QResource::registerResource with rccData instead rccFileName

LazyT

Hello

in my app I use QResource::registerResource in the rccFileName variant without problems.

However, I don't understand the rccData variant.

As far as I understood I can pass a RCC binary file from memory. How should that work?

A RCC file starts with "qres" followed by 0x00 4 times and then the data.

Is anything after the first 0 not ignored? How would the function know when the resource ends?

Can someone please explain this?

Thanks...

Christian Ehrlicher

@LazyT said in QResource::registerResource with rccData instead rccFileName:

QResource::registerResource(ba.constData());

registerResource() takes a const uchar *. You're passing a const char * which is not automatically convertible to a const uchar * but instead implicitly converted into a QString because you did not define QT_NO_CAST_FROM_ASCII which you should to avoid such errors.

Christian Ehrlicher

Simply read the content of your resource into a QByteArray and pass QByteArray::constData() to registerResource(). The internal logic knows how long the resource data is.

LazyT

Thanks for your answer, but this doesn't work.

For example:

QResource rcc(":/rcc/icons.rcc");
QByteArray ba = rcc.uncompressedData();
qDebug() << rcc.isValid() << QResource::registerResource(ba.constData());

Result: true false

Christian Ehrlicher

@LazyT said in QResource::registerResource with rccData instead rccFileName:

but this doesn't work.

Because you have to pass the content of the resource file - read it with QFile. It's meant to deal with external resource files.

LazyT

Makes no difference.

QResource and QFile shows the content of the RCC file, but register fails.

Christian Ehrlicher

Please show your code. How did you create the external resource file?

LazyT

Thanks for your patience.

The RCC was created with

rcc --binary icons.qrc -o icons.rcc

contains SVGs and works fine with the rccFileName variant.

QFile rcc("/tmp/icons.rcc");

if(rcc.open(QIODevice::ReadOnly))
{
	QByteArray ba = rcc.readAll();
	rcc.close();
	qDebug() << ba << QResource::registerResource(ba.constData());
}
else
{
	qDebug() << "RCC open failed";
}

Result is the content of the RCC file and false.

Christian Ehrlicher

@LazyT said in QResource::registerResource with rccData instead rccFileName:

QResource::registerResource(ba.constData());

registerResource() takes a const uchar *. You're passing a const char * which is not automatically convertible to a const uchar * but instead implicitly converted into a QString because you did not define QT_NO_CAST_FROM_ASCII which you should to avoid such errors.

JonB

@Christian-Ehrlicher Wow!!

LazyT

Hm,

DEFINES += QT_NO_CAST_FROM_ASCII

gives tons of "is private within this context" errors.

QResource::registerResource(reinterpret_cast<const uchar*>(ba.constData()));

results in true, but icons are not available because "qt.svg: Cannot open file 'xxx', because: No such file or directory".

I give up for today.

Thanks for your hints.

Christian Ehrlicher

@LazyT said in QResource::registerResource with rccData instead rccFileName:

gives tons of "is private within this context" errors.

Because you have a lot of implicit casts from char* to QString which are for sure not what you want.

but icons are not available because

Works fine for me:

<RCC>
    <qresource prefix="/">
        <file>stylesheet.qss</file>
        <file>icons/menuIndicatorChecked.png</file>
        <file>icons/menuIndicatorUnchecked.png</file>
        <file>icons/SimulationModeOnNormal.png</file>
        <file>icons/dashedline.png</file>
    </qresource>
</RCC>

int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QFile f("style.rcc");
f.open(QIODevice::ReadOnly);
auto ba = f.readAll();
qDebug() << ba.size();
qDebug() << QResource::registerResource(reinterpret_cast<const uchar*>(ba.constData()));
QFile fRes(":/icons/menuIndicatorChecked.png");
qDebug() << fRes.exists() << fRes.isOpen() << fRes.readAll().size();
return 0;

-->

25888
true
true true 274

LazyT

The problem was

"Warning: The data must remain valid throughout the life of any QFile that may reference the resource data."

Moved the resource from the subroutine and it works now.

Thanks!