possible bug -roll IM 6.8.7.2 Q16 Mac OSX

[fmw42]

It would appear that -roll is not working when the +x coordinate is +0.

This does not work
convert -size 200x100 xc:black xc:white -append -roll +0+50 show:

This works fine
convert -size 200x100 xc:black xc:white -append -roll +1+50 show:

It has been this way at least as far back as IM 6.8.6.9 (which is as far back as I can test these days) and also broke in the current IM 6.8.7.3 beta.


Note also the documentation seems to have the direction of roll backwards. Positive (not negative) values should be left to right or top to bottom. I can change this documentation if desired.


-roll {+-}x{+-}y

roll an image vertically or horizontally by the amount given.
A negative x offset rolls the image left-to-right. A negative y offset rolls the image top-to-bottom.

[magick]

We can reproduce the problem you posted and have a patch in ImageMagick 6.8.7-3 Beta available by sometime tomorrow. Thanks.