who can tell me ? I use directshow and wia but don't find the method
Why don't you use the OpenCV?
main.cpp
int main(int argc, char** argv) {
CvCapture* capture = cvCaptureFromCAM(0);
int index = 0;
while(cvGrabFrame(capture)) {
/*Get webcam image!*/
IplImage *camImg = cvRetrieveFrame(capture);
/*Save the image to the disk!*/
string fileName = "tmp/" + int2str(index) + ".jpg";
cvSaveImage(fileName.c_str(), screenShotImg);
index++;
int key = cvWaitKey(10);
if(key == 27) {
break;
}
}
cvReleaseCapture(&capture);
return 0;
}
TypeConvert.cpp
#include "TypeConvert.h"
#include <iostream>
#include <sstream>
string int2str(int &num) {
string emptyStr;
stringstream ss(emptyStr);
ss << num;
return ss.str();
}
Related
The following code use writeCharacters with small buffer size to writing the content of big file, but it seems it only works when writing the content to a xml file, but writeCharacters() will crash when writting the content of a big file to QBuffer, any solution? Thanks.
env: qt opensource 4.8.7; Visual Studio 2010; Windows 10;
big file: https://1drv.ms/u/s!Ap_EAuwC9QkXijbujBQcQk4Hat_O?e=KemgUY
#include <QtCore/QCoreApplication>
#include <QFile>
#include <QXmlStreamWriter>
#include <QBuffer>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QByteArray mContentBuffer;
QByteArray arr;
int pos, filesize;
QFile file("C:\\Work\\bigfile.xar"); //Szie: 300Mb
if(!file.open(QFile::ReadOnly))
{
return -1;
}
mContentBuffer = file.readAll();
file.close();
//QFile profile("C:\\Work\\profile.xml");
//if(!profile.open(QFile::WriteOnly|QFile::Truncate))
//{
// return -1;
//}
QBuffer buffer;
buffer.open(QBuffer::ReadWrite);
QXmlStreamWriter stream(&buffer);
stream.setAutoFormatting(true);
stream.writeStartDocument();
stream.writeStartElement("Profile");
//stream.writeTextElement("Content", mContentBuffer.toBase64());
stream.writeStartElement("Content");
pos = 0;
filesize = mContentBuffer.size();
while(pos<filesize){
arr = mContentBuffer.mid(pos, 2000000);
stream.writeCharacters(arr.toBase64());
pos+=arr.size();
}
stream.writeEndElement();
stream.writeEndElement(); // Profile
stream.writeEndDocument();
return 0;
}
Here is the goal for writing a big file into a QBuffer.
bool profileModified()
{
bool result = true;
QFile profile("C:\\Work\\profile.xml");
if(profile.exists())
{
QBuffer buffer;
buffer.open(QBuffer::ReadWrite);
QXmlStreamWriter stream(&buffer);
exportProfile(stream);
profile.open(QFile::ReadOnly);
QByteArray profileArr = profile.readAll();
buffer.seek(0);
QByteArray bufferArr = buffer.buffer();
result = (array_compare(profileArr, bufferArr) != 0);
profile.close();
}
return result;
}
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#define MALLOC(p,s) {\
if (!((p) = malloc(s))) { \
fprintf(stderr, "insufficient memory");\
exit(EXIT_FAILURE);\
}\
}
#define IS_EMPTY(first) (!first)
typedef struct listNode* listPointer;
typedef struct listNode {
int data;
listPointer link;
}listNode;
void printList(listPointer first);
int main(void)
{
int x;
int tmpData;
listPointer first = NULL;
listPointer tmpLink = NULL;
FILE* fp = NULL;
if (!(fp = fopen("in.txt", "r"))) {
fprintf(stderr, "cannot open the file");
exit(EXIT_FAILURE);
}
while (!feof(fp)) {
fscanf(fp, "%d", &tmpData);
MALLOC(tmpLink, sizeof(listNode));
if (IS_EMPTY(first)) {
MALLOC(first, sizeof(listNode));
*tmpLink = *first;
}
tmpLink->data = tmpData;
tmpLink = tmpLink->link;
}
printList(first);
}
void printList(listPointer first)
{
for (; first; first = first->link) {
printf("%d ", first->data);
}
printf("\n");
}
We know that we can implement the insert function.
But I'm really curious about why this doesn't work.
