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gecko-dev/layout/generic/nsSpaceManager.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=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):
*
* 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 ***** */
/*
* class that manages regions of 2-D space, originally designed
* generally but actually specific to space occupied by floats
*/
#ifndef nsSpaceManager_h___
#define nsSpaceManager_h___
#include "prclist.h"
#include "nsIntervalSet.h"
#include "nsISupports.h"
#include "nsCoord.h"
#include "nsRect.h"
#include "nsVoidArray.h"
class nsIPresShell;
class nsIFrame;
struct nsSize;
struct nsHTMLReflowState;
class nsPresContext;
#define NS_SPACE_MANAGER_CACHE_SIZE 4
/**
* Information about a particular trapezoid within a band. The space described
* by the trapezoid is in one of three states:
* <ul>
* <li>available
* <li>occupied by one frame
* <li>occupied by more than one frame
* </ul>
*/
struct nsBandTrapezoid {
nscoord mTopY, mBottomY; // top and bottom y-coordinates
nscoord mTopLeftX, mBottomLeftX; // left edge x-coordinates
nscoord mTopRightX, mBottomRightX; // right edge x-coordinates
const nsSmallVoidArray* mFrames; // list of frames occupying the space
// Get the height of the trapezoid
nscoord GetHeight() const {return mBottomY - mTopY;}
// Get the bounding rect of the trapezoid
inline void GetRect(nsRect& aRect) const;
// Set the trapezoid from a rectangle
inline void operator=(const nsRect& aRect);
// Do these trapezoids have the same geometry?
inline PRBool EqualGeometry(const nsBandTrapezoid& aTrap) const;
nsBandTrapezoid()
: mTopY(0),
mBottomY(0),
mTopLeftX(0),
mBottomLeftX(0),
mTopRightX(0),
mBottomRightX(0),
mFrames(nsnull)
{
}
};
inline void nsBandTrapezoid::GetRect(nsRect& aRect) const
{
aRect.x = PR_MIN(mTopLeftX, mBottomLeftX);
aRect.y = mTopY;
aRect.width = PR_MAX(mTopRightX, mBottomRightX);
if (NS_MAXSIZE != aRect.width) {
aRect.width -= aRect.x;
}
aRect.height = (NS_MAXSIZE == mBottomY) ? NS_MAXSIZE : mBottomY - mTopY;
}
inline void nsBandTrapezoid::operator=(const nsRect& aRect)
{
mTopLeftX = mBottomLeftX = aRect.x;
mTopRightX = mBottomRightX = aRect.XMost();
mTopY = aRect.y;
mBottomY = aRect.YMost();
}
inline PRBool nsBandTrapezoid::EqualGeometry(const nsBandTrapezoid& aTrap) const
{
return (
mTopLeftX == aTrap.mTopLeftX &&
mBottomLeftX == aTrap.mBottomLeftX &&
mTopRightX == aTrap.mTopRightX &&
mBottomRightX == aTrap.mBottomRightX &&
mTopY == aTrap.mTopY &&
mBottomY == aTrap.mBottomY
);
}
/**
* Structure used for describing the space within a band.
* @see #GetBandData()
*/
struct nsBandData {
PRInt32 mCount; // [out] actual number of trapezoids in the band data
PRInt32 mSize; // [in] the size of the array (number of trapezoids)
nsBandTrapezoid* mTrapezoids; // [out] array of length 'size'
};
/**
* Class for dealing with bands of available space. The space manager
* defines a coordinate space with an origin at (0, 0) that grows down
* and to the right.
*/
class nsSpaceManager {
public:
nsSpaceManager(nsIPresShell* aPresShell, nsIFrame* aFrame);
~nsSpaceManager();
void* operator new(size_t aSize) CPP_THROW_NEW;
void operator delete(void* aPtr, size_t aSize);
static void Shutdown();
/*
* Get the frame that's associated with the space manager. This frame
* created the space manager, and the world coordinate space is
* relative to this frame.
