This Month in Linebender, November 2025

content/blog/2025-12-15-tmil-23/index.md

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+title = "Linebender in November 2025"
+authors = ["Kaur Kuut", "Robert Brewitz Borg"]
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+
+Linebender is an informal open-source organization working on various projects to advance the state of the art in GUI for [the Rust programming language](https://rust-lang.org).
+
+## Vello
+
+Vello is our GPU vector renderer.
+It can draw large 2D scenes with high performance, using GPU compute shaders for most of the work.
+
+- [vello#1203][]: Introduced a new clipping algorithm for non-layer based clipping.
+- [vello#1286][]: Added image filters to Vello CPU.
+- [vello#1301][]: Optimized gradient rendering in Vello CPU.
+- [vello#1237][]: Added support for non-isolated masks.
+- [vello#1309][]: Added comprehensive examples to Vello CPU.
+
+<figure>
+<img style="height: auto;" width="1820" height="1818" src="image_filters.png" alt="A grid of nine colorful shapes with various blur and shadow effects applied.">
+<figcaption>
+Vello CPU now has Gaussian Blur, Drop Shadow, and Flood effects.
+</figcaption>
+</figure>
+
+## Masonry and Xilem
+
+Masonry is the widget system developed by Linebender.
+It provides a non-opinionated retained widget tree, designed as a base layer for high-level GUI frameworks.
+
+Xilem is our flagship GUI project, inspired by SwiftUI, which uses Masonry for its widgets.
+It lets you build user interfaces declaratively by composing lightweight views together, and will diff them to provide minimal updates to a retained layer.
+
+- [xilem#1443][]: Added text size config to `Checkbox` and `TextInput`.
+- [xilem#1444][]: Added support for non-contiguous app state.
+- [xilem#1448][]: Changed default background and text colors.
+- [xilem#1461][]: Refactored `xilem_core` module structure.
+- [xilem#1455][]: Reworked `to_do_mvc` example.
+- [xilem#1471][]: Lifted common `View` wrappers to `xilem_core`.
+- [xilem#1470][]: Renamed `MessageContext` to `MessageCtx`.
+- [xilem#1440][]: Added `ResizeObserver` for detecting widget size changes.
+- [xilem#1482][]: Added `Passthrough` widget for simple widget encapsulation.
+- [xilem#1493][], [xilem#1494][]: Added support for efficient child replacement in all widgets.
+- [xilem#1497][], [xilem#1502][]: Standardized widget child management methods.
+- [xilem#1492][]: Added `FocusedBorderColor` property.
+- [xilem#1505][]: Now accepting `state` in `Task` view.
+- [xilem#1499][]: Split off `WindowView` code into `MasonryRoot`.
+- [xilem#1490][]: Upgraded to Parley v0.7.0.
+
+Eli Heuer has made significant progress in porting our old Druid hero app, [Runebender][], to Xilem.\
+Check out the [port's repo][] or follow the progress on [Zulip][Xilem Runebender Zulip].
+
+<figure>
+<img style="height: auto;" width="1920" height="1326" src="runebender_xilem.png" alt="A screenshot of the Runebender font editor showing the letter a being edited.">
+<figcaption>
+Runebender is being ported to Xilem.
+</figcaption>
+</figure>
+
+## Parley
+
+Parley is a text layout library.
+It handles text layout, mostly at the level of line breaking and resolving glyph positions.
+
+We released [Parley 0.7][]. 🎉
+
+- [parley#449][]: Optimized line height computation.
+- [parley#367][]: Added `TextWrapMode` style.
+- [parley#452][]: Introduced Unicode data in preparation of migrating to ICU4X.
+- [parley#468][]: Added word and letter spacing to text layout based on style properties.
+- [parley#467][], [parley#471][]: Added `fontconfig-dlopen` feature to Fontique to control how to load the fontconfig library.
+- [parley#276][]: Improved trailing whitespace handling.
+
+We have also won not just [one][NLnet-1] but [two][NLnet-2] grants from [NLnet][] for additional work on Parley in 2026.
+More updates to follow as we finalize the plans.
+
+<img style="width: 25%;" src="nlnet_banner.svg" alt="NLnet foundation logo." />
+
+## Kurbo
+
+Kurbo provides data structures and algorithms for curves and vector paths.
