Rendering quality issues with custom QQuickPaintedItem

[daljit97]

I have a created a small drawing application in QML, I created a small subclass of QQuickPaintedItem. Then in QML, I used a MouseArea to feed the input to my class. From there I simply store the mouse positions in a vector and then paint the points as I receive onto a QImage using QPainter (I used a simple algorithm to draw a quadratic bezier curve using the last three points in my vector). Then I call QQuickPainted::update() and in my implementation of QQuickPaintedItem::paint() I draw the image. Now the program works ok, but the problem is that the rendering of the painting is quite poor (I am already using QPainter::AntiAliasing). Below there is a picture. As you can see the curves are not very sharp and I can see the "pixels" on oblique lines (when I try the same thing with OneNote everything is smooth and nice). Here is the git repo if you want to test it out. Is there something I can do about this?
.