What "first" refers to and what "tmpLink" refers to is the same
After implementing the link list while updating tmpLink,
I'm going to use "first" to print later.
I've spent almost a day just thinking about this, and I've tried debugging it, but I don't know why.
I am trying to pass an array of integer to other program and accept that from *argv. Then sort the array and print that from initial program. But I can not accept the pointer of the array and work with it. (can't even compile sort.c)
#include<stdio.h>
int main(int argc, char *argv[])
{
int arr = argv[1];
int temp = 0;
int length = sizeof(arr);
//Sort the array in descending order
for (int i = 0; i < length; i++) {
for (int j = i+1; j < length; j++) {
if(arr[i] < arr[j]) {
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
}
}
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(int argc, char *argv[])
{
int length = args-1;
int arr[length];
for(int i=0;i<length,i++)
{
arr[i]=argv[i+1];
}
int *p=arr
pid_t pid=fork();
if (pid==0) {
execv("sort",p);
}
else {
}
return 0;
}
wanting to ask how to change this pass by reference into pass by pointer, cause some of my school works need pass by pointer and i doesn't really understand how to modified this code using pass by pointer
void convert(string &s){
for (int i =0; i<s.length(); i++){
s[i] = toupper(s[i]);
}
}
int main(){
string name;
cout<<"Enter your name"<<endl;
getline(cin,name);
convert(name);
cout<<name<<endl;
return 0;
}
First of all, there are some minor errors in the code.
Inlcude necessary headers.
Use std:: namespace prefix.
#include <iostream>
#include <string>
#include <cctype>
void convert(std::string &s){
for (int i =0; i < s.length(); i++){
s[i] = std::toupper(s[i]);
}
}
int main(){
std::string name;
std::cout << "Enter your name: ";
std::getline(std::cin, name);
convert(name);
std::cout << name << std::endl;
return 0;
}
Using pointer version?
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cctype>
#define SIZE 100
void convert(char *s, size_t size){
for (int i =0; i < size; i++){
s[i] = std::toupper(s[i]);
}
}
int main(){
char name[SIZE];
std::cout << "Enter your name: ";
std::fgets(name, SIZE, stdin);
convert(name, strlen(name));
std::cout << name << std::endl;
return 0;
}
Another version using pointers
#include <iostream>
#include <string>
#include <cctype>
void convert(std::string *s){
for (int i =0; i < s -> length(); i++){
(*s)[i] = std::toupper((*s)[i]);
}
}
int main(){
std::string *name = new std::string();
std::cout << "Enter your name: ";
std::getline(std::cin, *name);
convert(name);
std::cout << *name << std::endl;
delete name;
return 0;
}
I have a class ClientWindow. I have created several instances of it and appended the their pointers to a a list. If i try to show any of the windows however, I get "Segmentation fault (core dumped)" I keep the list of windows in a class called controller.
Here is my controller header file:
#ifndef CONTROLLER_H
#define CONTROLLER_H
#include "clientwindow.h"
class Controller
{
public:
Controller();
void createClients(int num);
void showWindows();
private:
QList<ClientWindow*> clWList;
int size;
};
#endif // CONTROLLER_H
this is the cpp file:
#include "controller.h"
Controller::Controller()
{
}
void Controller::createClients(int num)
{
size = num;
for(int i = 0; i < size; i++)
{
ClientWindow cw;
clWList.append(&cw);
}
}
void Controller::showWindows()
{
for(int i = 0; i < size; i++)
{
ClientWindow* cw = clWList.at(0);
cw->show();
}
}
this is my main:
#include <QtGui/QApplication>
#include "clientwindow.h"
#include "controller.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
// ClientWindow w;
// w.show();
QString temp = argv[1];
bool ok;
int tempI = temp.toInt(&ok, 10);
Controller c;
c.createClients(tempI);
c.showWindows();
return a.exec();
}
This is where it goes wrong:
for(int i = 0; i < size; i++)
{
ClientWindow cw;
clWList.append(&cw);
}
A local variable cw is created on the stack in each iteration. It is deallocated at the end of each iteration. Meaning the data is gone. So you end up storing pointers pointing to junk.
Calling a member function of a junk typically results in crash. :) Do this instead:
for(int i = 0; i < size; i++)
{
ClientWindow * cw = new ClientWindow();
clWList.append(cw);
}
You'll have to go through the list and delete the objects after you are done with them.