tor-browser

The Tor Browser
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DisplayItemClipChain.cpp (3097B)

      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/. */
      6 
      7 #include "DisplayItemClipChain.h"
      8 
      9 #include "nsDisplayList.h"
     10 
     11 namespace mozilla {
     12 
     13 /* static */ const DisplayItemClip* DisplayItemClipChain::ClipForASR(
     14    const DisplayItemClipChain* aClipChain, const ActiveScrolledRoot* aASR) {
     15  while (aClipChain &&
     16         !ActiveScrolledRoot::IsAncestor(aClipChain->mASR, aASR)) {
     17    aClipChain = aClipChain->mParent;
     18  }
     19  return (aClipChain && aClipChain->mASR == aASR) ? &aClipChain->mClip
     20                                                  : nullptr;
     21 }
     22 
     23 bool DisplayItemClipChain::Equal(const DisplayItemClipChain* aClip1,
     24                                 const DisplayItemClipChain* aClip2) {
     25  if (aClip1 == aClip2) {
     26    return true;
     27  }
     28 
     29  if (!aClip1 || !aClip2) {
     30    return false;
     31  }
     32 
     33  bool ret = aClip1->mASR == aClip2->mASR && aClip1->mClip == aClip2->mClip &&
     34             Equal(aClip1->mParent, aClip2->mParent);
     35  // Sanity check: if two clip chains are equal they must hash to the same
     36  // thing too, or Bad Things (TM) will happen.
     37  MOZ_ASSERT(!ret || (Hash(aClip1) == Hash(aClip2)));
     38  return ret;
     39 }
     40 
     41 uint32_t DisplayItemClipChain::Hash(const DisplayItemClipChain* aClip) {
     42  if (!aClip) {
     43    return 0;
     44  }
     45 
     46  // We include the number of rounded rects in the hash but not their contents.
     47  // This is to keep the hash fast, because most clips will not have rounded
     48  // rects and including them will slow down the hash in the common case. Note
     49  // that the ::Equal check still checks the rounded rect contents, so in case
     50  // of hash collisions the clip chains can still be distinguished using that.
     51  uint32_t hash = HashGeneric(aClip->mASR, aClip->mClip.GetRoundedRectCount());
     52  if (aClip->mClip.HasClip()) {
     53    const nsRect& rect = aClip->mClip.GetClipRect();
     54    // empty rects are considered equal in DisplayItemClipChain::Equal, even
     55    // though they may have different x and y coordinates. So make sure they
     56    // hash to the same thing in those cases too.
     57    if (!rect.IsEmpty()) {
     58      hash = AddToHash(hash, rect.x, rect.y, rect.width, rect.height);
     59    }
     60  }
     61 
     62  return hash;
     63 }
     64 
     65 /* static */
     66 nsCString DisplayItemClipChain::ToString(
     67    const DisplayItemClipChain* aClipChain) {
     68  nsAutoCString str;
     69  for (auto* sc = aClipChain; sc; sc = sc->mParent) {
     70    if (sc->mASR) {
     71      str.AppendPrintf("0x%p <%s> %s", sc, sc->mClip.ToString().get(),
     72                       ActiveScrolledRoot::ToString(sc->mASR).get());
     73    } else {
     74      str.AppendPrintf("0x%p <%s> [root asr]", sc, sc->mClip.ToString().get());
     75    }
     76    if (sc->mParent) {
     77      str.AppendLiteral(", ");
     78    }
     79  }
     80  return std::move(str);
     81 }
     82 
     83 bool DisplayItemClipChain::HasRoundedCorners() const {
     84  return mClip.GetRoundedRectCount() > 0 ||
     85         (mParent && mParent->HasRoundedCorners());
     86 }
     87 
     88 }  // namespace mozilla