_StsBackTrace, "Inner function failed." );      \
}

/* Provies shorthand for CXCORE function call and CV_CHECK() */
#define CV_CALL( Statement )                                        \
{                                                                   \
    Statement;                                                      \
    CV_CHECK();                                                     \
}

/* Checks some condition in both debug and release configurations */
#define CV_ASSERT( Condition )                                          \
{                                                                       \
    if( !(Condition) )                                                  \
        CV_ERROR( CV_StsInternal, "Assertion: " #Condition " failed" ); \
}

/* these macros are similar to their CV_... counterparts, but they
   do not need exit label nor cvFuncName to be defined */
#define OPENCV_ERROR(status,func_name,err_msg) ...
#define OPENCV_ERRCHK(func_name,err_msg) ...
#define OPENCV_ASSERT(condition,func_name,err_msg) ...
#define OPENCV_CALL(statement) ...

取代上面的讨论, 这里有典型的 CXCORE 函数和这些函数使用的样例。错误处理宏的使用

#include "cxcore.h"
#include <stdio.h>

void cvResizeDCT( CvMat* input_array, CvMat* output_array )
{
    CvMat* temp_array = 0; // declare pointer that should be released anyway.

    CV_FUNCNAME( "cvResizeDCT" ); // declare cvFuncName

    __BEGIN__; // start processing. There may be some declarations just after this macro,
               // but they couldn't be accessed from the epilogue.

    if( !CV_IS_MAT(input_array) || !CV_IS_MAT(output_array) )
        // use CV_ERROR() to raise an error
        CV_ERROR( CV_StsBadArg, "input_array or output_array are not valid matrices" );

    // some restrictions that are going to be removed later, may be checked with CV_ASSERT()
    CV_ASSERT( input_array->rows == 1 && output_array->rows == 1 );

    // use CV_CALL for safe function call
    CV_CALL( temp_array = cvCreateMat( input_array->rows, MAX(input_array->cols,output_array->cols),
                                       input_array->type ));

    if( output_array->cols > input_array->cols )
        CV_CALL( cvZero( temp_array ));

    temp_array->cols = input_array->cols;
    CV_CALL( cvDCT( input_array, temp_array, CV_DXT_FORWARD ));
    temp_array->cols = output_array->cols;
    CV_CALL( cvDCT( temp_array, output_array, CV_DXT_INVERSE ));
    CV_CALL( cvScale( output_array, output_array, 1./sqrt((double)input_array->cols*output_array->cols), 0 ));

    __END__; // finish processing. Epilogue follows after the macro.

    // release temp_array. If temp_array has not been allocated before an error occured, cvReleaseMat
    // takes care of it and does nothing in this case.
    cvReleaseMat( &temp_array );
}


int main( int argc, char** argv )
{
    CvMat* src = cvCreateMat( 1, 512, CV_32F );
#if 1 /* no errors */
    CvMat* dst = cvCreateMat( 1, 256, CV_32F );
#else
    CvMat* dst = 0; /* test error processing mechanism */
#endif
    cvSet( src, cvRealScalar(1.), 0 );
#if 0 /* change 0 to 1 to suppress error handler invocation */
    cvSetErrMode( CV_ErrModeSilent );
#endif
    cvResizeDCT( src, dst ); // if some error occurs, the message box will popup, or a message will be
                             // written to log, or some user-defined processing will be done
    if( cvGetErrStatus() < 0 )
        printf("Some error occured" );
    else
        printf("Everything is OK" );
    return 0;
}

Cxcore错误处理和系统函数

Wikipedia，自由的百科全书

目录

错误处理

GetErrStatus

SetErrStatus

GetErrMode

SetErrMode

Error

ErrorStr

RedirectError

cvNulDevReport cvStdErrReport cvGuiBoxReport

系统函数

Alloc

Free

GetTickCount

GetTickFrequency

RegisterModule

GetModuleInfo

UseOptimized

SetMemoryManager

SetIPLAllocators

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