Live preview for graphics item in Qt

[anda_skoa]

How to achieve a line having First Click and Second Click as end points only? And how to delete the previous lines which show the preview while the mouse is moved?

I am afraid I don't understand the problem.

It sounds like you are doing something like creating CadCommandAdd instances for every mouse move instead of just when you finish the line.
If that is the case just don't do that.

Cheers,
_

[Kamalpreet]

It sounds like you are doing something like creating CadCommandAdd instances for every mouse move instead of just when you finish the line.
If that is the case just don't do that.

I have created an instance of CadCommandAdd only in mousePressEvent of the graphics scene when mouse is pressed for the first time when it is in graphics scene.
While mouse is moved, only the updated position is obtained. No instances of CadCommandAdd are created while mouseMoveEvent.

[anda_skoa]

In that case my guess would be too aggressive caching.

Cheers,
_