qtbase | Qt Base

A GIF picture cannot have more than 256 unique colours. When you load such an image into Qt, it is internally represented in that exact format with the palette (of 256 colours) from the GIF representation, even if your hardware might be able to display many more colours.

This also means that when you scale such an image, Qt is not allowed to extend the colour space to render in-between colours - This means that scaled GIF pictures generally have to look much worse than scaled high-colour images.

The solution to this is either to transform the QImage you created from a GIF picture into a format with a larger colour space before scaling it (with QImage::convertToFormat) or, better still, don't use GIF images at all. After all, GIF is a format developed 30 years ago and has never really been updated to adapt to modern hardware, and using it, you artificially limit your programs to the capabilities of that format.

Let's fix this.

I've managed to run wkhtmltopdf isolated on a docker container.

Dockerfile:

The model provided by the example only accepts setting data with role Qt::EditRole. See line 263 in treemodel.cpp

You are confusing the index of the data points in the vector m_series and their x value. When the data point with x = old_x_min goes out of the window you want to display, then that data point is at index 0 not at index old_x_min.

Replace

Thanks to lixinwei (https://bugreports.qt.io/browse/QTBUG-89993) the issue is resolved. Now, it successfully finds the OpenSSL and MySQL libs.

Cmake paramaters:

The problem is in the last return of data(), which should not return 0.

When returning 0, the view or its delegate(s) try to convert the value in a suitable type for that role, and since one of the first roles requested by a view is the size hint (and cannot convert your returned "0" to a valid size hint), the result is that it will not request any other data: since the size is invalid, the item is considered hidden, thus there's no need to ask for other roles.

Just remove the return 0 at the end of data(), as the implicit return is enough.

PS: the self.emit syntax you're using is considered obsolete, change that to self.numberPopulated.emit(itemsToFetch); also, explicit overloads are not required for signals that only have a single signature, so you can remove the ["QString"] from textChanged and [int] from numberPopulated.
I also suggest you to always leave at least a blank line between functions, as it makes your code much more readable.

Can RegOpenKeyEx/RegCreateKeyEx return NULL as a valid HKEY value?

No, a valid opened HKEY is never NULL.

On the other hand, the value of the returned HKEY is indeterminate if these functions fail. The Win32 API documentation does not say one way or the other if the HKEY gets set to NULL on failure, so you can't rely solely on checking the returned HKEY for NULL vs non-NULL when calling these functions, eg:

Finally, I was successful. I found the Phoronix article about Qt6.

Qt6 started to use the conan.io package manager. So the sources provided by the Qt installer are sufficient. It downloads sources of the qtimageformats to the following location ~/Qt/AdditionalLibraries/Qt/qtimageformats-6.0.0.

Conan will do the rest.

After I did everything I described in the edit I solved it. Basically I went to QtCreator, added a new library to the project (C:\Program Files\MySQL\MySQL Connector C 6.1\libmysql.lib) and now everything works properly!