Scribus Forums

Scribus => Beginner Talk => Topic started by: James Glover on August 17, 2017, 04:51:13 am

Title: 360 Deg or 0.00?
Post by: James Glover on August 17, 2017, 04:51:13 am
When rotating a frame or image, what's the difference between 360 deg and 0.00?

0.00 is the default, but 360 doesn't seem to change anything. Just curious.

Title: Re: 360 Deg or 0.00?
Post by: a.l.e on August 17, 2017, 09:38:37 am
i'm curious here: which difference would you expect?
Title: Re: 360 Deg or 0.00?
Post by: James Glover on August 22, 2017, 09:22:12 am
My expectation is that there would be a functional difference between two settings that appear, at first glance, to be quantitatively identical.


Upon close inspection, when a frame or image is rotated to 360 degrees, the thickness of the frame becomes doubled. The frame will retain this double thickness appearance for every other incremental degree of rotation - except 0.0.

My guess is that the double thickness appearance is an indicator that a frame's rotation is something other than default, or 0.0.

How close am I?
Title: Re: 360 Deg or 0.00?
Post by: a.l.e on August 22, 2017, 09:52:25 am
which version of scribus are you using?
Title: Re: 360 Deg or 0.00?
Post by: GarryP on August 22, 2017, 11:25:54 am
This question seemed to be a curious one so I did some quick tests on 1.4.6 on Windows.

First I added a rectangle and set its line width to 3pt. Then I duplicated the rectangle - so I could more clearly see any difference between before and after - and set its rotation - via the PP - to 360deg.

No change in the width of the outline occurred but I did notice a very slight change in the red selection box surrounding the rectangle. The selection box seems to get bigger by one pixel in both X and Y at the top-left of the selection box, as much as I can tell visually (the bottom-right seems to be unaffected). Setting the rotation back to 0 doesn't change the outline width but - in a similar but opposite way to the reverse - the selection box seems to shrink by one pixel at the top-left.

Performing the same rotation on a text frame and an image frame - after giving them an outline colour - produced the same results, I.e. no change in outline width but a very slight, almost imperceptible, change in the selection box position/size. Similar tests on other shapes produced the same expected results.

I cannot replicate James' position regarding "thickness of the frame becomes doubled". I'm not saying that it cannot happen, I just cannot replicate the circumstances. James, if you can show us a video it might help.

Then I looked at rotating the object through the 360deg mark which shows an anomaly. Create any object - frame or shape - and use the PP Rotation up-arrow to rotate the object to, say, 2 deg. Then use the down-arrow to rotate it back to, say, 358deg. What happens is that the rotation value will go: 2, 1, 0, 360, 359, 358. The same thing happens when using the mouse scroll-wheel over the Rotation field.

This gets even worse when you set the rotation to, for example, 2 deg and use CTRL+mouse-wheel to change the rotation by 10 degree increments/decrements. The first down-scroll takes you to 0deg, the next to 360deg, the next to 350deg. The first down-scroll should take you to 352deg but it takes three down-scrolls to get anywhere near and it's still not right.

This behaviour is wrong. As James says, 0deg and 360deg are - in the context of Scribus - the same thing. An object should not be able to have a rotation of 0deg or 360deg. A rotation of 360deg should produce the object's identity, which is where it was at 0deg.

NOTE: For maths/physics geeks, I'm aware that there are situations where an object has to be rotated by 720deg to take it back to its identity but those situations don't exist in the context of a two-dimensional Scribus document.