Issues when scaling circle objects

Bug #418505 reported by mysparkle on 2009-08-25
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Inkscape
Low
Unassigned

Bug Description

Try this to create the issue:

1. If you create a small circle using the circle tool.
2. Use the start/end nodes to create a very limited arc (very small span between start and end points like 0.5 start and 1.5 end).
3. Scale the arc uniformly by 200% using the ctrl key or the pad look on the transform bar.
4. Try making the circle full by dragging the start/end nodes.
5. Ooops! You will now have an ellips...

The bug is less obvious when you use larger portions of the circle visible. It seems that Inkscape looses track of the actual circle dimensions (diameter/radius) when you limit its visible parts.

Very problematic when trying to use Inkscape for tech stuff.

Thanks,
Lars

su_v (suv-lp) wrote :

Which version of Inkscape did you use for your example? Can you attach a sample drawing?

Can't reproduce this with Inkscape 0.46+devel r22148 on OS X 10.5.8
(settings: geometric bbox, stroke width scaling off, rounded corner radii scaling off, no visible grid, default snapping)

Hi :)

Right now im using:
The latest nightly exe 090810
On:
Windows XP Pro

This bug has been around since 0.46 dist i think.

Ciao,
Lars

-----Ursprungligt meddelande-----
Från: "~suv" <email address hidden>
Till: "lars" <email address hidden>
Skickat: 09-08-25 13:35
Ämne: [Bug 418505] Re: Issues when scaling circle objects

Which version of Inkscape did you use for your example? Can you attach a
sample drawing?

Can't reproduce this with Inkscape 0.46+devel r22148 on OS X 10.5.8
(settings: geometric bbox, stroke width scaling off, rounded corner radii scaling off, no visible grid, default snapping)

--
Issues when scaling circle objects
https://bugs.launchpad.net/bugs/418505
You received this bug notification because you are a direct subscriber
of the bug.

Status in Inkscape: A Vector Drawing Tool: New

Bug description:
Try this to create the issue:

1. If you create a small circle using the circle tool.
2. Use the start/end nodes to create a very limited arc (very small span between start and end points like 0.5 start and 1.5 end).
3. Scale the arc uniformly by 200% using the ctrl key or the pad look on the transform bar.
4. Try making the circle full by dragging the start/end nodes.
5. Ooops! You will now have an ellips...

The bug is less obvious when you use larger portions of the circle visible. It seems that Inkscape looses track of the actual circle dimensions (diameter/radius) when you limit its visible parts.

Very problematic when trying to use Inkscape for tech stuff.

Thanks,
Lars

Hhm, I cannot reproduce this either on Linux. Probably I'm doing something different than you. Could you maybe make a movie to make sure that we're trying to reproduce this using the exact same steps? I know that this is quite some effort, but I don't see an easy other way to nail this bug.

mysparkle (lars-xpressivo) wrote :

Just downloaded a Screencast app :)
Give me a day or two.

Ciao,
Lars
________________________________________
Från: <email address hidden> [<email address hidden>] f&#246;r Diederik van Lierop [<email address hidden>]
Skickat: den 28 augusti 2009 22:52
Till: lars
Ämne: [Bug 418505] Re: Issues when scaling circle objects

Hhm, I cannot reproduce this either on Linux. Probably I'm doing
something different than you. Could you maybe make a movie to make sure
that we're trying to reproduce this using the exact same steps? I know
that this is quite some effort, but I don't see an easy other way to
nail this bug.

--
Issues when scaling circle objects
https://bugs.launchpad.net/bugs/418505
You received this bug notification because you are a direct subscriber
of the bug.

Status in Inkscape: A Vector Drawing Tool: New

Bug description:
Try this to create the issue:

1. If you create a small circle using the circle tool.
2. Use the start/end nodes to create a very limited arc (very small span between start and end points like 0.5 start and 1.5 end).
3. Scale the arc uniformly by 200% using the ctrl key or the pad look on the transform bar.
4. Try making the circle full by dragging the start/end nodes.
5. Ooops! You will now have an ellips...

The bug is less obvious when you use larger portions of the circle visible. It seems that Inkscape looses track of the actual circle dimensions (diameter/radius) when you limit its visible parts.

Very problematic when trying to use Inkscape for tech stuff.

Thanks,
Lars

mysparkle (lars-xpressivo) wrote :

Hi :)

Check this:

http://81.93.138.210/Inkscape/Inkscape_circle_bug.htm

You get the same problem when resizing using the numeric inputs in the panel with the pad lock activated.

Ciao,
Lars
________________________________________
Från: <email address hidden> [<email address hidden>] f&#246;r Diederik van Lierop [<email address hidden>]
Skickat: den 28 augusti 2009 22:52
Till: lars
Ämne: [Bug 418505] Re: Issues when scaling circle objects

Hhm, I cannot reproduce this either on Linux. Probably I'm doing
something different than you. Could you maybe make a movie to make sure
that we're trying to reproduce this using the exact same steps? I know
that this is quite some effort, but I don't see an easy other way to
nail this bug.

