Rendering black bars with specific SVG

[Tim Sheridan]

This is the specific SVG that's causing this issue: https://developer.apple.com/wwdc/images/hero.svg

Screenshot attached showing an example of black bars. The pattern varies depending on zoom level. At outer zoom levels, it the bars do not appear, but some elements of the SVG are not rendered.

I've reproduced it in 0.92.x branch with both macOS and Ubuntu builds. It renders without black bars in 0.91. I've not tested against trunk yet.

[Tim Sheridan (tghs)]

Example of the black bars

[Tim Sheridan (tghs)]

Reference good render from Safari.

[Tim Sheridan (tghs)]

Outer zoom level showing no black bars but some missing elements.

[Alvin Penner (apenner)]

- confirmed on Windows 10, Inkscape 0.92.1 r15371 (32 bit)
- confirmed on Windows 10, Inkscape 0.92+devel 15536

I occasionally also get vertical bars, shown here

[su_v (suv-lp)]

Based on tests with archived builds (on OS X 10.7.5):
- not reproduced with Inkscape 0.91 r13725,
- not reproduced with lp:inkscape rev <= 13638,
- reproduced with lp:inkscape rev >= 13646,
the rendering regression was likely exposed with changes in the experimental branch which was merged into trunk (after lp:inkscape/0.91.x was branched) in rev 13641:

Changelog:
https://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/changes/13646

Revision 13641: Merge experimental
https://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/13641

[su_v (suv-lp)]

Note that the rendering of the test case with Inkscape 0.91 - while not showing black bars - is incorrect too (many filled areas seem to be missing or only partially rendered, and outline view mode shows missing paths (or path segments) compared to 0.92.x).

[su_v (suv-lp)]

A reduced test case of a (random) path which renders with the bounding box rendered as solid black fill in 0.92.x, instead of the brownish fill area defined by the path geometry (as shown in the node tool).

The rendering is restored if any of the nodes is modified with the node tool.

[su_v (suv-lp)]

15 paths identified as triggers for rendering issues (black bars), each wrapped into separate sub-layer.

[Jonathan Hofinger (jhofinger)]

The isolated paths all have an arc with rx or ry=0, so it's the same issue as https://gitlab.com/inkscape/inkscape/-/issues/692. On editing with the node tool, the arcs are replaced by cubic bezier segments which don't have that problem.

Closed by: https://gitlab.com/jhofinger