зеркало из https://github.com/mozilla/gecko-dev.git
59 строки
2.2 KiB
C
59 строки
2.2 KiB
C
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/* -*- Mode: C++; tab-width: 20; 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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#ifndef DISPLAYITEMCLIPCHAIN_H_
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#define DISPLAYITEMCLIPCHAIN_H_
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#include "mozilla/Assertions.h"
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#include "DisplayItemClip.h"
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#include "nsString.h"
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class nsIScrollableFrame;
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namespace mozilla {
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struct ActiveScrolledRoot;
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/**
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* A DisplayItemClipChain is a linked list of DisplayItemClips where each clip
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* is associated with an active scrolled root that describes what the clip
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* moves with.
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* We use a chain instead of just one intersected clip due to async scrolling:
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* A clip that moves along with a display item can be fused to the item's
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* contents when drawing the layer contents, but all other clips in the chain
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* need to be kept separate so that they can be applied at composition time,
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* after any async scroll offsets have been applied.
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* The clip chain is created during display list construction by the builder's
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* DisplayListClipState.
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* The clip chain order is determined by the active scrolled root order.
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* For every DisplayItemClipChain object |clipChain|, the following holds:
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* !clipChain->mParent || ActiveScrolledRoot::IsAncestor(clipChain->mParent->mASR, clipChain->mASR).
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* The clip chain can skip over active scrolled roots. That just means that
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* there is no clip that moves with the skipped ASR in this chain.
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*/
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struct DisplayItemClipChain {
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/**
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* Get the display item clip in this chain that moves with aASR, or nullptr
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* if no such clip exists. aClipChain can be null.
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*/
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static const DisplayItemClip* ClipForASR(const DisplayItemClipChain* aClipChain,
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const ActiveScrolledRoot* aASR);
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static bool Equal(const DisplayItemClipChain* aClip1, const DisplayItemClipChain* aClip2);
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static nsCString ToString(const DisplayItemClipChain* aClipChain);
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bool HasRoundedCorners() const;
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DisplayItemClip mClip;
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const ActiveScrolledRoot* mASR;
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const DisplayItemClipChain* mParent;
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};
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} // namespace mozilla
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#endif /* DISPLAYITEMCLIPCHAIN_H_ */
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