+
+We released [Kurbo 0.13][]. 🎉
+
+- [kurbo#493][]: Converted `CubicBez::nearest` to the `poly-cool` quintic solver for a nice speedup (3000x for high accuracy!) and better robustness. This just missed the 0.13 release train.
+- [kurbo#521][], [kurbo#522][], [kurbo#525][], [kurbo#524][], [kurbo#526][]: Marked a bunch of methods `const`.
+- [kurbo#527][]: Derived `Hash` for `Axis`.
+
+## Fearless SIMD
+
+Fearless SIMD is our SIMD infrastructure library.
+It provides a solid way for writing SIMD operations portably across WASM, Aarch64, x86, and x86_64.
+
+- [fearless_simd#115][]: Updated x86 codegen to use AVX2 intrinsics.
+- [fearless_simd#123][]: Widened AVX2's associated types to 256 bits.
+- [fearless_simd#120][]: Implemented the reinterpret operations without `bytemuck`.
+- [fearless_simd#130][]: Implemented `core::ops::Not` for integer types.
+- [fearless_simd#134][]: All float-to-integer and integer-to-float conversions are implemented properly on x86. They should now handle all values correctly, including `NaN`.
+- [fearless_simd#136][]: The floating-point `min_precise` and `max_precise` operations now behave the same way on x86 and WebAssembly as they do on AArch64, returning the non-`NaN` operand if one operand is `NaN` and the other is not.
+  Previously, they returned the second operand if either was `NaN`.
+- [fearless_simd#140][]: The `load_interleaved` and `store_interleaved` operations now use native intrinsics on x86, instead of using the fallback implementations.
+- [fearless_simd#143][]: Now using WebAssembly's relaxed SIMD intrinsics if available.
+- [fearless_simd#145][]: Added the `ceil` and `round_ties_even` operations to floating-point vector types.
+
+## Velato
+
+Velato is our Lottie render library.
+The goal is to provide coverage of the large Lottie spec, up to what Vello can render, for use in interactive graphics.
+
+An assortment of fixes and improvements to Velato's Lottie support to render more complex animations correctly, see the linked PRs for details.
+
+- [velato#78][]: Restructured schema to reflect the specification types.
+- [velato#79][]: Now allowing any skew value.
+- [velato#80][]: Replaced `keyframe` with `kurbo` for tweening.
+- [velato#81][]: Now tweening with a cubic bezier curve.
+- [velato#82][]: Fixed flickering issues for certain Lottie configurations.
+- [velato#83][]: Added support for trimmed paths.
+- [velato#84][]: Fixed matte layers.
+- [velato#85][]: Fixed easing handles, by only use the first two components.
+
+## Bevy Vello
+
+Bevy Vello is our Bevy integration for Vello.
+The goal is to provide support for rendering scenes, text, SVGs, and Lotties in the Bevy game engine.
+
+A lot of work was done to update Bevy Vello for Bevy 0.17.
+
+- [bevy_vello#180][]: Updated to Bevy 0.17, plus other dependency updates.
+- [bevy_vello#182][]: Fixed resize render targets on camera viewport change.
+
+## Get Involved
+
+We welcome collaboration on any of our crates.
+This can include improving the documentation, implementing new features, improving our test coverage, or using them within your own code.
+
+We host an hour long office hours meeting each week where we discuss what's going on in our projects.
+See [#office hours in Zulip](https://xi.zulipchat.com/#narrow/channel/359642-office-hours) for details.
+We're also running a separate office hours time dedicated to the renderer collaboration, details also available at that link.
+Note that office hours are on a break for the remainder of the year.
+They are expected to continue in January, keep an eye on Zulip for details.
+
+If you wish to discuss the Linebender project individually, Daniel is offering ["office hours" appointments](https://calendar.google.com/calendar/u/0/appointments/schedules/AcZssZ32eQYJ9DtZ_wJaYNtT36YioETiloZDIdImFpBFRo5-XsqGzpikgkg47LPsiHhpiwiQ1orOwwW2), which are free to book.
+It really helps us to learn what aspects our users care about the most.
