Issue with threading and opencv
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@jsulm : Hello i have implemented the save image function in a slot as suggested by you.
But the problem is that the image is not being saved. I would like to share the given code:signals:
void signalSaveImage(cv::Mat,String row,String column);
slots:
public slots:
void saveImage(Mat finalImage,String row, String column);
Slot Definition:void MainWindow::saveImage(Mat finalImage, String row, String column) { cout<<"Inside image save function"<<endl; cout<<"Row"<<row<<endl; cout<<"Column"<<column<<endl; String imagePath = "D:/testN/" String imageFormat = ".bmp"; try { cv::imwrite(imagePath+row+"_"+column+imageFormat,finalImage); } catch (cv::Exception& ex) { fprintf(stderr, "Exception in saving image: %s\n", ex.what()); } fprintf(stdout, "Saved PNG file with alpha data.\n"); cout<<"\n Entering inside save mutex"<<endl; cout<<"\n Completed image save function"<<endl; }Signal to slot connection:
connect(this,SIGNAL(signalSaveImage(cv::Mat,String,String)),this,SLOT(saveImage(Mat,String,String)),Qt::QueuedConnection);MainWindow.cpp
Emitting signal to save image:
emit signalSaveImage(image,to_string(row),to_string(column));But my problem is that my images are not being saved.
@Kira said in Issue with threading and opencv:
QueuedConnection
forces a copy of the arguments, The MetaSystem doesn't know the type cv::Mat -> can't be transmitted via QueuedConnection.
Check your console output you should have warning of unknown metatyps (declare and/or register)
Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct
Q: What's that?
A: It's blue light.
Q: What does it do?
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@Kira said in Issue with threading and opencv:
QueuedConnection
forces a copy of the arguments, The MetaSystem doesn't know the type cv::Mat -> can't be transmitted via QueuedConnection.
Check your console output you should have warning of unknown metatyps (declare and/or register)
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@J.Hilk : I have registered it.
#include "mainwindow.h"
#include <QApplication>int main(int argc, char *argv[])
{
qRegisterMetaType< cv::Mat >("cv::Mat");
QApplication a(argc, argv);
MainWindow w;
w.show();return a.exec();}
the data goes most likely out of scope, as the copy constructor of cv::Mat does actually no coping
I had the same issues in my time with opencv.
ended up converting it to a Image before transferring it from the opencv thread to the normal one.
Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct
Q: What's that?
A: It's blue light.
Q: What does it do?
A: It turns blue. -
the data goes most likely out of scope, as the copy constructor of cv::Mat does actually no coping
I had the same issues in my time with opencv.
ended up converting it to a Image before transferring it from the opencv thread to the normal one.
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@J-Hilk : will try and also i tried to run the program in debug mode and getting the following error.
Debugger redirects to following line of file of ostream:
// MANIPULATORS
template<class _Elem,
class _Traits> inline
basic_ostream<_Elem, _Traits>&
__CLRCALL_OR_CDECL endl(basic_ostream<_Elem, _Traits>& _Ostr)
{ // insert newline and flush stream
_Ostr.put(_Ostr.widen('\n'));
_Ostr.flush();
return (_Ostr);
}
And the program quits.
Can u please explain what may be the relevant reason for error -
@J-Hilk : will try and also i tried to run the program in debug mode and getting the following error.
Debugger redirects to following line of file of ostream:
// MANIPULATORS
template<class _Elem,
class _Traits> inline
basic_ostream<_Elem, _Traits>&
__CLRCALL_OR_CDECL endl(basic_ostream<_Elem, _Traits>& _Ostr)
{ // insert newline and flush stream
_Ostr.put(_Ostr.widen('\n'));
_Ostr.flush();
return (_Ostr);
}And the program quits.
Can u please explain what may be the relevant reason for error@Kira Please post the stack trace after crash
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@jsulm : This is the only thing which i see after crash with exception triggered.
Is there any other way to do so@Kira In QtCreator if you start with debugger you will have a stack trace
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@Kira Yes. Now you need to go from top to bottom until you hit first source code file from your project and check it at the line mentioned in the stack trace.
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@Kira Yes. Now you need to go from top to bottom until you hit first source code file from your project and check it at the line mentioned in the stack trace.
@jsulm : I tried doing it but the error is expected to come after thread running >150 times which is making the debugging process very difficult.
