47 lines
1.7 KiB
C++
47 lines
1.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* 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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/**
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* Declares visibility-related types. @Visibility is an enumeration of the
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* possible visibility states of a frame. @OnNonvisible is an enumeration that
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* allows callers to request a specific action when a frame transitions from
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* visible to nonvisible.
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*/
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#ifndef mozilla_layout_generic_Visibility_h
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#define mozilla_layout_generic_Visibility_h
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namespace mozilla {
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// Visibility states for frames.
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enum class Visibility : uint8_t
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{
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// Indicates that we're not tracking visibility for this frame.
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UNTRACKED,
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// Indicates that the frame is probably nonvisible. Visible frames *may* be
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// APPROXIMATELY_NONVISIBLE because approximate visibility is not updated
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// synchronously. Some truly nonvisible frames may be marked
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// APPROXIMATELY_VISIBLE instead if our heuristics lead us to think they may
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// be visible soon.
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APPROXIMATELY_NONVISIBLE,
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// Indicates that the frame is either visible now or is likely to be visible
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// soon according to our heuristics. As with APPROXIMATELY_NONVISIBLE, it's
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// important to note that approximately visibility is not updated
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// synchronously, so this information may be out of date.
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APPROXIMATELY_VISIBLE
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};
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// Requested actions when frames transition to the nonvisible state.
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enum class OnNonvisible : uint8_t
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{
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DISCARD_IMAGES // Discard images associated with the frame.
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};
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} // namespace mozilla
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#endif // mozilla_layout_generic_Visibility_h
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