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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Declares visibility-related types. @Visibility is an enumeration of the
* possible visibility states of a frame. @OnNonvisible is an enumeration that
* allows callers to request a specific action when a frame transitions from
* visible to nonvisible.
*/
#ifndef mozilla_layout_generic_Visibility_h
#define mozilla_layout_generic_Visibility_h
namespace mozilla {
// Visibility states for frames.
enum class Visibility : uint8_t
{
// Indicates that we're not tracking visibility for this frame.
UNTRACKED,
// Indicates that the frame is probably nonvisible. Visible frames *may* be
// APPROXIMATELY_NONVISIBLE because approximate visibility is not updated
// synchronously. Some truly nonvisible frames may be marked
// APPROXIMATELY_VISIBLE instead if our heuristics lead us to think they may
// be visible soon.
APPROXIMATELY_NONVISIBLE,
// Indicates that the frame is either visible now or is likely to be visible
// soon according to our heuristics. As with APPROXIMATELY_NONVISIBLE, it's
// important to note that approximately visibility is not updated
// synchronously, so this information may be out of date.
APPROXIMATELY_VISIBLE
};
// Requested actions when frames transition to the nonvisible state.
enum class OnNonvisible : uint8_t
{
DISCARD_IMAGES // Discard images associated with the frame.
};
} // namespace mozilla
#endif // mozilla_layout_generic_Visibility_h
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