I have also sample test case on github can you please go through it for any possible issues.
https://github.com/HackersSpirit/ImageProcessor -
@jsulm : I tried doing it but the error is expected to come after thread running >150 times which is making the debugging process very difficult.
I have also sample test case on github can you please go through it for any possible issues.
https://github.com/HackersSpirit/ImageProcessor@Kira said in Issue with threading and opencv:
150 times
you can tell a breakpoint to be ignored for a certain amount of time
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@jsulm : I tried doing it but the error is expected to come after thread running >150 times which is making the debugging process very difficult.
I have also sample test case on github can you please go through it for any possible issues.
https://github.com/HackersSpirit/ImageProcessor@Kira I actually suggested to go through the stack trace after crash from top to bottom. No break points needed for that.
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@Kira I actually suggested to go through the stack trace after crash from top to bottom. No break points needed for that.
@jsulm :
@Kira said in Issue with threading and opencv:@jsulm : Are you referring to this:
Please let me know in case of any issuesThis is the stack trace which i get posted earlier referring from line no 1. It does not point to line of code where program has a break.
But line 16 and 17 point to the line of the code.
Should i refer those line for particular cause of the program to break
Please do let me know if i getting something wrong -
@jsulm :
@Kira said in Issue with threading and opencv:@jsulm : Are you referring to this:
Please let me know in case of any issuesThis is the stack trace which i get posted earlier referring from line no 1. It does not point to line of code where program has a break.
But line 16 and 17 point to the line of the code.
Should i refer those line for particular cause of the program to break
Please do let me know if i getting something wrong@Kira Check your code in that source code at line 16 and 17.
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@jsulm :
Line 16 is pointing to following line in bold:
void ImageMapping::requestReWorkNew()
{
cout<<"Inside requestRework Newwwwwwwwww"<<endl;
const int sleep = 50;
int queueSize = queueImageName.size();
cout<<"Queue size Request Rework New: "<<queueSize<<endl;
if(queueImageName.size()!=0){
//Get the current image number from the list of images
mutex.lock();
_working = true;
_abort = false;
mutex.unlock();
cout<<"Emiting resume work"<<endl;
emit resumeWork();
}else{
cout<<"Signalling retrying"<<endl;emit retrying(); }}
This function is basically a slot triggered by following signal:
connect(imageMapping, SIGNAL(finished()), imageMapping, SLOT(requestReWorkNew()));
connect(imageMapping, SIGNAL(retrying()),imageMapping,SLOT(requestReWorkNew())); -
@jsulm :
Line 16 is pointing to following line in bold:
void ImageMapping::requestReWorkNew()
{
cout<<"Inside requestRework Newwwwwwwwww"<<endl;
const int sleep = 50;
int queueSize = queueImageName.size();
cout<<"Queue size Request Rework New: "<<queueSize<<endl;
if(queueImageName.size()!=0){
//Get the current image number from the list of images
mutex.lock();
_working = true;
_abort = false;
mutex.unlock();
cout<<"Emiting resume work"<<endl;
emit resumeWork();
}else{
cout<<"Signalling retrying"<<endl;emit retrying(); }}
This function is basically a slot triggered by following signal:
connect(imageMapping, SIGNAL(finished()), imageMapping, SLOT(requestReWorkNew()));
connect(imageMapping, SIGNAL(retrying()),imageMapping,SLOT(requestReWorkNew()));@Kira Are you sure this is the line? The actual line is mentioned in the "Line" column in the stack trace. So, it would be 2129.
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@jsulm :
Line 16 is pointing to following line in bold:
void ImageMapping::requestReWorkNew()
{
cout<<"Inside requestRework Newwwwwwwwww"<<endl;
const int sleep = 50;
int queueSize = queueImageName.size();
cout<<"Queue size Request Rework New: "<<queueSize<<endl;
if(queueImageName.size()!=0){
//Get the current image number from the list of images
mutex.lock();
_working = true;
_abort = false;
mutex.unlock();
cout<<"Emiting resume work"<<endl;
emit resumeWork();
}else{
cout<<"Signalling retrying"<<endl;emit retrying(); }}
This function is basically a slot triggered by following signal:
connect(imageMapping, SIGNAL(finished()), imageMapping, SLOT(requestReWorkNew()));
connect(imageMapping, SIGNAL(retrying()),imageMapping,SLOT(requestReWorkNew()));
