1252603 - Assertion failure: !aExtraMasksTransform.HasNonTranslation()

Status: RESOLVED DUPLICATE of bug 1229095

(Core :: SVG, defect)

Description

[Bob Clary [:bc] (inactive)]

Attachment: minidump crash report windows nightly

1. http://www.nasaspaceflight.com/2016/02/industry-forward-exploration-hardware/
2. Assertion failure: !aExtraMasksTransform.HasNonTranslation(), at c:/builds/moz2_slave/m-cen-w64-d-000000000000000000/build/src/layout/svg/nsSVGClipPathFrame.cpp:221

Beta/45, Aurora/46, Nightly/47 Windows and Linux at least. OSX not tested.

Reproducible with saved version of the page.

Comment 1

[Carsten Book [:Tomcat]]

Attachment: windows debug build stack with todays m-c tip

Comment 2

[Carsten Book [:Tomcat]]

mats, Ting-Yu is this something for you ?

Comment 3

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Sorry, I don't know SVG. Jonathan?

Comment 4

[Mats Palmgren (inactive)]

Sorry, I'm not familiar with this code.

Comment 6

[Carsten Book [:Tomcat]]

daniel, jonathan: can you take a look at this ?

Comment 7

[Jonathan Watt [:jwatt]]

We hit this code when we have both a mask and a clip-path on an element, which maybe explains why this isn't a common issue.

The assert was originally added to the code in:

  https://hg.mozilla.org/mozilla-central/rev/5515fd47eb5a

where it was !aInputMaskTransform.HasNonTranslation() (different argument name). Shame the assertion didn't add a string to explain what the issue is. :) However, the issue is that the DrawTarget::MaskSurface call that follows can only mask with an offset - a point which it gets from aInputMaskTransform - so if aInputMaskTransform contains anything other than a translation we are going to mask with the mask in the wrong position. In other words the result of failing this assertion should (just) be some mis-rendering.

The value for aExtraMaskTransform can come from either of:

https://mxr.mozilla.org/mozilla-central/source/layout/svg/nsSVGIntegrationUtils.cpp?rev=5dfa8eff77b6&mark=592-594#592

https://mxr.mozilla.org/mozilla-central/source/layout/svg/nsSVGMaskFrame.cpp?rev=e8c7dfe727cd&mark=259-260#259

In both case the Matrix includes the gfxContext's current transform, so we will fail this assertion if there is a non-translation in the transform to the root element (roughly speaking).

I don't have time to fix this properly right now, but I'd be happy to change the assert to something less aggressive than MOZ_ASSERT.