+
+[vello#1203]: https://github.com/linebender/vello/pull/1203
+[vello#1286]: https://github.com/linebender/vello/pull/1286
+[vello#1301]: https://github.com/linebender/vello/pull/1301
+[vello#1237]: https://github.com/linebender/vello/pull/1237
+[vello#1309]: https://github.com/linebender/vello/pull/1309
+
+[xilem#1443]: https://github.com/linebender/xilem/pull/1443
+[xilem#1444]: https://github.com/linebender/xilem/pull/1444
+[xilem#1448]: https://github.com/linebender/xilem/pull/1448
+[xilem#1461]: https://github.com/linebender/xilem/pull/1461
+[xilem#1455]: https://github.com/linebender/xilem/pull/1455
+[xilem#1471]: https://github.com/linebender/xilem/pull/1471
+[xilem#1470]: https://github.com/linebender/xilem/pull/1470
+[xilem#1440]: https://github.com/linebender/xilem/pull/1440
+[xilem#1482]: https://github.com/linebender/xilem/pull/1482
+[xilem#1493]: https://github.com/linebender/xilem/pull/1493
+[xilem#1494]: https://github.com/linebender/xilem/pull/1494
+[xilem#1497]: https://github.com/linebender/xilem/pull/1497
+[xilem#1502]: https://github.com/linebender/xilem/pull/1502
+[xilem#1492]: https://github.com/linebender/xilem/pull/1492
+[xilem#1505]: https://github.com/linebender/xilem/pull/1505
+[xilem#1499]: https://github.com/linebender/xilem/pull/1499
+[xilem#1490]: https://github.com/linebender/xilem/pull/1490
+[Runebender]: https://github.com/linebender/runebender
+[port's repo]: https://github.com/eliheuer/runebender-xilem
+[Xilem Runebender Zulip]: https://xi.zulipchat.com/#narrow/channel/197829-runebender/topic/Runebender.20Xilem/with/560954771
+
+[Parley 0.7]: https://github.com/linebender/parley/releases/tag/v0.7.0
+[parley#449]: https://github.com/linebender/parley/pull/449
+[parley#367]: https://github.com/linebender/parley/pull/367
+[parley#452]: https://github.com/linebender/parley/pull/452
+[parley#468]: https://github.com/linebender/parley/pull/468
+[parley#467]: https://github.com/linebender/parley/pull/467
+[parley#471]: https://github.com/linebender/parley/pull/471
+[parley#276]: https://github.com/linebender/parley/pull/276
+[NLnet-1]: https://nlnet.nl/project/Parley/
+[NLnet-2]: https://nlnet.nl/project/Parley-copypaste/
+[NLnet]: https://nlnet.nl/
+
+[Kurbo 0.13]: https://github.com/linebender/kurbo/releases/tag/v0.13.0
+[kurbo#493]: https://github.com/linebender/kurbo/pull/493
+[kurbo#521]: https://github.com/linebender/kurbo/pull/521
+[kurbo#522]: https://github.com/linebender/kurbo/pull/522
+[kurbo#525]: https://github.com/linebender/kurbo/pull/525
+[kurbo#524]: https://github.com/linebender/kurbo/pull/524
+[kurbo#526]: https://github.com/linebender/kurbo/pull/526
+[kurbo#527]: https://github.com/linebender/kurbo/pull/527
+
+[fearless_simd#115]: https://github.com/linebender/fearless_simd/pull/115
+[fearless_simd#123]: https://github.com/linebender/fearless_simd/pull/123
+[fearless_simd#120]: https://github.com/linebender/fearless_simd/pull/120
+[fearless_simd#130]: https://github.com/linebender/fearless_simd/pull/130
+[fearless_simd#134]: https://github.com/linebender/fearless_simd/pull/134
+[fearless_simd#136]: https://github.com/linebender/fearless_simd/pull/136
+[fearless_simd#140]: https://github.com/linebender/fearless_simd/pull/140
+[fearless_simd#143]: https://github.com/linebender/fearless_simd/pull/143
+[fearless_simd#145]: https://github.com/linebender/fearless_simd/pull/145
+
+[velato#78]: https://github.com/linebender/velato/pull/78
+[velato#79]: https://github.com/linebender/velato/pull/79
+[velato#80]: https://github.com/linebender/velato/pull/80
+[velato#81]: https://github.com/linebender/velato/pull/81
+[velato#82]: https://github.com/linebender/velato/pull/82
+[velato#83]: https://github.com/linebender/velato/pull/83
+[velato#84]: https://github.com/linebender/velato/pull/84
+[velato#85]: https://github.com/linebender/velato/pull/85
+
+[bevy_vello#180]: https://github.com/linebender/bevy_vello/pull/180
+[bevy_vello#182]: https://github.com/linebender/bevy_vello/pull/182