Passing Pixmaps between MainWindow and Dialog

[wysota]

No, it's fine. You can check if the resulting makefile has proper flags, if you want to be sure. I really suggest you try stepping through the code from within the debugger.

[ramstormrage]

EDIT: Sorry, I stepped through the program, I found that the program halts somewhere within this function.

void brDialog::createImage(QImage &imag)
{
beforeLabel->setPixmap(QPixmap::fromImage(imag));
imagafterRGB = fileHandler.convertToRGBImage(imag);

//imagafter = fileHandler.convertToQImage(imagafterRGB);
afterLabel->setPixmap(QPixmap::fromImage(imagafter));
}


DOUBLE_EDIT:
Hello wysota,

I traced the program for a while and I experimented on different codes, and I found that the QImage image object from a while back really gets destroyed if i dont reinitialize it with QImage image(fileName) before I pass it to brDialog::createImage()

Now the problem is why? And is there another way to avoid this without reinitializing the image object?

void MainWindow::adjustBrightness()
{	
	brDialog dialog(this);
	//QImage image(fileName);         <-- can I avoid this or maybe I dont have a choice?
	dialog.createImage(image);
	dialog.exec();
}

void MainWindow::adjustBrightness()
{	
	brDialog dialog(this);
	//QImage image(fileName);         <-- can I avoid this or maybe I dont have a choice?
	dialog.createImage(image);
	dialog.exec();
}

To copy to clipboard, switch view to plain text mode 

Thank you for your patience..

[wysota]

Find out where you lose your image. It's certainly somewhere before adjustBrightness is called. Currently you don't "reinitialize" the image but create a local variable with the same name. If you do the same elsewhere then simply your member variable "image" never gets initialized.

[ramstormrage]

If you do the same elsewhere then simply your member variable "image" never gets initialized.

So that means its not correct to use QImage image(QString fileName) whenever I need to pass images to dialogs?

Is there another way to "permanently" initialize a QImage object from a file?

EDIT:
Hmm, I cant seem to find where in the code does the image object get lost, you see, I tried to clear and repaint the image on QLabel imageLabel until the end of MainWindow:pen(), and it still exists.

And then I tried to repaint the image inside the below function, just to try if image is still valid, and it is..

void MainWindow::closeImage()
{
	imageLabel->clear();
	closeAction->setEnabled(false);
        imageLabel->setPixmap(QPixmap::fromImage(image));
}

void MainWindow::closeImage()
{
	imageLabel->clear();
	closeAction->setEnabled(false);
        imageLabel->setPixmap(QPixmap::fromImage(image));
}

To copy to clipboard, switch view to plain text mode 

Now in my current project, these are the only functions inside the mainwindow.cpp file:
1. constructor
2. createMenus()
3. createActions()
4. open()
5. closeImage()
6. adjustBrightness()

I cant seem to find where image gets lost.

[wysota]

So that means its not correct to use QImage image(QString fileName) whenever I need to pass images to dialogs?

Yes, that's correct - it's incorrect.

Is there another way to "permanently" initialize a QImage object from a file?

Substitute

QImage image(filename)

QImage image(filename)

To copy to clipboard, switch view to plain text mode 

with

image = QImage(filename);

image = QImage(filename);

To copy to clipboard, switch view to plain text mode 

[ramstormrage]

Finally!!

After 25 posts, we got the correct code! Thanks for the help.. I cant thank you enough..
Haha!
Now, to do something about this blasted HEAP problems Ive been getting..

[ramstormrage]

Ok heap problems gone.

I forgot to ask this earlier but how to do I pass the modified image back to the MainWindow?
I created a method in MainWindow that accepts the modified image, but how do I call it from the dialog?

[wysota]

Oh come on, man. None of your problems are related to Qt - every problem you have is about C++ and code design. We are not here to teach you C++! Try making a method similar to the one I suggested in my very first post in this thread (or a second one, I don't remember) just going the other way round.

[ramstormrage]

Ok thank you very much wysota, I learned plenty of stuff.

Anyways, for the sake of other people that'll possibly view this thread, here's a possible solution.

void MainWindow::adjust()
{	
	adjustDialog dialog(this);		//Invoke modal Adjust Brightness Dialog
	dialog.createImage(image);          //Pass current image object to dialog
	if (dialog.exec()){
		image = dialog.submitImg();	//Overwrite current image with mod. image 
		refreshImage();
	}
}
 
QImage adjustDialog::submitImg()
{
	return ModifiedQImageObject;       //Returns modified image to MainWindow
}

void MainWindow::adjust()
{	
	adjustDialog dialog(this);		//Invoke modal Adjust Brightness Dialog
	dialog.createImage(image);          //Pass current image object to dialog
	if (dialog.exec()){
		image = dialog.submitImg();	//Overwrite current image with mod. image 
		refreshImage();
	}
}

QImage adjustDialog::submitImg()
{
	return ModifiedQImageObject;       //Returns modified image to MainWindow
}

To copy to clipboard, switch view to plain text mode