*
* You can use QueryInterface() on this frame to get any additional
* interfaces.
*/
nsIFrame* GetFrame() const { return mFrame; }
/**
* Translate the current origin by the specified (dx, dy). This
* creates a new local coordinate space relative to the current
* coordinate space.
*/
void Translate(nscoord aDx, nscoord aDy) { mX += aDx; mY += aDy; }
/**
* Returns the current translation from local coordinate space to
* world coordinate space. This represents the accumulated calls to
* Translate().
*/
void GetTranslation(nscoord& aX, nscoord& aY) const { aX = mX; aY = mY; }
/**
* Returns the x-most rect in the space manager, or 0 if there are no
* rects.
*
* @return PR_TRUE if there are bands and PR_FALSE if there are no bands
*/
PRBool XMost(nscoord& aXMost) const;
/**
* Returns the y-most of the bottommost band or 0 if there are no bands.
*
* @return PR_TRUE if there are bands and PR_FALSE if there are no bands
*/
PRBool YMost(nscoord& aYMost) const;
/**
* Returns a band starting at the specified y-offset. The band data
* indicates which parts of the band are available, and which parts
* are unavailable
*
* The band data that is returned is in the coordinate space of the
* local coordinate system.
*
* The local coordinate space origin, the y-offset, and the max size
* describe a rectangle that's used to clip the underlying band of
* available space, i.e.
* {0, aYOffset, aMaxSize.width, aMaxSize.height} in the local
* coordinate space
*
* @param aYOffset the y-offset of where the band begins. The coordinate is
* relative to the upper-left corner of the local coordinate space
* @param aMaxSize the size to use to constrain the band data
* @param aBandData [in,out] used to return the list of trapezoids that
* describe the available space and the unavailable space
* @return NS_OK if successful and NS_ERROR_FAILURE if the band data is not
* not large enough. The 'count' member of the band data struct
* indicates how large the array of trapezoids needs to be
*/
nsresult GetBandData(nscoord aYOffset,
const nsSize& aMaxSize,
nsBandData& aBandData) const;
/**
* Add a rectangular region of unavailable space. The space is
* relative to the local coordinate system.
*
* The region is tagged with a frame
*
* @param aFrame the frame used to identify the region. Must not be NULL
* @param aUnavailableSpace the bounding rect of the unavailable space
* @return NS_OK if successful
* NS_ERROR_FAILURE if there is already a region tagged with aFrame
*/
nsresult AddRectRegion(nsIFrame* aFrame,
const nsRect& aUnavailableSpace);
/**
* Remove the regions associated with this floating frame and its
* next-sibling list. Some of the frames may never have been added;
* we just skip those. This is not fully general; it only works as
* long as the N frames to be removed are the last N frames to have
* been added; if there's a frame in the middle of them that should
* not be removed, YOU LOSE.
*
* This can only be done at the end of the life of this space manager. The only
* methods it is safe to call after this are XMost() and YMost().
*/
nsresult RemoveTrailingRegions(nsIFrame* aFrameList);
protected:
/**
* Remove the region associated with aFrane.
*
* doesn't work in the general case!
*
* Returns NS_OK if successful and NS_ERROR_INVALID_ARG if there is no region
* tagged with aFrame
*/
nsresult RemoveRegion(nsIFrame* aFrame);
public:
// Structure that stores the current state of a frame manager for
// Save/Restore purposes.
struct SavedState {
private:
nsIFrame *mLastFrame;
nscoord mX, mY;
nscoord mLowestTop;
nscoord mMaximalLeftYMost;
nscoord mMaximalRightYMost;
PRPackedBool mHaveCachedLeftYMost;
PRPackedBool mHaveCachedRightYMost;
friend class nsSpaceManager;
};
/**
* Clears the list of regions representing the unavailable space.
