1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7 #ifndef DISPLAYITEMCLIPCHAIN_H_
8 #define DISPLAYITEMCLIPCHAIN_H_
10 #include "mozilla/Assertions.h"
11 #include "DisplayItemClip.h"
14 class nsIScrollableFrame
;
18 struct ActiveScrolledRoot
;
21 * A DisplayItemClipChain is a linked list of DisplayItemClips where each clip
22 * is associated with an active scrolled root that describes what the clip
24 * We use a chain instead of just one intersected clip due to async scrolling:
25 * A clip that moves along with a display item can be fused to the item's
26 * contents when drawing the layer contents, but all other clips in the chain
27 * need to be kept separate so that they can be applied at composition time,
28 * after any async scroll offsets have been applied.
29 * The clip chain is created during display list construction by the builder's
30 * DisplayListClipState.
31 * The clip chain order is determined by the active scrolled root order.
32 * For every DisplayItemClipChain object |clipChain|, the following holds:
33 * !clipChain->mParent ||
34 * ActiveScrolledRoot::IsAncestor(clipChain->mParent->mASR, clipChain->mASR).
35 * The clip chain can skip over active scrolled roots. That just means that
36 * there is no clip that moves with the skipped ASR in this chain.
38 struct DisplayItemClipChain
{
40 * Get the display item clip in this chain that moves with aASR, or nullptr
41 * if no such clip exists. aClipChain can be null.
43 static const DisplayItemClip
* ClipForASR(
44 const DisplayItemClipChain
* aClipChain
, const ActiveScrolledRoot
* aASR
);
46 static bool Equal(const DisplayItemClipChain
* aClip1
,
47 const DisplayItemClipChain
* aClip2
);
49 * Hash function that returns the same value for any two clips A and B
50 * where Equal(A, B) is true.
52 static uint32_t Hash(const DisplayItemClipChain
* aClip
);
54 static nsCString
ToString(const DisplayItemClipChain
* aClipChain
);
56 bool HasRoundedCorners() const;
58 void AddRef() { mRefCount
++; }
60 MOZ_ASSERT(mRefCount
> 0);
64 DisplayItemClipChain(const DisplayItemClip
& aClip
,
65 const ActiveScrolledRoot
* aASR
,
66 const DisplayItemClipChain
* aParent
,
67 DisplayItemClipChain
* aNextClipChainToDestroy
)
71 mNextClipChainToDestroy(aNextClipChainToDestroy
)
72 #if defined(DEBUG) || defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED)
79 DisplayItemClipChain()
81 mNextClipChainToDestroy(nullptr)
82 #if defined(DEBUG) || defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED)
89 DisplayItemClip mClip
;
90 const ActiveScrolledRoot
* mASR
;
91 RefPtr
<const DisplayItemClipChain
> mParent
;
92 uint32_t mRefCount
= 0;
93 DisplayItemClipChain
* mNextClipChainToDestroy
;
94 #if defined(DEBUG) || defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED)
99 struct DisplayItemClipChainHasher
{
100 typedef const DisplayItemClipChain
* Key
;
102 std::size_t operator()(const Key
& aKey
) const {
103 return DisplayItemClipChain::Hash(aKey
);
107 struct DisplayItemClipChainEqualer
{
108 typedef const DisplayItemClipChain
* Key
;
110 bool operator()(const Key
& lhs
, const Key
& rhs
) const {
111 return DisplayItemClipChain::Equal(lhs
, rhs
);
115 } // namespace mozilla
117 #endif /* DISPLAYITEMCLIPCHAIN_H_ */