masking with a gradient does not work

[Stefano Facchini]

Masking with a gradient-filled shape does not work. Looking at the xml, it seems that a spurious transformation is applied to the gradient.

Oddly, if I first put the gradient-filled rect in a group on its own, everything works as expected.

[Patrick Storz (ede123)]

Seems to be a regression in master:
- working in Inkscape 0.92.2 (c522dc6d40, 2017-09-16)
- not working in Inkscape 0.92+devel (42c84a5464, 2017-09-20)

[Stefano Facchini (stefano-facchini)]

I think that the most robust way to avoid this problems is to transform the duplicate clipping/masking object directly, instead of: transforming -> duplicating -> transforming back the original.

I attach a proof-of-concept patch of what I mean. Maybe passing along pairs of <node, transformation> is not the best way to do it.

This also solves bug 1719079.

The first patch is just a clean-up (apparently the first argument of doWriteTransform is not really used in the method).

[Stefano Facchini (stefano-facchini)]

Improved version of the patch.

BTW is there a reason why SPClipPath::create is a static method while sp_mask_create is a function?

[Mc (mc...)]

Merged in https://gitlab.com/inkscape/inkscape/commit/f81751abb770d0367d6c515cdcb56a7954714eab