Webrender: Is there a way to achieve backdrop-filter blur (aka frosted glass effect) using Webrender?

[fasihrana]

I know this has been an outstanding issue for Mozilla Bug 1178765, but is this going to be looked at in Webrender? Alternatively, is there a way to achieve the effect in Webrender by using existing builder/pipeline funtions?

[kvark]

I know a person who would know without investigation. cc @gw3583

[gw3583]

It's not currently supported. I think it's probably not a huge amount of work (although I haven't read the bug in detail) - my guess is we could base it on the mix-blend-mode code which does a readback, and then feed that into a blur task? Either way, it's probably going to be low priority in the short term though.

[fasihrana]

I think the arguments to function push_stacking_context would need to be changed to something as follows:

pub fn push_stacking_context(
        &mut self,
        info: &LayoutPrimitiveInfo,
        clip_node_id: Option<ClipId>,
        transform_style: TransformStyle,
        mix_blend_mode: MixBlendMode,
        back_drop_filters: Vec<FilterOp>,
        filters: Vec<FilterOp>,
        glyph_raster_space: GlyphRasterSpace,
    )

This would allow more filters to be accessible using the "backdrop-filter" css property. I'm not sure how mix_blend_mode argument would be affected though or if it can be removed altogether?

[Darkspirit]

(Alexandre Dieulot from bug 1178765 comment 45)

Chrome is now working on that feature.
https://bugs.chromium.org/p/chromium/issues/detail?id=497522#c134

Three months ago:

While we can't promise when the feature will be added, I wanted to let you know that we did hear your comments. We're going to try to make progress on this feature in the next few months.

Three weeks ago:

We may restart work on this feature soon, please stay tuned. The next step is to fix an error in the specification.

Today it was assigned to someone.

[dralley]

The attached BZ was marked RESOLVED FIXED