How to paint using a ball shape and get painted coordinates in qml?

Yunus

Hi all,

I want to create a small rounded shape(ball shape) which should be movable. After that I will move it on the screen to be able to paint the areas which it passed. At the end of the process, I need to get the coordinates of painted areas.

How can I achieve this? Is there an example which is helpful for my problem? I am new on Qt so I prefer examples to adviced methods.

ODБOï

@Yunus hi,
you can use qml Canvas

Yunus

@LeLev Yes Canvas is a possible solution but I dont know how to use it in my case :)

ODБOï

@Yunus http://qteveloper.blogspot.com/2013/08/qml-example-detect-mouse-and-draw-on.html
see also
https://doc.qt.io/qt-5/qtwidgets-widgets-scribble-example.html but it is widget

Yunus

@LeLev Thanks for ur reply. This problem can solve my problem's 1st step but I have still a few questions:

When I moved clicked mouse quickly, canvas cant draw quickly and appears some gaps between lines. Is there a way to fix this issue?
fillRect method is good which is explained here. But I couldnt find a method for circle. Is there a method to do this with circle. Maybe normal "lineTo" method is already circle, But I cant put dots using "lineTo".
The most important one: How can I get the coordinates of painted at the end of process?

Yunus

Actually, I fixed my 1st and 2nd problem too, using lineCap by making it "round". My last problem is getting coordinates of painted part.

ODБOï

@Yunus said in How to paint using a ball shape and get painted coordinates in qml?:

My last problem is getting coordinates of painted part.

have an array, then in the onPaint handler add xpos, ypos to that array

Yunus

@LeLev But doesnt it give only the middle pixels of a thick line. Does it also give all the pixels inside a thick line or only the middle pixel of line?

ODБOï

@Yunus yes it will give positions where mouse moved.

you can also iterate over all the pixels of the canvas

Yunus

@LeLev actually I saved the painted image to a directory using "canvas's save method". And I decided to use that image on C++ side by calling it from directory. I dont know this is efficient or not but I think this can solve my problem