[GIS] How to snap and move circles by the center

Question

I have a point layer, and a polygon layer with buffers of a given radius around each point. I need to move points, and check that each buffer is not above forbidden land/plots.

In autocad, you can move a circle snapping its center, so you can see immediately the circle limits, and make sure it is not above forbidden land.

Here in qgis, I can only :

1. move my point
2. buffer my point
3. check the buffer doesn't come over forbidden plots.

and if it does, do the process all over again. A pain !

So I would like to :

1. move at the same time point and buffer by the centre, although it is probably impossible as it's on two different layers,

2. move a circle by its center, so I can directly snap it to my point and check the circle position.

Any ideas ?

I guess, it could be a plugin doing polygon centroid + move item snapping by its centroid. I didn't find anything of the kind.

Answer 1

QGIS 2.14 +

Geometry generator has made "dynamic geometries" possible.

On your point layer's Layer Properties window:

1. Click on green plus button.
2. Set Symbol layer type to Geometry generator
3. Select Polygon / Multipolygon as the Geometry type
4. Create an Expression such as buffer($geometry, 2000) (depend on your radius)

Generated buffer(s) will follow the points as you move them.