зеркало из https://github.com/mozilla/gecko-dev.git
117 строки
3.3 KiB
C++
117 строки
3.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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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/**
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* Hash function that returns the same value for any two clips A and B
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* where Equal(A, B) is true.
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*/
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static uint32_t Hash(const DisplayItemClipChain* aClip);
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static nsCString ToString(const DisplayItemClipChain* aClipChain);
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bool HasRoundedCorners() const;
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void AddRef() {
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mRefCount++;
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}
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void Release() {
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MOZ_ASSERT(mRefCount > 0);
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mRefCount--;
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}
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DisplayItemClipChain(const DisplayItemClip& aClip, const ActiveScrolledRoot* aASR, const DisplayItemClipChain* aParent)
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: mClip(aClip)
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, mASR(aASR)
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, mParent(aParent)
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#ifdef DEBUG
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, mOnStack(true)
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#endif
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{}
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DisplayItemClipChain()
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: mASR
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{
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nullptr
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}
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#ifdef DEBUG
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, mOnStack(true)
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#endif
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{
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}
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DisplayItemClip mClip;
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const ActiveScrolledRoot* mASR;
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RefPtr<const DisplayItemClipChain> mParent;
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uint32_t mRefCount = 0;
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#ifdef DEBUG
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bool mOnStack;
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#endif
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};
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struct DisplayItemClipChainHasher
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{
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typedef const DisplayItemClipChain* Key;
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std::size_t operator()(const Key& aKey) const
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{
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return DisplayItemClipChain::Hash(aKey);
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}
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};
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struct DisplayItemClipChainEqualer
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{
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typedef const DisplayItemClipChain* Key;
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bool operator()(const Key& lhs, const Key& rhs) const
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{
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return DisplayItemClipChain::Equal(lhs, rhs);
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}
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};
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} // namespace mozilla
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#endif /* DISPLAYITEMCLIPCHAIN_H_ */
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