transforming object with filter applied causes it to render blurry

[insaner]

on r13850,

applying filters to transformed objects causes them to render blurry. Workaround is to place the rotated object into a new group and apply the filter to the group.

to reproduce the problem:

create a simple object, a star works great.
give it your favorite color, and set stroke to black so you get a visible (but not too thick) outline
create a copy (Ctrl + D) and a clone (Alt + D)
apply the following simple filter (create it using the filter editor) to the original object:
      morphology (source graphic) with Erode radius 10, add a composite effect (source alpha, morphology) with "over" as your operator.
this should create an inset in a darker color

now rotate your clone and notice it go blurry.
undo the rotation
rotate your original and notice both go blurry.
rotate your copy (that does not have the filter applied) and apply the filter. notice it is blurry.
unapply the filter, and place the copy into its own group (ctrl + G).
apply the filter to the group and notice that it doesnt go blurry.

[insaner (insaner)]

perhaps related:
 bug #169071 rendering regression on filtered transformed objects
 bug #188814 bad render of some filter effects on transformed objects

[su_v (suv-lp)]

AFAICT the 'blurriness' is specific to the new renderer in trunk. With the old renderer in current stable Inkscape 0.48.x (default prefs), the rotated filtered object renders noticeably pixelated (bug #1058960, bug #806028).

[Ubuntu Newbie (ultragamer)]

If you create a group (ctrl g) and then apply the filter it doesn't become blurry.

But

If you rotate that group at all and apply the filter it becomes blurry.

[su_v (suv-lp)]

Updating bug status based on report linked as duplicate.

[jazzynico (jazzynico)]

Reproduced on Xubuntu 16.04, Inkscape 0.92.x rev. 15055.

[Łukasz Rumin (lukasr93)]

Confirmed on Inkscape 0.92.4, KDE Neon 5.16 User Edition based on Ubuntu 18.04. Workaround works.