On Wed, Mar 24, 2010 at 12:55 PM, bulia byak <buliabyak@...233.....400...> wrote:

On Wed, Mar 24, 2010 at 4:04 AM, Zhenfeng Zhao
<zhenfeng.zhao.8@...400...> wrote:
> Hello,
>
> I am interested in working on the "transformation-anchors" project in GSOC
> this year. I am a graduate student in Computer Science in Canada.

Great, thanks! Please take into account my comment at the page of the spec:

http://wiki.inkscape.org/wiki/index.php/SpecTransformAnchors

As far as I can see the interface mock-ups ignore this comment, so
they need to be redone. The essence of it is that we must not
introduce two different entities: center of rotation and anchor; we
should have a single thing, the one now marked by the cross, and
everything should move it and refer to it. This object already exists
in the code, basically what you need is just add more UI facilities to
move it. It is also (already) automatically saved into SVG per object,
if moved.

OK. I have tried it and found out what it does. The center of rotation, marked as cross, can be dragged and moved to a different location. It is saved for the object, so that when closing and reopening this SVG file, we can see the cross (center of rotation) stays where it is left. In the SVG file, it shows:

inkscape:transform-center-x="7.6874748"
inkscape:transform-center-y="-3.2402241" /

I can see it is a field or attribute of the path object.

So we don't need that star button for separate "rotation
center", but instead we need a way to set its coordinates numerically.

Do you mean that we need some UI facilities to allow moving this center easily with better control? This way, it would be easier for users to know where it can be moved to, and what that will do.

Do we need to use that 9-button-matrix shown in the Wiki?

I understand the needs to input center coordinates. This way, all transformations will perform based on it.

I also tried to move the center, and did some tests for different transformations.
- For rotate and skew, different centers will give different results. (It is the most obvious for rotation.)
- For scale, moving the center gives the same results, with the same transform values.

Are we keep this way?

Regards,

Zhenfeng.

Please feel free to discuss or ask any questions you might have. The
saving of the rotation center was coded by John Cliff, maybe he will
agree to be your mentor for this?

--
bulia byak
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