Re:A Single Div
by pcwalton on Thursday July 14, 2016 @04:56PM
(#12097107)
> Edge is usually pretty modern when it comes to GPU acceleration, and I've heard Servo is heading this way, but Apple has historically cared very little about animation performance on WebKit, instead hoping to drive people to write native iOS apps
This isn't really an accurate description of the current state of affairs.
Edge, Firefox, Chrome, and Safari all use essentially the same architecture for rendering. In the case of all browsers but Chrome and Firefox on non-Windows platforms, they are already doing all their rendering using vector graphics APIs that are GPU-assisted (Direct2D for Edge and Firefox; CG::OGL for Safari); at least on Windows, Chrome is the last one to catch up here. All browsers use a "paint"/"compositor" distinction, which leads to the "transform/opacity is fast, other CSS properties are slow" effect. In the case of Safari, the compositor is run by the OS window server (Core Animation); Chrome is heading this way too on Mac. For other browsers and OS's, the compositing is done by the browser itself.
This design, which essentially all shipping browsers share, is motivated not by Web compatibility concerns but rather because it was easy to retrofit onto older browser engines. Servo does things differently: it removes the distinction between painting and compositing, replacing it with WebRender, an integrated solution that handles both. This means that it can run animations off the main thread and GPU-accelerate all of them, not just transform and opacity. The legacy vector graphics APIs are cut out of the picture entirely (except for SVG/canvas), which results in a much more optimized graphics pipeline. We do not break the Web while doing so; there is nothing in the spec that requires the use of legacy vector graphics APIs when painting Web content.
This isn't really an accurate description of the current state of affairs.
Edge, Firefox, Chrome, and Safari all use essentially the same architecture for rendering. In the case of all browsers but Chrome and Firefox on non-Windows platforms, they are already doing all their rendering using vector graphics APIs that are GPU-assisted (Direct2D for Edge and Firefox; CG::OGL for Safari); at least on Windows, Chrome is the last one to catch up here. All browsers use a "paint"/"compositor" distinction, which leads to the "transform/opacity is fast, other CSS properties are slow" effect. In the case of Safari, the compositor is run by the OS window server (Core Animation); Chrome is heading this way too on Mac. For other browsers and OS's, the compositing is done by the browser itself.
This design, which essentially all shipping browsers share, is motivated not by Web compatibility concerns but rather because it was easy to retrofit onto older browser engines. Servo does things differently: it removes the distinction between painting and compositing, replacing it with WebRender, an integrated solution that handles both. This means that it can run animations off the main thread and GPU-accelerate all of them, not just transform and opacity. The legacy vector graphics APIs are cut out of the picture entirely (except for SVG/canvas), which results in a much more optimized graphics pipeline. We do not break the Web while doing so; there is nothing in the spec that requires the use of legacy vector graphics APIs when painting Web content.