layout/base/nsStyleChangeList.cpp

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  37
  38 /*
  39  * a list of the recomputation that needs to be done in response to a
  40  * style change
  41  */
  42
  43 #include "nsStyleChangeList.h"
  44 #include "nsStyleConsts.h"
  45 #include "nsIFrame.h"
  46 #include "nsIContent.h"
  47 #include "nsCRT.h"
  48
  49 static const PRUint32 kGrowArrayBy = 10;
  50
  51 nsStyleChangeList::nsStyleChangeList()
  52   : mArray(mBuffer),
  53     mArraySize(kStyleChangeBufferSize),
  54     mCount(0)
  55 {
  56   MOZ_COUNT_CTOR(nsStyleChangeList);
  57 }
  58
  59 nsStyleChangeList::~nsStyleChangeList()
  60 {
  61   MOZ_COUNT_DTOR(nsStyleChangeList);
  62   Clear();
  63 }
  64
  65 nsresult
  66 nsStyleChangeList::ChangeAt(PRInt32 aIndex, nsIFrame*& aFrame, nsIContent*& aContent,
  67                             nsChangeHint& aHint) const
  68 {
  69   if ((0 <= aIndex) && (aIndex < mCount)) {
  70     aFrame = mArray[aIndex].mFrame;
  71     aContent = mArray[aIndex].mContent;
  72     aHint = mArray[aIndex].mHint;
  73     return NS_OK;
  74   }
  75   return NS_ERROR_ILLEGAL_VALUE;
  76 }
  77
  78 nsresult
  79 nsStyleChangeList::ChangeAt(PRInt32 aIndex, const nsStyleChangeData** aChangeData) const
  80 {
  81   if ((0 <= aIndex) && (aIndex < mCount)) {
  82     *aChangeData = &mArray[aIndex];
  83     return NS_OK;
  84   }
  85   return NS_ERROR_ILLEGAL_VALUE;
  86 }
  87
  88 nsresult
  89 nsStyleChangeList::AppendChange(nsIFrame* aFrame, nsIContent* aContent, nsChangeHint aHint)
  90 {
  91   NS_ASSERTION(aFrame || (aHint & nsChangeHint_ReconstructFrame),
  92                "must have frame");
  93   NS_ASSERTION(aContent || !(aHint & nsChangeHint_ReconstructFrame),
  94                "must have content");
  95   NS_ASSERTION(!aContent || aContent->IsNodeOfType(nsINode::eELEMENT),
  96                "Shouldn't be trying to restyle non-elements directly");
  97
  98   if ((0 < mCount) && (aHint & nsChangeHint_ReconstructFrame)) { // filter out all other changes for same content
  99     if (aContent) {
 100       for (PRInt32 index = mCount - 1; index >= 0; --index) {
 101         if (aContent == mArray[index].mContent) { // remove this change
 102           aContent->Release();
 103           mCount--;
 104           if (index < mCount) { // move later changes down
 105             ::memmove(&mArray[index], &mArray[index + 1],
 106                       (mCount - index) * sizeof(nsStyleChangeData));
 107           }
 108         }
 109       }
 110     }
 111   }
 112
 113   PRInt32 last = mCount - 1;
 114   if ((0 < mCount) && aFrame && (aFrame == mArray[last].mFrame)) { // same as last frame
 115     NS_UpdateHint(mArray[last].mHint, aHint);
 116   }
 117   else {
 118     if (mCount == mArraySize) {
 119       PRInt32 newSize = mArraySize + kGrowArrayBy;
 120       nsStyleChangeData* newArray = new nsStyleChangeData[newSize];
 121       if (newArray) {
 122         memcpy(newArray, mArray, mCount * sizeof(nsStyleChangeData));
 123         if (mArray != mBuffer) {
 124           delete [] mArray;
 125         }
 126         mArray = newArray;
 127         mArraySize = newSize;
 128       }
 129       else {
 130         return NS_ERROR_OUT_OF_MEMORY;
 131       }
 132     }
 133     mArray[mCount].mFrame = aFrame;
 134     mArray[mCount].mContent = aContent;
 135     if (aContent) {
 136       aContent->AddRef();
 137     }
 138     mArray[mCount].mHint = aHint;
 139     mCount++;
 140   }
 141   return NS_OK;
 142 }
 143
 144 void
 145 nsStyleChangeList::Clear()
 146 {
 147   for (PRInt32 index = mCount - 1; index >= 0; --index) {
 148     nsIContent* content = mArray[index].mContent;
 149     if (content) {
 150       content->Release();
 151     }
 152   }
 153   if (mArray != mBuffer) {
 154     delete [] mArray;
 155     mArray = mBuffer;
 156     mArraySize = kStyleChangeBufferSize;
 157   }
 158   mCount = 0;
 159 }
 160