gecko-dev/layout/base/RestyleTracker.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * for the specific language governing rights and limitations under the
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 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 2010
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 * Contributor(s):
 *     Boris Zbarsky <bzbarsky@mit.edu> (original author)
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
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#include "RestyleTracker.h"
#include "nsCSSFrameConstructor.h"
#include "nsStyleChangeList.h"

namespace mozilla {
namespace css {

#define RESTYLE_ARRAY_STACKSIZE 128

static PLDHashOperator
CollectRestyles(nsISupports* aElement,
                RestyleTracker::RestyleData& aData,
                void* aRestyleArrayPtr)
{
  RestyleTracker::RestyleEnumerateData** restyleArrayPtr =
    static_cast<RestyleTracker::RestyleEnumerateData**>
               (aRestyleArrayPtr);
  RestyleTracker::RestyleEnumerateData* currentRestyle =
    *restyleArrayPtr;
  currentRestyle->mElement = static_cast<RestyleTracker::Element*>(aElement);
  currentRestyle->mRestyleHint = aData.mRestyleHint;
  currentRestyle->mChangeHint = aData.mChangeHint;

  // Increment to the next slot in the array
  *restyleArrayPtr = currentRestyle + 1;

  return PL_DHASH_NEXT;
}

inline void
RestyleTracker::ProcessOneRestyle(Element* aElement,
                                  nsRestyleHint aRestyleHint,
                                  nsChangeHint aChangeHint)
{
  if (aElement->GetCurrentDoc() != mFrameConstructor->mDocument) {
    // Content node has been removed from our document; nothing else
    // to do here
    return;
  }

  nsIFrame* primaryFrame = aElement->GetPrimaryFrame();
  if (aRestyleHint & eRestyle_Self) {
    mFrameConstructor->RestyleElement(aElement, primaryFrame, aChangeHint);
  } else if (aChangeHint &&
             (primaryFrame ||
              (aChangeHint & nsChangeHint_ReconstructFrame))) {
    // Don't need to recompute style; just apply the hint
    nsStyleChangeList changeList;
    changeList.AppendChange(primaryFrame, aElement, aChangeHint);
    mFrameConstructor->ProcessRestyledFrames(changeList);
  }

  if (aRestyleHint & eRestyle_LaterSiblings) {
    for (nsIContent* sibling = aElement->GetNextSibling();
         sibling;
         sibling = sibling->GetNextSibling()) {
      if (!sibling->IsElement())
        continue;

      mFrameConstructor->RestyleElement(sibling->AsElement(),
                                        sibling->GetPrimaryFrame(),
                                        NS_STYLE_HINT_NONE);
    }
  }
}

void
RestyleTracker::ProcessRestyles()
{
  PRUint32 count = mPendingRestyles.Count();

  // Make sure to not rebuild quote or counter lists while we're
  // processing restyles
  mFrameConstructor->BeginUpdate();

  // loop so that we process any restyle events generated by processing
  while (count) {
    // Use the stack if we can, otherwise fall back on heap-allocation.
    nsAutoTArray<RestyleEnumerateData, RESTYLE_ARRAY_STACKSIZE> restyleArr;
    RestyleEnumerateData* restylesToProcess = restyleArr.AppendElements(count);

    if (!restylesToProcess) {
      return;
    }

    RestyleEnumerateData* lastRestyle = restylesToProcess;
    mPendingRestyles.Enumerate(CollectRestyles, &lastRestyle);

    NS_ASSERTION(lastRestyle - restylesToProcess == PRInt32(count),
                 "Enumeration screwed up somehow");

    // Clear the hashtable so we don't end up trying to process a restyle we're
    // already processing, sending us into an infinite loop.
    mPendingRestyles.Clear();

    for (RestyleEnumerateData* currentRestyle = restylesToProcess;
         currentRestyle != lastRestyle;
         ++currentRestyle) {
      ProcessOneRestyle(currentRestyle->mElement,
                        currentRestyle->mRestyleHint,
                        currentRestyle->mChangeHint);
    }

    count = mPendingRestyles.Count();
  }

  // Set mInStyleRefresh to false now, since the EndUpdate call might
  // add more restyles.
  mFrameConstructor->mInStyleRefresh = PR_FALSE;

  mFrameConstructor->EndUpdate();

#ifdef DEBUG
  mFrameConstructor->mPresShell->VerifyStyleTree();
#endif
}

} // namespace css
} // namespace mozilla