gecko-dev/layout/style/nsStyleContext.h

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 *   David Hyatt <hyatt@netscape.com>
 *   Pierre Phaneuf <pp@ludusdesign.com>
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#ifndef _nsStyleContext_h_
#define _nsStyleContext_h_

#include "nsRuleNode.h"

class nsIPresContext;
class nsIAtom;

class nsStyleContext
{
public:
  nsStyleContext(nsStyleContext* aParent, nsIAtom* aPseudoTag, 
                 nsRuleNode* aRuleNode, nsIPresContext* aPresContext);
  ~nsStyleContext();

  void* operator new(size_t sz, nsIPresContext* aPresContext) CPP_THROW_NEW;
  void Destroy();

  nsrefcnt AddRef() {
    ++mRefCnt;
    NS_LOG_ADDREF(this, mRefCnt, "nsStyleContext", sizeof(nsStyleContext));
    return mRefCnt;
  }

  nsrefcnt Release() {
    --mRefCnt;
    NS_LOG_RELEASE(this, mRefCnt, "nsStyleContext");
    if (mRefCnt == 0) {
      Destroy();
      return 0;
    }
    return mRefCnt;
  }

  nsStyleContext* GetParent() const { return mParent; }

  nsStyleContext* GetFirstChild() const { return mChild; }

  already_AddRefed<nsIAtom> GetPseudoType() const;

  already_AddRefed<nsStyleContext> 
  FindChildWithRules(const nsIAtom* aPseudoTag, nsRuleNode* aRules);

  PRBool    Equals(const nsStyleContext* aOther) const;
  PRBool    HasTextDecorations() { return mBits & NS_STYLE_HAS_TEXT_DECORATIONS; };

  void GetBorderPaddingFor(nsStyleBorderPadding& aBorderPadding);

  void SetStyle(nsStyleStructID aSID, nsStyleStruct* aStruct);

  void GetRuleNode(nsRuleNode** aResult) { *aResult = mRuleNode; }
  void AddStyleBit(const PRUint32& aBit) { mBits |= aBit; }
  void GetStyleBits(PRUint32* aBits) { *aBits = mBits; }

  /*
   * Mark this style context's rule node (and its ancestors) to prevent
   * it from being garbage collected.
   */
  void Mark();

  /*
   * Get the style data for a style struct.  This is the most important
   * member function of nsIStyleContext.  It fills in a const pointer
   * to a style data struct that is appropriate for the style context's
   * frame.  This struct may be shared with other contexts (either in
   * the rule tree or the style context tree), so it should not be
   * modified.
   *
   * This function will NOT return null (even when out of memory) when
   * given a valid style struct ID, so the result does not need to be
   * null-checked.
   *
   * The typesafe global helper function |GetStyleData| (below) is
   * preferred to the use of this function (and is a simple typesafe
   * wrapper for this function).
   *
   * See also |nsIFrame::GetStyleData| and the other global
   * |GetStyleData| in nsIFrame.h.
   */
  const nsStyleStruct* GetStyleData(nsStyleStructID aSID);

  const nsStyleStruct* PeekStyleData(nsStyleStructID aSID);

  nsStyleStruct* GetUniqueStyleData(nsIPresContext* aPresContext, const nsStyleStructID& aSID);

  void ClearStyleData(nsIPresContext* aPresContext, nsIStyleRule* aRule);

  nsChangeHint CalcStyleDifference(nsStyleContext* aOther);

#ifdef DEBUG
  void DumpRegressionData(nsIPresContext* aPresContext, FILE* out, PRInt32 aIndent);

  void List(FILE* out, PRInt32 aIndent);
#endif

protected:
  // A default ctor is needed to use nsRefPtr (nsDerivedSafe) with this class.
  // It should never be called.
  nsStyleContext() { NS_NOTREACHED("nsStyleContext default ctor"); }

  void AppendChild(nsStyleContext* aChild);
  void RemoveChild(nsStyleContext* aChild);

  void ApplyStyleFixups(nsIPresContext* aPresContext);

  nsStyleContext* mParent;
  nsStyleContext* mChild;
  nsStyleContext* mEmptyChild;
  nsStyleContext* mPrevSibling;
  nsStyleContext* mNextSibling;

  // If this style context is for a pseudo-element, the pseudo-element
  // atom.  Otherwise, null.
  nsCOMPtr<nsIAtom> mPseudoTag;

  nsRuleNode*             mRuleNode;

  // |mCachedStyleData| points to both structs that are owned by this
  // style context and structs that are owned by one of this style
  // context's ancestors (which are indirectly owned since this style
  // context owns a reference to its parent).  If the bit in |mBits| is
  // set for a struct, that means that the pointer for that struct is
  // owned by an ancestor rather than by this style context.
  nsCachedStyleData       mCachedStyleData; // Our cached style data.
  PRUint32                mBits; // Which structs are inherited from the
                                 // parent context.
  PRUint32                mRefCnt;
};

already_AddRefed<nsStyleContext>
NS_NewStyleContext(nsStyleContext* aParentContext,
                   nsIAtom* aPseudoTag,
                   nsRuleNode* aRuleNode,
                   nsIPresContext* aPresContext);


// typesafe way to access style data.  See nsStyleStruct.h and also
// overloaded function in nsIFrame.h.
template <class T>
inline void
GetStyleData(nsStyleContext* aStyleContext, const T** aStyleStruct)
{
    *aStyleStruct = NS_STATIC_CAST(const T*,
                         aStyleContext->GetStyleData(NS_GET_STYLESTRUCTID(T)));
}

#endif