gecko/layout/style/nsStyleContext.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* David Hyatt <hyatt@netscape.com>
* Pierre Phaneuf <pp@ludusdesign.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/* the interface (to internal code) for retrieving computed style data */
#ifndef _nsStyleContext_h_
#define _nsStyleContext_h_
#include "nsRuleNode.h"
#include "nsIAtom.h"
class nsPresContext;
/**
* An nsStyleContext represents the computed style data for an element.
* The computed style data are stored in a set of structs (see
* nsStyleStruct.h) that are cached either on the style context or in
* the rule tree (see nsRuleNode.h for a description of this caching and
* how the cached structs are shared).
*
* Since the data in |nsIStyleRule|s and |nsRuleNode|s are immutable
* (with a few exceptions, like system color changes), the data in an
* nsStyleContext are also immutable (with the additional exception of
* GetUniqueStyleData). When style data change,
* nsFrameManager::ReResolveStyleContext creates a new style context.
*
* Style contexts are reference counted. References are generally held
* by:
* 1. the |nsIFrame|s that are using the style context and
* 2. any *child* style contexts (this might be the reverse of
* expectation, but it makes sense in this case)
* Style contexts participate in the mark phase of rule node garbage
* collection.
*/
class nsStyleContext
{
public:
nsStyleContext(nsStyleContext* aParent, nsIAtom* aPseudoTag,
nsRuleNode* aRuleNode, nsPresContext* aPresContext) NS_HIDDEN;
~nsStyleContext() NS_HIDDEN;
NS_HIDDEN_(void*) operator new(size_t sz, nsPresContext* aPresContext) CPP_THROW_NEW;
NS_HIDDEN_(void) Destroy();
nsrefcnt AddRef() {
if (mRefCnt == PR_UINT32_MAX) {
NS_WARNING("refcount overflow, leaking object");
return mRefCnt;
}
++mRefCnt;
NS_LOG_ADDREF(this, mRefCnt, "nsStyleContext", sizeof(nsStyleContext));
return mRefCnt;
}
nsrefcnt Release() {
if (mRefCnt == PR_UINT32_MAX) {
NS_WARNING("refcount overflow, leaking object");
return mRefCnt;
}
--mRefCnt;
NS_LOG_RELEASE(this, mRefCnt, "nsStyleContext");
if (mRefCnt == 0) {
Destroy();
return 0;
}
return mRefCnt;
}
nsPresContext* PresContext() const { return mRuleNode->GetPresContext(); }
nsStyleContext* GetParent() const { return mParent; }
nsIAtom* GetPseudoType() const { return mPseudoTag; }
NS_HIDDEN_(already_AddRefed<nsStyleContext>)
FindChildWithRules(const nsIAtom* aPseudoTag, nsRuleNode* aRules);
// Does this style context or any of its ancestors have text
// decorations?
PRBool HasTextDecorations() const
{ return !!(mBits & NS_STYLE_HAS_TEXT_DECORATIONS); }
// Does this style context represent the style for a pseudo-element or
// inherit data from such a style context? Whether this returns true
// is equivalent to whether it or any of its ancestors returns
// non-null for GetPseudoType.
PRBool HasPseudoElementData() const
{ return !!(mBits & NS_STYLE_HAS_PSEUDO_ELEMENT_DATA); }
NS_HIDDEN_(void) SetStyle(nsStyleStructID aSID, void* aStruct);
nsRuleNode* GetRuleNode() { return mRuleNode; }
void AddStyleBit(const PRUint32& aBit) { mBits |= aBit; }
/*
* Mark this style context's rule node (and its ancestors) to prevent
* it from being garbage collected.
*/
NS_HIDDEN_(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 functions below are preferred to the use of this
* function.
*/
NS_HIDDEN_(const void*) NS_FASTCALL GetStyleData(nsStyleStructID aSID);
/**
* Define typesafe getter functions for each style struct by
* preprocessing the list of style structs. These functions are the
* preferred way to get style data. The macro creates functions like:
* const nsStyleBorder* GetStyleBorder();
* const nsStyleColor* GetStyleColor();
*/
#define STYLE_STRUCT(name_, checkdata_cb_, ctor_args_) \
NS_HIDDEN_(const nsStyle##name_ *) NS_FASTCALL GetStyle##name_();
#include "nsStyleStructList.h"
#undef STYLE_STRUCT
NS_HIDDEN_(const void*) PeekStyleData(nsStyleStructID aSID);
NS_HIDDEN_(void*) GetUniqueStyleData(const nsStyleStructID& aSID);
NS_HIDDEN_(nsChangeHint) CalcStyleDifference(nsStyleContext* aOther);
#ifdef DEBUG
NS_HIDDEN_(void) List(FILE* out, PRInt32 aIndent);
#endif
protected:
NS_HIDDEN_(void) AddChild(nsStyleContext* aChild);
NS_HIDDEN_(void) RemoveChild(nsStyleContext* aChild);
NS_HIDDEN_(void) ApplyStyleFixups(nsPresContext* aPresContext);
nsStyleContext* const mParent;
// Children are kept in two circularly-linked lists. The list anchor
// is not part of the list (null for empty), and we point to the first
// child.
// mEmptyChild for children whose rule node is the root rule node, and
// mChild for other children. The order of children is not
// meaningful.
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;
// The rule node is the node in the lexicographic tree of rule nodes
// (the "rule tree") that indicates which style rules are used to
// compute the style data, and in what cascading order. The least
// specific rule matched is the one whose rule node is a child of the
// root of the rule tree, and the most specific rule matched is the
// |mRule| member of |mRuleNode|.
nsRuleNode* const 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;
};
NS_HIDDEN_(already_AddRefed<nsStyleContext>)
NS_NewStyleContext(nsStyleContext* aParentContext,
nsIAtom* aPseudoTag,
nsRuleNode* aRuleNode,
nsPresContext* aPresContext);
#endif