Proposal: New, decoupled SVG rendering

[lukemcdo]

Proposal: Introduce a new, decoupled SVG rendering system to replace the UWP option

Summary

UWP SVG rendering is relatively slow and lacks substantial features compared to many modern SVG renderers, so a change would be appreciated.

The first goal of this would simply be to no longer guarantee that SVGs render the same in dot releases, to allow for future work in replacing SVG rendering.

Rationale

• A new library for SVG rendering in WinUI could bring SVGs in WinUI/UWP apps to near-performance parity with PNGs, which brings a variety of upsides to applications that want to support HDPI displays without large file sizes.
• A new library could improve the cross-platform nature of rendering SVGs. This could improve consistency for Xamarin/MAUI/Uno.
• Decoupling this also continues the philosophical trend of WinUI 3: allow for out-of-band work to improve the ecosystem, and engage the community.

Scope

Capability	Priority
This proposal will allow developers to use a performant, modern SVG renderer	Must
This proposal will allow developers to choose their own SVG rendering library	Could
This proposal will allow developers to choose the old UWP SVG rendering library	Could
This proposal will allow end users to use any DPI screen (SVG rerendering with multimonitor)	Should

Worth noting -- I don't have a candidate library in mind. I just know that there are a lot of people itching for SVG in more places in WinUI, UWP, and throughout the Windows GUI, and the groundwork of decoupling the SVG rendering seems important toward this goal.

[michael-hawker]

🦙 I believe Win2D itself has better support for SVG, there's a wrapper based on Win2D here and a Skia based one here with it's own SourceGenerator version here too.

I think it'd probably be best to just build on top of one of these solutions and if anything provide better hooks for dynamic XAML/Binding/Themes/Animation using them instead.

[jevansaks]

🦙 I believe Win2D itself has better support for SVG,

I don't think so, Win2D just delegates the work to D2D which is what XAML uses too. See the link at the bottom of that doc to https://docs.microsoft.com/en-us/windows/win32/direct2d/svg-support?redirectedfrom=MSDN

[lukemcdo]

Even if it doesn't, I'm hopeful for some sort of notice in the WinUI 3 RTM release commenting that SVG output may not be identical. As I understand it, otherwise changing it could be considered a breaking change which couldn't go in a 3.X release.

[EmilysDad]

Please don't throw the baby out with the bath water.

SVG in more places and better rendering in WinUI 3 is an excellent proposal, so long as interfaces remain standardized.

Unfortunately, too often, personal syntax and grammar preferences seem to change elements wholesale with no improvement in the engineering. Interfaces do not need to be "beautiful" or "elegant" or be "a joy to program" please.

[lukemcdo]

Why would you assume that the interfaces would change when the entire request is to change the underlying implementation? This issue is in no danger of reaching that scope and your comment doesn't feel like it belongs in a GitHub thread of this scope.