Canvas drawing errors in 0.92.x after r15024

[David Evans]

As a byproduct of 0.92.x r15024 (reverted previous changes to canvas drawing widget) canvas drawing errors have been introduced in the 0.92.x branch. Rows about 16px high are offset horizontally from their correct position on a periodic basis. This appears to occur about every 100px vertically.

Attached is a screenshot showing the effect on the initial empty document window.

Reverting to 0.92.x r15023 restores correct drawing behavior.

[su_v (suv-lp)]

As mentioned earlier in reply to tweenk's request for tests in bug #1571192: reproduced on OS X 10.7.5 with GTK+/X11 2.24.29 and GTK+/Quartz 2.24.30.

This regression was introduced in lp:inkscape/0.92.x r15024 which reverted (parts of) the canvas refactoring from the hackfest 2016.

[jazzynico (jazzynico)]

Reproduced on Windows XP, Inkscape 0.92.x rev. 15025.
Not reproduced with trunk rev. 15028.

[su_v (suv-lp)]

Based on archived GTK2 trunk builds [1] before and during the hackfest:
- not reproduced with rev <= 14783
- rendering issue reproduced with rev 14790, 14792, 14793
- not reproduced with rev >= 14795 [2]

[1] autotools-based builds on OS X 10.7.5, using GTK+/X11 2.24.29
[2] Rendering issues (with GTK2) exposed (as well as fixed) later on during the hackfest differed from the one tracked in this report for current lp:inkscape/0.92.x.

[jazzynico (jazzynico)]

Seems to be fixed with the patch attached in bug #1608216 "Crash when resizing the application window", comment #8.
Please test!

[su_v (suv-lp)]

Patch [1] tested successfully with lp:inkscape/0.92.x r15024, r15043, GTK+/X11 2.24.29 (on OS X 10.7.5): the patched builds no longer expose canvas rendering artifacts as tracked by this report.

Not tested for unintended side-effects possibly exposed elsewhere.
--
[1] https://bugs.launchpad.net/inkscape/+bug/1608216/+attachment/4723363/+files/1608216-CrashResizing.diff

[Jabiertxof (jabiertxof)]

Patch[1] tested in lp:inkscape/0.92.x on Debian Strech r.15043
[1] https://bugs.launchpad.net/inkscape/+bug/1608216/+attachment/4723363/+files/1608216-CrashResizing.diff

[Jabiertxof (jabiertxof)]

tested saccesfuly

[jazzynico (jazzynico)]

Tested successfully on Xubuntu 16.04 and committed rev. 15044.