Renderer: thin lines disappear when zoomed out or downscaled (cairo >= 1.12.4)

Bug #1652039 reported by su_v on 2016-12-22
12
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Inkscape
Medium
Unassigned
cairo
New
Undecided
Bryce Harrington

Bug Description

The new About screen for upcoming Inkscape 0.92 exposes a long-standing issue in Inkscape's cairo-based renderer with cairo >= 1.12.4. Thin lines disappear completely when zooming out, or down-scaling such objects (e.g. as group).

Steps to reproduce:
A) with current RC 0.92pre4 build:
1) launch inkscape
2) open 'Help > About Inkscape'
3) shrink the size of the About dialog

B) with any Inkscape build >= 0.91:
1) download about.svg from repo [1]
2) open 'about.svg' in Inkscape
3) zoom out repeatedly

The smaller the overall output of the line-art drawing, the more it may change appearance because thin lines disappear.

Inkscape's cairo-based renderer does not expose the same issue with older versions of cairo <= 1.12.2 (see attached screenshots with a slightly older trunk build).

Reproduced with Inkscape 0.92.x r15275 and cairo 1.14.6, 1.15.5 (git master) on OS X 10.7.5.

=====
Earlier reports likely related to the same changes in cairo 1.12.4:
Bug #1074612 “No display in outline mode” (fixed)
Bug #1174909 “inkscape fails to print thin lines to PDF” (not fixed)

[1] https://bazaar.launchpad.net/~inkscape.dev/inkscape/0.92.x/files/head:/share/screens/

su_v (suv-lp) wrote :
su_v (suv-lp) wrote :
su_v (suv-lp) wrote :
su_v (suv-lp) wrote :
su_v (suv-lp) wrote :
su_v (suv-lp) on 2016-12-22
description: updated
Bryce Harrington (bryce) on 2016-12-23
Changed in inkscape:
assignee: nobody → Bryce Harrington (bryce)
assignee: Bryce Harrington (bryce) → nobody
Changed in cairo:
assignee: nobody → Bryce Harrington (bryce)
su_v (suv-lp) wrote :

This had initially been reported for the new about screen on irc (#inkscape-devel) by Windows packagers using latest pre-release builds of 0.92 (32bit, 64bit). Up-to-date devlibs for Windows both include affected cairo versions (inkscape-devlibs (32bit): cairo 1.14.6; inkscape-devlibs64 (64bit): cairo 1.15.2). Updating bug status accordingly for project 'Inkscape'.

Changed in inkscape:
status: New → Confirmed
jazzynico (jazzynico) on 2017-01-03
Changed in inkscape:
importance: Undecided → Medium
status: Confirmed → Triaged
Bryce Harrington (bryce) wrote :

Suspecting that the fix to https://bugs.launchpad.net/inkscape/+bug/1174909 (in cairo trunk upstream) may have fixed this issue. Would be worth retesting.

Patrick Storz (ede123) wrote :

Unfortunately not, behavior is unchanged when rendering the about screen on canvas.
(tested with same cairo build I used in the other bug, i.e. 132794f6832ea83e2f9a72e11b05080d2cdf80f8)

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