зеркало из https://github.com/mozilla/gecko-dev.git
118 строки
3.5 KiB
C++
118 строки
3.5 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 ||
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* 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(
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const DisplayItemClipChain* aClipChain, const ActiveScrolledRoot* aASR);
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static bool Equal(const DisplayItemClipChain* aClip1,
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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() { mRefCount++; }
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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,
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const ActiveScrolledRoot* aASR,
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const DisplayItemClipChain* aParent,
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DisplayItemClipChain* aNextClipChainToDestroy)
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: mClip(aClip),
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mASR(aASR),
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mParent(aParent),
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mNextClipChainToDestroy(aNextClipChainToDestroy)
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#ifdef DEBUG
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,
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mOnStack(true)
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#endif
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{
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}
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DisplayItemClipChain()
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: mASR(nullptr),
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mNextClipChainToDestroy(nullptr)
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#ifdef DEBUG
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,
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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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DisplayItemClipChain* mNextClipChainToDestroy;
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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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typedef const DisplayItemClipChain* Key;
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std::size_t operator()(const Key& aKey) const {
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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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typedef const DisplayItemClipChain* Key;
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bool operator()(const Key& lhs, const Key& rhs) const {
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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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