QThread and Error Access violation

? Offline

Hello everybody :)

I have a problem with QThread when i want change my form objects status during thread processing.

Now see these are my codes...

this is my mainwindows.h

@
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QObject>
#include <QThread>

class MyThread : public QThread
{
Q_OBJECT

public:
MyThread(QObject *parent = 0);
void run();

signals:
void MyThreadSignal();

};

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public:
void _send(QString _title, QString _message);

public slots:
void MyThreadSlot();

private:
Ui::MainWindow *ui;
myThread *onethread;
};

#endif // MAINWINDOW_H

@

and this is mainwindows.cpp

@
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QThread>
#include <QDebug>

/* ****** Thread part ****** */
myThread::myThread(QObject *parent)
: QThread(parent){}

void MyThread::run()
{
//Run my function
_send();
}

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::on_BUTTON_SEND_clicked()
{

ui->tabWidget->setDisabled(true); // Disable my tabWidget

onethread = new MyThread(this);
connect(onethread, SIGNAL(MyThreadSignal()), this, SLOT(_send()));
onethread->start(QThread::NormalPriority);

}

void MainWindow::_send()

{

ui->tabWidget->setDisabled(false); // Enable my tabWidget // Error in here

}

@

Why when I run thread process I can't set enable status for tabWidget ? without thread anything is good work but by thread no ! why ? can anyone help me for solve this problem? :)

Thanks you.

SGaist

Hi,

Are you trying to call MainWindow::_send directly from MyThread::run ?

? Offline

[quote author="SGaist" date="1407411703"]Hi,

Are you trying to call MainWindow::_send directly from MyThread::run ?[/quote]

hi SGaist how are you ?
Thanks for your reply..

By MainWindow::_send(); i get this error :

@

error: cannot call member function 'void MainWindow::_send()' without object
MainWindow::_send();
^
@

SGaist

You can't call a function from another class.

Also, you have a signature mismatch between your header and implementation.

What exactly are you trying to achieve ?

? Offline

[quote author="SGaist" date="1407412316"]You can't call a function from another class.

Also, you have a signature mismatch between your header and implementation.

What exactly are you trying to achieve ?
[/quote]

Where is my mismatch can u show me?
I want to change my tabWidget status from disable to enable after Thread processing...

SGaist

@
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public:
void _send(QString _title, QString _message); << here
}; @

@
void MyThread::run()
{
//Run my function
_send(); << there
}
@

? Offline

[quote author="SGaist" date="1407442699"]@
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public:
void _send(QString _title, QString _message); << here
}; @

@
void MyThread::run()
{
//Run my function
_send(); << there
}
@

[/quote]

Hi again...

I Chaged to

@
public:
void _send();
@

and

@
void MainWindow::_send()

{

ui->tabWidget->setDisabled(false);

};
@

and

@
void MyThread::run()
{
//Run my function
//MainWindow::_send();

MainWindow *II;
    II->_send();

}
@

but not working !
Error :

@
QObject::connect: No such slot MainWindow::_send() in ..\untitled15\mainwindow.cpp:40
QObject::connect: (receiver name: 'MainWindow')
@

msue

try to change "public" into "public slots" before your send function.

? Offline

[quote author="msue" date="1407481533"]try to change "public" into "public slots" before your send function.[/quote]

Unfortunately ...
The program has unexpectedly finished.
..\untitled15.exe crashed

:(

SGaist

That's normal, MainWindow *ll is uninitialized.

Anyway, you should not access MainWindow from your thread, just emit the signal you connected earlier.

Also it's seems you are new to C++, I'd recommend getting a good book about it

? Offline

[quote author="SGaist" date="1407483129"]That's normal, MainWindow *ll is uninitialized.

Anyway, you should not access MainWindow from your thread, just emit the signal you connected earlier.

Also it's seems you are new to C++, I'd recommend getting a good book about it[/quote]

Can you show me a good document or book about this question ?!
I mean how to update GUI in Thread process.

Thank you.

SGaist

Qt's own documentation and examples e.g. the Mandelbrot example

? Offline

[quote author="SGaist" date="1407484062"]Qt's own documentation and examples e.g. the Mandelbrot example[/quote]

Thank you for your helping... i try to read it :)