Extreme confusing problem

PandaBoy

Hello, guys, I am trying to create an icon in tray.
The problem I met is rather strange.
I added my icon.png to a .qrc file and loaded the image from that. The Image itself never shows up.
Even if I copied the path or url given by qt creator itself, it just didn't work.
However, when I moved my icon.png to a location on my disk say "c://" it worked.

.pro file:
RESOURCES += \
Ima.qrc

.qrc file:
<RCC>
<qresource prefix="/new">
<file>icon.png</file>
</qresource>
</RCC>

testing code:
QGraphicsScene scene;
QGraphicsView view(&scene);
QGraphicsPixmapItem item(QPixmap(":/new/icon.png"));
/* qrc:/new/icon.png won't work either */
scene.addItem(&item);
view.show();

real code:
QIcon icon("C:\icon.png");
trayIcon->setIcon(icon);
setWindowIcon(icon);
trayIcon->show();
/* it works */

"C:\icon.png" directory works fine for both testing code and real code.

Thank you guys! I have already solved it.
It turns out that Q_INIT_RESOURCE(***); is truly needed.
And Unlinked problem when I added this line can be solved in following operation:

Make your "***" in the parentheses is the name of your .qrc file and correctly typed
2.Clean your project
3.Qmake your project
4.Run again and problem solved.

mcosta

Hi and welcome to devnet,

is your png file in the same directory of the .qrc??

PandaBoy

@mcosta
Yes.And I tried creating a folder in the same directory of .qrc file and move png to that folder. It didn't work

mcosta

Have you tried to use the resource icon in your real code??

To show an Item in a GraphicsView you have to set correctly GraphicsScene rect and the view

This code

ui->label->setPixmap(QPixmap(":/images/image.png"));

works well for me using the resource

<RCC>
    <qresource prefix="/images">
        <file>image.png</file>
    </qresource>
</RCC>

Rondog

Maybe the Q_INIT_RESOURCE(<qrc file name>) is missing from main?

int main(int argc, char *argv[])
{
    Q_INIT_RESOURCE(application);
    QApplication app(argc, argv);
   
    MainWindow mainWin;
    mainWin.show();
    return app.exec();
}

mcosta

@Rondog Q_INIT_RESOURCE is not required if you add the resource file in the .pro file

PandaBoy

@Rondog Thank you Randog, But it is not the problem.
I think that this line might be unnecessary. But you brought this up, I have another question for this line.
I have tried this even before I asked here. And when I add this line to my main.cpp, It told me " LNK2019 unresolved symbol".
There is an example in Qt document using this line, and I had the exact same libraries included.

Note:

resource file has been included in .pro file.
Q_INIT_RESOURCE(Ima); /* name of my qrc file is Ima.qrc now*/

PandaBoy

@mcosta Yes, I have. It doesn't work.

mcosta

@PandaBoy could you attach your project? (the whole project directory)

Rondog

The unresolved linker error will occour if the name inside the macro Q_INIT_RESOURCE cannot be found.

I was not aware that this wasn't required, I tried it and sure enough it worked without it. It is interesting that when you did add it you ended up with a link error which means it can't be loaded (I have always added this line inside of main and get this error when I don't set the name properly).

From a sample program I have the following (that does work):

// qrc file =====================
<!DOCTYPE RCC><RCC version="1.0">
	<qresource prefix="/gui">
		<file>autocapture.png</file>
	</qresource>
</RCC>

// pro file =====================
// note:  I put all the resources in a folder called 'res'
RESOURCES += res/autocapture.qrc

// usage example =====================
	d_start_button->setIcon(QIcon(":/gui/autocapture.png"));

A couple of observations that might be helpful.

The resources line in the .PRO file ...

RESOURCES += \
Ima.qrc

... might be a problem. Why not this instead:

RESOURCES += Ima.qrc

The .qrc file is missing the first XML identification line (i.e. '<!DOCTYPE RCC>' ). Maybe the file is not recognized as a resource file without this line?

mcosta

Hi,

<!DOCTYPE RCC> is not needed.

You have to add Q_INIT_RESOURCE when you want to load resources not embedded in your application.

I'm not sure to understand; the simple icon example works or not??
Your app with QGraphicsScene??