General and Desktop

@agmar said in How to remove qt_static_metacall errors for removed signal: because it always comes back after some time Because this is generated code! Simply do a complete rebuild: delete build folder, run qmake and build.

@JonB Thankyou for your help too! really appreciate efforts!

@agmar Put the open() as the first thing in openSerial() (actually immediately after the setPortName()). Always check the return result of any open()s. Remove the open() from writeAll().

@lukutis222 I wrote in my previous what I suggest you do.

@gsephelec said in QStandardItem pointer loses value after leaving function: I just couldn't get my head around what I was missing. Well, this is a very rare case and will likely slip through for many C++ programmers. Here is one way to think about this: QStandardItem * passes a copy of the pointer to the function. This is why you change only the copy of the pointer to point to a different object. Hence why others have suggested to use a reference or pointer to the pointer you want to modify.

@SeDi said in QQuickImageProvider - unload Images / free memory: Hi, who owns an image provided by QQuickImageProvider? Does it belong to the displaying QML element or to C++/the provider? Does that depend on the use of the QQIP cache? The function signature indicating an object rather than a reference or pointer makes it clear that the provider does not own the image returned to the QML engine. https://doc.qt.io/qt-6/qquickimageprovider.html#requestImage QImage QQuickImageProvider::requestImage(const QString &id, QSize *size, const QSize &requestedSize) How can I make sure that only a small number of pictures is being held in memory? I have not found anything like a "removeImage()" method. https://doc.qt.io/qt-6/qquickimageprovider.html#image-caching Images returned by a QQuickImageProvider are automatically cached, similar to any image loaded by the QML engine. When an image with a "image://" prefix is loaded from cache, requestImage() and requestPixmap() will not be called for the relevant image provider. If an image should always be fetched from the image provider, and should not be cached at all, set the cache property to false for the relevant Image or BorderImage object. So the decision is made by the consumer of the image, rather than the provider or engine. The provider can of course maintain its own private cache. I have thought about using a QQuickImageProvider to provide hundreds of photos from C++ to QML. I only need about 5-15 of them at a time After their use they have to be deleted from memory, because the user may browse through loads of them and I don't want that excessive use of memory. Does implementing the application using the framework-provided image providers result in acceptable memory usage? I would expect roughly similar consumption.

Your approach is good (and working). You can still avoid some hassle by using lambdas instead. Here is what we basically do in our software: QMetaObject::invokeMethod(qApp, [&errorMessage](){ QMessageBox{icon, "DeepSkyStacker", errorMessage}.exec(); }); Please note that your thread will just continue running before the message box might even be shown. Sometimes you might want to wait for a response by the user. For this we need extra synchronization. I've put several use case into a nice little header-only library: https://github.com/SimonSchroeder/QtThreadHelper You can have a look how you might solve some of the problems.

@RahibeMeryem Did you actually read my previous post? Or why do you ask me same question again?

@Christian-Ehrlicher thanks. it had solved.

@adazem009 Some variant of this question surfaces every few months, almost always initiated by someone who really does not understand what the internet is. InterNet in itself is an ambiguous term. It is a network of interconnected networks. There is no internet point of authority to ping with and come to the conclusion "I can reach the internet". It is by nature designed so that some segments may be reached even if other large portions are down. So, you need to be very specific with your intentions and expectations when branching outside of your LAN (local area network).

@kipalex the conflict is notified to you through the warning (ALWAYS FIX THE WARNINGS).

Hi, I think you should be able to achieve this with QCharts. Otherwise, projects worth taking a look at: Qwt QCustomPlot Check their licenses to see if they fit your needs.

@Axel-Spoerl 👏Thanks a lot

@Christian-Ehrlicher It took me a whole day, but I finally understood that you were referring to the fact that exit()/quit() can't be used in the same vein as requestInterruption()/isInterruptionRequested() or terminate(). I first learned about basic QThread semantics so long ago (more than a decade I think), that the fact that it's possible to not understand that got completely lost on me.

Here's a specific example of how QML Layouts appears to be broken. I have a GridLayout with 4 colums and 5 rows. The cells in the 3th column each contain a GroupBox and with "Layout.fillWidth: true" in each GroupBox, the 3rd column expands when the app width is increased. That's what I want. However in the top cell of the 4th column, I want to have text which is right and top aligned within the cell. QML won't let me do it. I've tried various alignments and anchors, tried putting the text in a Rectangle & child GridLayout within the parent cell and with addition Rectangles (inside the child GridLayout) to push the text to the top right corner, and even tried used "Layout.fillWidth: true" in the Rectangle. Nothing works, and "Layout.fillWidth: true" causes the 4th column to expand at the same rate as the 3rd column, which is not what I want. Am I missing something obvious? Thanks, Michael

@mjsmithers A warning for what? This has nothing to do with QThread particularly, any QObject-derived class will have this issue. And Qt (Creator) is not a compiler, your compiler is external, so it could not "provide a warning".