QML Canvas: How to use CanvasWindow and CanvasSize properly

[Indrajit]

I have a qml canvas with many elements, and when I zoom in, the elements needs to redrawn, if the canvas size grows too much, the rendering is delayed and quite visible.

I couldnt use the canvassize, canvaswindow properly to render only part of the scene, didnt find any proper examples to use this.

Could some expert please guide me with very minimalistic code.

Also, I see that these properties are marked as not to be used in future, does anyone know what is it that replaces ?

[Indrajit]

Any experts in this area, if you can please guide me to somewhere or with some code would be great.

Thank you in advance