我正在尝试将函数作为参数传递给另一个函数。 以下代码在没有使用类的情况下有效，但是当我用qt类尝试它时，会发生以下错误...
error: argument of type 'void (MainWindow::)(int, int, int, int, void*)'
does not match 'void (*)(int, int, int, int, void*)'
我的代码是
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv/cv.h>
#include <opencv/cvaux.h>
#include <opencv/highgui.h>
// for filelisting
#include <stdio.h>
#include <sys/file.h>
#include<io.h>
// for fileoutput
#include <string>
#include <fstream>
#include <sstream>
#include <dirent.h>
#include <sys/types.h>
using namespace std;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
roi_x0=0;
roi_y0=0;
roi_x1=0;
roi_y1=0;
numOfRec=0;
startDraw = 0;
window_name="<SPACE>add <B>save and load next <ESC>exit";
}
MainWindow::~MainWindow()
{
delete ui;
}
string MainWindow::IntToString(int num)
{
ostringstream myStream; //creates an ostringstream object
myStream << num << flush;
/*
* outputs the number into the string stream and then flushes
* the buffer (makes sure the output is put into the stream)
*/
return(myStream.str()); //returns the string form of the stringstream object
}
void MainWindow::on_mouse(int event, int x, int y, int flag, void *param)
{
if(event==CV_EVENT_LBUTTONDOWN)
{
if(!startDraw)
{
roi_x0=x;
roi_y0=y;
startDraw = 1;
} else {
roi_x1=x;
roi_y1=y;
startDraw = 0;
}
}
if(event==CV_EVENT_MOUSEMOVE && startDraw)
{
//redraw ROI selection
image2=cvCloneImage(image);
cvRectangle(image2,cvPoint(roi_x0,roi_y0),cvPoint(x,y),CV_RGB(255,0,255),1);
cvShowImage(window_name,image2);
cvReleaseImage(&image2);
}
}
void MainWindow::on_actionMark_Faces_triggered()
{
char iKey=0;
string strPrefix;
string strPostfix;
string input_directory;
string output_file;
input_directory ="E:/My/";
output_file ="pos.txt";
/* Get a file listing of all files with in the input directory */
DIR *dir_p = opendir (input_directory.c_str());
struct dirent *dir_entry_p;
if(dir_p == NULL) {
fprintf(stderr, "Failed to open directory %s\n", input_directory.c_str());
}
fprintf(stderr, "Object Marker: Input Directory: %s Output File: %s\n", input_directory.c_str(), output_file.c_str());
// init highgui
cvAddSearchPath(input_directory);
cvNamedWindow(window_name,1);
cvSetMouseCallback(window_name,on_mouse,NULL);
fprintf(stderr, "Opening directory...");
// init output of rectangles to the info file
ofstream output(output_file.c_str());
fprintf(stderr, "done.\n");
while((dir_entry_p = readdir(dir_p)) != NULL)
{
numOfRec=0;
if(strcmp(dir_entry_p->d_name, ""))
fprintf(stderr, "Examining file %s\n", dir_entry_p->d_name);
/* TODO: Assign postfix/prefix info */
strPostfix="";
//strPrefix=input_directory;
strPrefix=input_directory+dir_entry_p->d_name;
//strPrefix+=bmp_file.name;
fprintf(stderr, "Loading image %s\n", strPrefix.c_str());
if((image=cvLoadImage(strPrefix.c_str(),1)) != 0)
{
// work on current image
do
{
cvShowImage(window_name,image);
// used cvWaitKey returns:
// <B>=66 save added rectangles and show next image
// <ESC>=27 exit program
// <Space>=32 add rectangle to current image
// any other key clears rectangle drawing only
iKey=cvWaitKey(0);
switch(iKey)
{
case 27:
cvReleaseImage(&image);
cvDestroyWindow(window_name);
return;
case 32:
numOfRec++;
printf(" %d. rect x=%d\ty=%d\tx2h=%d\ty2=%d\n",numOfRec,roi_x0,roi_y0,roi_x1,roi_y1);
//printf(" %d. rect x=%d\ty=%d\twidth=%d\theight=%d\n",numOfRec,roi_x1,roi_y1,roi_x0-roi_x1,roi_y0-roi_y1);
// currently two draw directions possible:
// from top left to bottom right or vice versa
if(roi_x0<roi_x1 && roi_y0<roi_y1)
{
printf(" %d. rect x=%d\ty=%d\twidth=%d\theight=%d\n",numOfRec,roi_x0,roi_y0,roi_x1-roi_x0,roi_y1-roi_y0);
// append rectangle coord to previous line content
strPostfix+=" "+IntToString(roi_x0)+" "+IntToString(roi_y0)+" "+IntToString(roi_x1-roi_x0)+" "+IntToString(roi_y1-roi_y0);
}
else
//(roi_x0>roi_x1 && roi_y0>roi_y1)
{
printf(" hello line no 154\n");
printf(" %d. rect x=%d\ty=%d\twidth=%d\theight=%d\n",numOfRec,roi_x1,roi_y1,roi_x0-roi_x1,roi_y0-roi_y1);
// append rectangle coord to previous line content
strPostfix+=" "+IntToString(roi_x1)+" "+IntToString(roi_y1)+" "+IntToString(roi_x0-roi_x1)+" "+IntToString (roi_y0-roi_y1);
}
break;
}
}
while(iKey!='b');
{
// save to info file as later used for HaarTraining:
// <rel_path>\bmp_file.name numOfRec x0 y0 width0 height0 x1 y1 width1 height1...
if(numOfRec>0&&iKey=='b')
{
//append line
/* TODO: Store output information. */
output << strPrefix << " "<< numOfRec << strPostfix <<"\n";
cvReleaseImage(&image);
}
else
{
fprintf(stderr, "Failed to load image, %s\n", strPrefix.c_str());
}
}
}}
output.close();
cvDestroyWindow(window_name);
closedir(dir_p);
}
错误发生在
行 cvSetMouseCallback(window_name,on_mouse,NULL);
答案 0 :(得分：1)
成员函数与常规函数不同（因为它们必须传入一个额外隐藏的'this'参数）。
这就是为什么它说：
void (MainWindow::)(int, int, int, int, void*)
不匹配：
void ()(int, int, int, int, void*)
MainWindow :: 部分非常重要。
如果您使用的是C ++ 11，则可以使用std :: function和std :: bind，它可以工作（参见this question）。静态成员函数也可以工作，因为静态成员函数也没有 this 指针，并且表现得像常规函数（但在命名空间中，并且具有私有成员访问权限）。
答案 1 :(得分：0)
回调方法必须是static和public（或非成员函数）。正如您所知，如果它是非成员函数，它会起作用，但如果它是非静态方法则会出错。您应该将MainWindow::on_mouse定义为：
static void MainWindow::on_mouse(int event, int x, int y, int flag, void *param)
答案 2 :(得分：0)
这不是一个罕见的问题。解决方案是使用包装函数：
static void MainWindow::on_mouse_wrapper(int event, int x, int y, int flag, void *param)
{
MainWindow* self = reinterpret_cast<MainWindow*>(param);
self->on_mouse(event, x, y, flag, NULL);
}
然后编辑
cvSetMouseCallback（window_name，on_mouse，NULL）;
为：
cvSetMouseCallback（window_name，on_mouse，这一点）;