General and Desktop

Thank you for the tip!

@Christian-Ehrlicher & @JonB , ty for your answers, it's clear now.

I did not, sorry

Hi the syntax is not correct should be connect(button, SIGNAL(sendDeleteSignal()), this, SLOT(checkForDeletes())); with no classname:: and would show paramters if it has any. Also Did you remember Q_OBJECT class Button : public QPushButton { Q_OBJECT Please show Buttons .h file It must also inherit from a QWidget or QObject which your error suggests you did not. And as @JonB says, the new syntax is far better as it helps to find errors. connect(button, &Button::sendDeleteSignal, this, &MainWindow::checkForDeletes);

Hi and welcome to the forums We are users here and questions about future development plans are better asked at https://lists.qt-project.org/ where the Qt devs hang out. ps PgModeler is awesome :)

@J-Hilk Thanks a lot, the hint index.row(); has worked for me, and now I can display the relevant data on the second screen. Since I am reading data from android storage and I've noticed that QPixmap don't work to display image using a label, but fortunately ui->label->setText("<img src=/storage/emulated/0/Plots/xyz.jpg align=middle width=600 height=600>"); works.

Ok, after long perturbations I used program: https://geekflare.com/create-port-listener-in-windows-or-linux/ and created listening port 5000, then ran Qt project and everything is fine. Thanks for all your patience :) To conclude, passing passoword as I mentioned above is not mandatory.

@Christian-Ehrlicher said in How QSharedPointer works?: The pointer ptr becomes managed by this QSharedPointer and must not be passed to another QSharedPointer object or deleted outside this object. Yeah, now I get it but it wasn't obvious for me then, I was like "but I want to have many QSharedPointers" :(

Maybe that QByteArray is the culprit, you could try rewrite into more vanilla standard: ... { QByteArray block; QBuffer buffer(&block); buffer.open(QIODevice::WriteOnly); QDataStream out(&buffer); ... at least you would expose more stuff to the debugger :-)

Hi, The widget in your QMdiSubwindow is a tabs object, correct ? If so, you should use qobject_cast and then call the method you want on it.

Please show the complete backtrace. I would guess you're trying to delete an object/widget twice.

Hi Just to make sure you understand. When you install Qt from Qt site you get the normal version. However, Unbuntu also allows you to use apt-get an Qt version. ( often Not the newest but close) If you use that version, then you can also apt-get thd MySql stuff that is compiled with the unbuntu version of Qt. So ifs not critical to use the absolute newest Qt then Remove the version from Qt site and apt-get Qt from ubuntu and the MySql Stuff and it should just work with no extra effort.

@yijia Maybe with different QLabel and QPixmap or QPicture https://doc.qt.io/qt-5/qlabel.html#pixmap-prop https://doc.qt.io/qt-5/qlabel.html#setPicture

@sdttn Hi! I had the same issue. And the problem was that Qt couldn't find libdl.so To fix this I put libdl.so in /sysroot/usr/lib. To find it i add -feature-library flag to ./configure. That command what i use: ./configure -release -opengl es2 -device linux-rasp-pi3-g++ -device-option CROSS_COMPILE=armv8-rpi3-linux-gnueabihf- -sysroot /mnt/second/proj/dai/env/work/sysroot -opensource -confirm-license -make libs -nomake examples -nomake tests -prefix /usr/local/qt5pi -extprefix /mnt/second/proj/dai/env/work/qt5pi -hostprefix /mnt/second/proj/dai/env/work/qt5 -v -no-use-gold-linker -sql-mysql -mysql_config /mnt/second/proj/dai/env/work/../mysql_config -ssl -openssl-runtime -feature-library

Hi If you assign the stylesheet to the top widget ( like the dialog) it should replace the old stylesheet if you load another styleSheet and apply to the same to object. However, you might need to ask Dialog to redraw itself via update() if its still not refreshed, you can try style()->unpolish(this); style()->polish(this);

@SGaist Thanks for the response. The example I gave was a reduction of what's happening in my larger application, where use of Pillow is for other reasons as well, not applicable to this example. As far as I'm aware the images are not of a special type. The testcard image, which I downloaded just for the sake of this test, was (if I remember correctly) from here: https://upload.wikimedia.org/wikipedia/en/5/52/Testcard_F.jpg

QGraphicsScene::items or QGraphicsView::items (the overloads taking a QPointF), perhaps?