gecko-dev/layout/base/nsLayoutUtils.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: NPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Netscape 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/NPL/
*
* 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
* Boris Zbarsky <bzbarsky@mit.edu>.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either 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
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* the provisions above, a recipient may use your version of this file under
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*
* ***** END LICENSE BLOCK ***** */
#ifndef nsLayoutUtils_h__
#define nsLayoutUtils_h__
class nsIFrame;
class nsIPresContext;
class nsIContent;
class nsIAtom;
#include "prtypes.h"
#include "nsStyleContext.h"
#include "nsAutoPtr.h"
/**
* nsLayoutUtils is a namespace class used for various helper
* functions that are useful in multiple places in layout. The goal
* is not to define multiple copies of the same static helper.
*/
class nsLayoutUtils
{
public:
/**
* GetBeforeFrame returns the :before frame of the given frame, if
* one exists. This is typically O(1). The frame passed in must be
* the first-in-flow.
*
* @param aFrame the frame whose :before is wanted
* @param aPresContext the prescontext
* @return the :before frame or nsnull if there isn't one
*/
static nsIFrame* GetBeforeFrame(nsIFrame* aFrame, nsIPresContext* aPresContext);
/**
* GetAfterFrame returns the :after frame of the given frame, if one
* exists. This will walk the in-flow chain to the last-in-flow if
* needed. This function is typically O(N) in the number of child
* frames, following in-flows, etc.
*
* @param aFrame the frame whose :after is wanted
* @param aPresContext the prescontext
* @return the :after frame or nsnull if there isn't one
*/
static nsIFrame* GetAfterFrame(nsIFrame* aFrame, nsIPresContext* aPresContext);
/**
* Given a frame, search up the frame tree until we find an
* ancestor "Page" frame, if any.
*
* @param the frame to start at
* @return a frame of type nsLayoutAtoms::pageFrame or nsnull if no
* such ancestor exists
*/
static nsIFrame* GetPageFrame(nsIFrame* aFrame);
/**
* IsGeneratedContentFor returns PR_TRUE if aFrame is generated
* content of type aPseudoElement for aContent
*
* @param aContent the content node we're looking at. If this is
* null, then we just assume that aFrame has the right content
* pointer.
* @param aFrame the frame we're looking at
* @param aPseudoElement the pseudo type we're interested in
* @return whether aFrame is the generated aPseudoElement frame for aContent
*/
static PRBool IsGeneratedContentFor(nsIContent* aContent, nsIFrame* aFrame,
nsIAtom* aPseudoElement);
/**
* HasPseudoStyle returns PR_TRUE if aContent (whose primary style
* context is aStyleContext) has the aPseudoElement pseudo-style
* attached to it; returns PR_FALSE otherwise.
*
* @param aContent the content node we're looking at
* @param aStyleContext aContent's style context
* @param aPseudoElement the name of the pseudo style we care about
* @param aPresContext the presentation context
* @return whether aContent has aPseudoElement style attached to it
*/
static PRBool HasPseudoStyle(nsIContent* aContent,
nsStyleContext* aStyleContext,
nsIAtom* aPseudoElement,
nsIPresContext* aPresContext)
{
NS_PRECONDITION(aPresContext, "Must have a prescontext");
NS_PRECONDITION(aPseudoElement, "Must have a pseudo name");
nsRefPtr<nsStyleContext> pseudoContext;
if (aContent) {
pseudoContext = aPresContext->ProbePseudoStyleContextFor(aContent,
aPseudoElement,
aStyleContext);
}
return pseudoContext != nsnull;
}
};
#endif // nsLayoutUtils_h__