WebKit Igalia Periodical #15

Implemented support for setting returnValue for <dialog> with Invoker Commands.

After fixing an issue with Trusted Types when doing attribute mutation within the default callback, and implementing performance improvements for Trusted Types enforcement, the Trusted Types implementation is now considered stable and has been enabled by default.

Landed one fix which, along with previous patches, solved the webKitMediaSrcStreamFlush() crash reported in bug #260455.

Unfortunately, in some pages where the crash previously occurred, now a different blank video bug has been revealed. The cause of this bug is known, but fixing it would cause performance regressions in pages with many video elements. Work is ongoing to find a better solution for both.

The initial support of MP4-muxed WebVTT in-band text tracks is about to be merged, which will bring this MSE feature to the ports using GStreamer. Text tracks for the macOS port of WebKit only landed two weeks ago and we expect there will be issues to iron out in WebKit ports, multiplatform code and even potentially in spec work—we are already aware of a few potential ones.

Note that out-of band text-tracks are well supported in MSE across browsers and commonly used. On the other hand, no browsers currently ship with in-band text track support in MSE at this point.

Support for MediaStreamTrack.configurationchange events was added, along with related improvements in the GStreamer PipeWire plugin. This will allow WebRTC applications to seamlessly handle default audio/video capture changes.

Continued improving the support for handling graphics damage:

• Added support for validating damage rectangles in Layout Tests.

• Landed a change that adds layout tests covering the damage propagation feature.

• Landed a change that fixes damage rectangles on layer resize operations.

• Landed a change that improves damage rectangles produced by scrolling so that they are clipped to the parent container.

The number of threads used for painting with the GPU has been slightly tweaked, which brings a measurable performance improvement in all kinds of devices with four or mores processor cores.

The stable branch for the upcoming 2.48.x stable release series of the GTK and WPE ports has been created. The first preview releases from this branch are WebKitGTK 2.47.90 and WPE WebKit 2.47.90. People willing to report issues and help with stabilization are encouraged to test them and report issues in Bugzilla.

Published a blog post that presents an opinionated approach to the work with textual logs obtained from WebKit and GStreamer.