gecko-dev/layout/base/nsLayoutUtils.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is Netscape
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* Copyright (C) 1998 Netscape Communications Corporation. All
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*
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#include "nsLayoutUtils.h"
#include "nsIFrame.h"
#include "nsIPresContext.h"
#include "nsIContent.h"
#include "nsFrameList.h"
#include "nsLayoutAtoms.h"
#include "nsIAtom.h"
#include "nsCSSPseudoElements.h"
/**
* A namespace class for static layout utilities.
*/
/**
* GetFirstChildFrame returns the first "real" child frame of a
* given frame. It will descend down into pseudo-frames (unless the
* pseudo-frame is the :before generated frame).
* @param aPresContext the prescontext
* @param aFrame the frame
* @param aFrame the frame's content node
*/
static nsIFrame*
GetFirstChildFrame(nsIPresContext* aPresContext,
nsIFrame* aFrame,
nsIContent* aContent)
{
NS_PRECONDITION(aFrame, "NULL frame pointer");
nsIFrame* childFrame;
// Get the first child frame
aFrame->FirstChild(aPresContext, nsnull, &childFrame);
// If the child frame is a pseudo-frame, then return its first child.
// Note that the frame we create for the generated content is also a
// pseudo-frame and so don't drill down in that case
if (childFrame &&
childFrame->IsPseudoFrame(aContent) &&
!childFrame->IsGeneratedContentFrame()) {
return GetFirstChildFrame(aPresContext, childFrame, aContent);
}
return childFrame;
}
/**
* GetLastChildFrame returns the last "real" child frame of a
* given frame. It will descend down into pseudo-frames (unless the
* pseudo-frame is the :after generated frame).
* @param aPresContext the prescontext
* @param aFrame the frame
* @param aFrame the frame's content node
*/
static nsIFrame*
GetLastChildFrame(nsIPresContext* aPresContext,
nsIFrame* aFrame,
nsIContent* aContent)
{
NS_PRECONDITION(aFrame, "NULL frame pointer");
// Get the last in flow frame
nsIFrame* lastInFlow = aFrame->GetLastInFlow();
// Get the last child frame
nsIFrame* firstChildFrame;
lastInFlow->FirstChild(aPresContext, nsnull, &firstChildFrame);
if (firstChildFrame) {
nsFrameList frameList(firstChildFrame);
nsIFrame* lastChildFrame = frameList.LastChild();
NS_ASSERTION(lastChildFrame, "unexpected error");
// Get the frame's first-in-flow. This matters in case the frame has
// been continuted across multiple lines
lastChildFrame = lastChildFrame->GetFirstInFlow();
// If the last child frame is a pseudo-frame, then return its last child.
// Note that the frame we create for the generated content is also a
// pseudo-frame and so don't drill down in that case
if (lastChildFrame &&
lastChildFrame->IsPseudoFrame(aContent) &&
!lastChildFrame->IsGeneratedContentFrame()) {
return GetLastChildFrame(aPresContext, lastChildFrame, aContent);
}
return lastChildFrame;
}
return nsnull;
}
// static
nsIFrame*
nsLayoutUtils::GetBeforeFrame(nsIFrame* aFrame, nsIPresContext* aPresContext)
{
NS_PRECONDITION(aFrame, "NULL frame pointer");
#ifdef DEBUG
nsIFrame* prevInFlow = nsnull;
aFrame->GetPrevInFlow(&prevInFlow);
NS_ASSERTION(!prevInFlow, "aFrame must be first-in-flow");
#endif
nsCOMPtr<nsIContent> content;
aFrame->GetContent(getter_AddRefs(content));
nsIFrame* firstFrame = GetFirstChildFrame(aPresContext, aFrame, content);
if (firstFrame && IsGeneratedContentFor(nsnull, firstFrame,
nsCSSPseudoElements::before)) {
return firstFrame;
}
return nsnull;
}
// static
nsIFrame*
nsLayoutUtils::GetAfterFrame(nsIFrame* aFrame, nsIPresContext* aPresContext)
{
NS_PRECONDITION(aFrame, "NULL frame pointer");
nsCOMPtr<nsIContent> content;
aFrame->GetContent(getter_AddRefs(content));
nsIFrame* lastFrame = GetLastChildFrame(aPresContext, aFrame, content);
if (lastFrame && IsGeneratedContentFor(nsnull, lastFrame,
nsCSSPseudoElements::after)) {
return lastFrame;
}
return nsnull;
}
// static
nsIFrame*
nsLayoutUtils::GetPageFrame(nsIFrame* aFrame)
{
nsIFrame* frame = aFrame;
while (frame) {
nsCOMPtr<nsIAtom> type;
frame->GetFrameType(getter_AddRefs(type));
if (type.get() == nsLayoutAtoms::pageFrame) {
return frame;
}
frame->GetParent(&frame);
}
return nsnull;
}
// static
PRBool
nsLayoutUtils::IsGeneratedContentFor(nsIContent* aContent,
nsIFrame* aFrame,
nsIAtom* aPseudoElement)
{
NS_PRECONDITION(aFrame, "Must have a frame");
NS_PRECONDITION(aPseudoElement, "Must have a pseudo name");
if (!aFrame->IsGeneratedContentFrame()) {
return PR_FALSE;
}
if (aContent) {
nsCOMPtr<nsIContent> content;
aFrame->GetContent(getter_AddRefs(content));
if (content != aContent) {
return PR_FALSE;
}
}
nsStyleContext* styleContext = aFrame->GetStyleContext();
nsCOMPtr<nsIAtom> pseudoType = styleContext->GetPseudoType();
return pseudoType == aPseudoElement;
}