зеркало из https://github.com/mozilla/gecko-dev.git
47 строки
1.9 KiB
C++
47 строки
1.9 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ScrollTypes_h
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#define mozilla_ScrollTypes_h
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// Types used in main-thread scrolling interfaces such as nsIScrollableFrame.
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namespace mozilla {
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/**
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* Scroll modes for main-thread scroll operations. These are mostly used
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* by nsIScrollableFrame methods.
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*
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* When a scroll operation is requested, we ask for instant, smooth,
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* smooth msd, or normal scrolling.
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*
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* |eSmooth| scrolls have a symmetrical acceleration and deceleration curve
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* modeled with a set of splines that guarantee that the destination will be
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* reached over a fixed time interval. |eSmooth| will only be smooth if smooth
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* scrolling is actually enabled. This behavior is utilized by keyboard and
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* mouse wheel scrolling events.
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*
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* |eSmoothMsd| implements a physically based model that approximates the
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* behavior of a mass-spring-damper system. |eSmoothMsd| scrolls have a
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* non-symmetrical acceleration and deceleration curve, can potentially
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* overshoot the destination on intermediate frames, and complete over a
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* variable time interval. |eSmoothMsd| will only be smooth if cssom-view
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* smooth-scrolling is enabled.
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*
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* |eInstant| is always synchronous, |eNormal| can be asynchronous.
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*
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* If an |eInstant| scroll request happens while a |eSmooth| or async scroll is
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* already in progress, the async scroll is interrupted and we instantly
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* scroll to the destination.
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*
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* If an |eInstant| or |eSmooth| scroll request happens while a |eSmoothMsd|
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* scroll is already in progress, the |eSmoothMsd| scroll is interrupted without
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* first scrolling to the destination.
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*/
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enum class ScrollMode { Instant, Smooth, SmoothMsd, Normal };
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} // namespace mozilla
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#endif // mozilla_ScrollTypes_h
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