[Interest] QDatastream, QMap, QImage serialization

[Jason H]

 > * QPaintDevice has the concept of "physical DPI" and "logical DPI" which are GUI-related.

 > * QPainter depends on QPaintEngine which depends on QPaintDevice
 > * QPen depends on QBrush which depends on QPixmap
 > * QPen and QBrush are useless without QPainter
 > * QImage inherits QPaintDevice

What is the logical / physical DPI of a QImage? I'd assume 1:1.

QBrush can return a a texture as:
- QPixmap texture() or 
- QImage textureImage()

which makes me think it should be T texture<T>();

All this non-gui art refactoring definitely has to wait until Qt6, but I think it'd be very welcome by the (surprisingly) many of us using Qt for non-gui stuff. 



Additionally, I was wondering if there is a Qt-based image manipulation library? I've been hacking my own together called FluentImage, which is QImage with a d "fluent" interface. Or may be add it to QImage?

FluentImage blurred = FlutentImage(QImage()).scale(.5).rotate(45).blur();