Scale center

[abercet]

I Andrew.
I don't want to modify center of selected object(4 circle) when I use Scale fonction.
Could you put checkbox in the scale contextual windows
Thank's
QCAD 3.31.2.0/Qt 5.13.2/ MSVC++14.0

[CVH]

Hi,

I replicated your approach by choosing the focus point for scaling on the intersection of the lines.
Then it is utterly correct that the original distance from this intersection to all circle centers is reduced to 80%.
The indicated focus point is the focal point for scaling everything that is selected.

To keep (only) the center of the top right circle steady you need to set the focus point on that center.
Obviously, the middle of all 4 circles will no longer be on the intersection.

I think that you want to scale all circles to 80% in situ, regarding their own center ...
... This can not be accomplished by this tool on all 4 at the same time ... In one action.

Perhaps logical for 4 circles but you could have selected 4 entities without a neat center position.
Splines, Polylines, images, dimensions, Block References, ...


You have two options:
- Scale each circle individually regarding its own center.
- Select all 4 equal sized circles and change their radius/diameter to 80% in one action.

Most input field in QCAD can do calculations.
With the 4 circles selected and a radius of 32 for example, edit the radius field and add times 0.8 > Radius: [32*0.8]

Regards,
CVH

[abercet]

4 circle is for exemple.
That do I do when I select 500 cercles and if I can't use "edit proprity menu"
Best regards

[CVH]

Scaling in situ would work for 500 selected circles of equal size using the Property Editor.

If of a few different sizes you could use the Selection Filter and filter on the circle radius/diameter.
Applying a factor in the Property Editor for each set.
The Selection filter can also make a sub-selection of the 500 selected items with 'Intersect with current selection' based on a property.

Another option is to group your circles based on size in a (temp) layer or with 'Selection groups'.

If all of different size ... 500 different sizes ... Then you have a problem.
One could solve that with a custom script.

Regards,
CVH

[abercet]

Scale for that stars or 100 overse.
We can't select one by one.
Please, we need checkbox option in the scale contextual window.

[CVH]

As already pointed out ...
'Perhaps logical for circles' ... Excluding shapes without a neat center point that can serve as a focal point.

You keep on asking for a checkbox without explaining what 'the checkbox' in question must do for you.
I can add 10 QCheckBox to a QDialog widget but that won't serve anything without knowing what the expectations are.


In the case of your identical irregular stars there are several candidates for a focal point.
One of the corners, the blue marker for example, the center of a bounding box, the geometrical center (Centroid), ...
There are also methods like the Centroid of the hull, center of Largest circle inside a non-convex polygon, ...

For non-identical shapes that is one of the focal point candidates for each.
Not solvable with one single button.


However.
Closely looking at your example we notice that the stars are drawn as 10 line segments each.
That are NOT 3 'star' shapes but rather 30 lines or 30 unrelated drawing entities of the type: Limited line.
You/we see 'stars' ... From QCAD perspective that is nothing more than some arbitrary line-art.
There is no AI behind the scene that recognize the whole as a 5 pointed star

The middle point, the center of the bounding box, the Centroid, ... All coincides for a line segment.
What to use as focal point seems to be very straightforward.
Scaling each line to 80% regarding this point will 'break' the star shapes open at each corner.

The 3 stars can only be regarded as individual closed contours when drawn as 3 Polylines.


Another counter example would be a simple Arc or Ellipse arc shape.
These have a well defined center but that does not coincide with the bounding box center, nor with the middle point.
On top ... They have 2 different Centroid's, one as segment and one as sector.
The list of focal point candidates is about endless.
Again, not solved with a single button.


I am the author of the Centroid's tools.
We could exploit the included resources to scale in regard of the Centroid of any supported shape.
That won't work for your star example as individual lines.
A contour of loose segments is not supported as a shape.
Also, only available for QCAD Pro.

Hereby, I consider this discussion concluded.
Regards,
CVH