--
Issues when scaling circle objects
https://bugs.launchpad.net/bugs/418505
You received this bug notification because you are a direct subscriber
of the bug.

Status in Inkscape: A Vector Drawing Tool: New

Bug description:
Try this to create the issue:

1. If you create a small circle using the circle tool.
2. Use the start/end nodes to create a very limited arc (very small span between start and end points like 0.5 start and 1.5 end).
3. Scale the arc uniformly by 200% using the ctrl key or the pad look on the transform bar.
4. Try making the circle full by dragging the start/end nodes.
5. Ooops! You will now have an ellips...

The bug is less obvious when you use larger portions of the circle visible. It seems that Inkscape looses track of the actual circle dimensions (diameter/radius) when you limit its visible parts.

Very problematic when trying to use Inkscape for tech stuff.

Thanks,
Lars

Pablo Trabajos (pajarico) wrote :

I can confirm this and then some :) I think the key is to make a really small arc, like 0-5 or 0-7 as the reporter noted. There are two variants:
* Unclosed shape: result is the one described in this bug.
* Closed shape: result is a ratio change too, but the other way around (height>width).

I'm attaching a SVG with both examples.

su_v (suv-lp) wrote :

I tried again following the screencast (but it's what I tried before) & comparing my steps with Pablos SVG and could not reproduce the bug with Inkscape 0.46+devel r22179 on OS X 10.5.8 nor with Inkscape 0.46-2. Could this be a platform related bug (if so how?) or some preference settings?

Pablo Trabajos (pajarico) wrote :

Observe how the arc shape looks different from the path in Firefox. It's like it was stretched. What does that mean?

su_v (suv-lp) wrote :

If I open your SVG with Inkscape r22179 and repeat the same steps with the first two arc segments (scale ~ 200% uniformly, then drag start / end nodes) - I get perfect circles in both cases.

But I do see the difference in the rendering of your SVG in Firefox and Batik (compared to Inkscape): the arc seems like squeezed a little bit and its stroke is not uniformly of the same width. Could it be that the transformation matrix isn't correct after the scaling, but only on certain platforms/architectures?

mysparkle (lars-xpressivo) wrote :

Writing this from within my Ubuntu partition and i can "confirm" that this bug does not occur in this version. At least not in the 0.46 dev version i have installed...

________________________________________
Från: <email address hidden> [<email address hidden>] f&#246;r ~suv [<email address hidden>]
Skickat: den 31 augusti 2009 20:04
Till: lars
Ämne: [Bug 418505] Re: Issues when scaling circle objects

I tried again following the screencast (but it's what I tried before) &
comparing my steps with Pablos SVG and could not reproduce the bug with
Inkscape 0.46+devel r22179 on OS X 10.5.8 nor with Inkscape 0.46-2.
Could this be a platform related bug (if so how?) or some preference
settings?

--
Issues when scaling circle objects
https://bugs.launchpad.net/bugs/418505
You received this bug notification because you are a direct subscriber
of the bug.

Status in Inkscape: A Vector Drawing Tool: New

Bug description:
Try this to create the issue:

1. If you create a small circle using the circle tool.
2. Use the start/end nodes to create a very limited arc (very small span between start and end points like 0.5 start and 1.5 end).
3. Scale the arc uniformly by 200% using the ctrl key or the pad look on the transform bar.
4. Try making the circle full by dragging the start/end nodes.
5. Ooops! You will now have an ellips...

The bug is less obvious when you use larger portions of the circle visible. It seems that Inkscape looses track of the actual circle dimensions (diameter/radius) when you limit its visible parts.

Very problematic when trying to use Inkscape for tech stuff.

Thanks,
Lars

su_v (suv-lp) wrote :

@Pablo - are you on Windows XP (I should remember from other comments, but I forgot :)?

confirmed on:
Windows XP Pro

not confirmed on:
Linux (?) (Diederik)
Ubuntu
OS X 10.5.8

Pablo Trabajos (pajarico) wrote :

Yes, XP Pro SP3, inkscape 22040.

su_v (suv-lp) on 2009-08-31
tags: added: transformations win32
jazzynico (jazzynico) wrote :

Confirmed on Vista, Inkscape 0.46, 0.47 and rev9530, with stroke width scaling off. Not reproduced when stroke width scaling is on.

Changed in inkscape:
importance: Undecided → Low
status: New → Confirmed
su_v (suv-lp) wrote :

Comment #8:
> Observe how the arc shape looks different from the path in Firefox.
> It's like it was stretched. What does that mean?

The non-uniformly scaled stroke of the scaled circle/ellipse in other SVG viewers is due to bug #165715 “Stroke to path squashes scaled lines (renderer is wrong)”.

jazzynico (jazzynico) wrote :

Reproduced on Ubuntu 11.04, Inkscape trunk revision 10927.

tags: removed: win32
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