blur of 1% is clipped too much

[Alvin Penner]

running Windows XP, Inkscape rev 12342, with a visual bbox as default.
A single Bezier curve was drawn, and the Fill and Stroke dialog was used to assign a blur of 1%. svg file is attached.
The bounds of the blurred object are clipped prematurely, too small.
The premature clipping disappears if the blur is 0.
It also disappears slowly as the blur is increased to about 10% or more.

- not reproduced on Inkscape 0.48.4

[Alvin Penner (apenner)]

attached is a screenshot, just in case.
the screenshot shows that the bbox is a reasonable size, the problem is that the clipping area is noticeably less than the bbox.

[su_v (suv-lp)]

Not reproduced with rev <= 12304 on OS X 10.7.5 (cairo 1.12.14),
reproduced with rev >= 12305

The strong clipping at small % blurs (via Fill&Stroke only) is possibly a side-effect of the fix for bug #1171208 (?).

[Alvin Penner (apenner)]

- I'll look into it some more to see what is going on.

- a somewhat similar effect can be seen using the Filter Editor by itself, in the attached image Blur1Filter.svg. In this case I used the Filter editor on the same image and increased the blur to 4% and saw some evidence of clipping. However in this case the clipping can be removed by going into the Filter Editor and modifying the General Settings.

[Alvin Penner (apenner)]

- fix committed to rev 12362
- the clipping was related to the use of a geometric bbox, rather than visual, when calculating the filter area
- this change will affect all filters, both those that come from the Fill & Stroke blur and also those from the Filter Editor

- I believe this coincidentally fixes Bug 168943, although I am not very familiar with the history of that bug report.

[su_v (suv-lp)]

Follow-up report:
- Bug #1229971 “trunk: incorrect objectBoundingBox for FER (rev >= 12362)”
  <https://bugs.launchpad.net/inkscape/+bug/1229971>