Switch to using animation request for scroll inertia dispatch#18997
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You can test this PR using the following package version. |
| return true; | ||
| }, TimeSpan.FromMilliseconds(16), DispatcherPriority.Background); | ||
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| MediaContext.Instance.RequestAnimationFrame(StartInertia); |
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You can use TopLevel.RequestAnimationFrame method, as it's a stable API. MediaContext is internal.
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Note that animation frames will be toplevel-scoped at some point too, the plan is to not trigger callbacks if toplevel isn't visible or is being throttled by the system compositor.
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Unfortunately, TopLevel is in the Controls project, and not the Base project.
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| var speed = _inertia * Math.Pow(InertialResistance, (_lastTime - _inertiaStartTime).TotalSeconds); | ||
| var distance = speed * elapsedSinceLastTick.TotalSeconds; | ||
| _inertiaDispatchOperation = Dispatcher.UIThread.InvokeAsync(() => |
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Can you add a comment here, that we actually want InvokeAsync only to raise events with Input priority?
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IIRC from the discussion, priority change was the only reason.
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| }, TimeSpan.FromMilliseconds(16), DispatcherPriority.Background); | ||
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| MediaContext.Instance.RequestAnimationFrame(StartInertia); |
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I think StartInertial should be called directly from PointerReleased. There is no reason to delay that.
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| var elapsedSinceLastTick = timeSpan - _lastTime; |
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All of those calculations should live in Input priority callback. The only job of animation frame callbacks is to throttle inertia events. OnAnimationRequested should just post a callback via dispatcher.
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You can test this PR using the following package version. |
…iaUI#18997) * switch to using animation request for scroll inertia dispatch * run inertia calcs in dispatcher operation
…iaUI#18997) * switch to using animation request for scroll inertia dispatch * run inertia calcs in dispatcher operation
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What does the pull request do?
This PR dispatches scroll inertia events on animation tick. This provides much smoother inertia scrolling on high framerate devices.
What is the current behavior?
Scroll inertia was dispatched on 16ms interval, limiting it to 60fps. Devices with higher framerate or variable framerate will have choppy scroll animations when inertia is started.
What is the updated/expected behavior with this PR?
How was the solution implemented (if it's not obvious)?
Checklist
Breaking changes
Obsoletions / Deprecations
Fixed issues