*/
void ClearRegions();
PRBool HasAnyFloats() { return mFrameInfoMap != nsnull; }
/**
* Methods for dealing with the propagation of float damage during
* reflow.
*/
PRBool HasFloatDamage()
{
return !mFloatDamage.IsEmpty();
}
void IncludeInDamage(nscoord aIntervalBegin, nscoord aIntervalEnd)
{
mFloatDamage.IncludeInterval(aIntervalBegin + mY, aIntervalEnd + mY);
}
PRBool IntersectsDamage(nscoord aIntervalBegin, nscoord aIntervalEnd)
{
return mFloatDamage.Intersects(aIntervalBegin + mY, aIntervalEnd + mY);
}
/**
* Saves the current state of the space manager into aState.
*/
void PushState(SavedState* aState);
/**
* Restores the space manager to the saved state.
*
* These states must be managed using stack discipline. PopState can only
* be used after PushState has been used to save the state, and it can only
* be used once --- although it can be omitted; saved states can be ignored.
* States must be popped in the reverse order they were pushed.
*/
void PopState(SavedState* aState);
/**
* Get the top of the last region placed into the space manager, to
* enforce the rule that a float can't be above an earlier float.
* Returns the minimum nscoord value if there are no regions.
*/
nscoord GetLowestRegionTop();
/**
* Return the coordinate of the lowest float matching aBreakType in this
* space manager. Returns aY if there are no matching floats.
*/
nscoord ClearFloats(nscoord aY, PRUint8 aBreakType);
#ifdef DEBUG
/**
* Dump the state of the spacemanager out to a file
*/
nsresult List(FILE* out);
#endif
protected:
// Structure that maintains information about the region associated
// with a particular frame
struct FrameInfo {
nsIFrame* const mFrame;
nsRect mRect; // rectangular region
FrameInfo* mNext;
FrameInfo(nsIFrame* aFrame, const nsRect& aRect);
#ifdef NS_BUILD_REFCNT_LOGGING
~FrameInfo();
#endif
};
public:
// Doubly linked list of band rects
struct BandRect : PRCListStr {
nscoord mLeft, mTop;
nscoord mRight, mBottom;
nsSmallVoidArray mFrames; // list of frames occupying the space
BandRect(nscoord aLeft, nscoord aTop,
nscoord aRight, nscoord aBottom,
nsIFrame* aFrame);
BandRect(nscoord aLeft, nscoord aTop,
nscoord aRight, nscoord aBottom,
nsSmallVoidArray& frames);
~BandRect();
// List operations
BandRect* Next() const {return (BandRect*)PR_NEXT_LINK(this);}
BandRect* Prev() const {return (BandRect*)PR_PREV_LINK(this);}
void InsertBefore(BandRect* aBandRect) {PR_INSERT_BEFORE(aBandRect, this);}
void InsertAfter(BandRect* aBandRect) {PR_INSERT_AFTER(aBandRect, this);}
void Remove() {PR_REMOVE_LINK(this);}
// Split the band rect into two vertically, with this band rect becoming
// the top part, and a new band rect being allocated and returned for the
// bottom part
//
// Does not insert the new band rect into the linked list
BandRect* SplitVertically(nscoord aBottom);
// Split the band rect into two horizontally, with this band rect becoming
// the left part, and a new band rect being allocated and returned for the
// right part
//
// Does not insert the new band rect into the linked list
BandRect* SplitHorizontally(nscoord aRight);
// Accessor functions
PRBool IsOccupiedBy(const nsIFrame* aFrame) const {
return (mFrames.IndexOf((void*)aFrame) != -1);
}
void AddFrame(const nsIFrame* aFrame) {
mFrames.AppendElement((void*)aFrame);
}
void RemoveFrame(const nsIFrame* aFrame) {
mFrames.RemoveElement((void*)aFrame);
}
nsIFrame * FrameAt(PRInt32 index) {
return static_cast<nsIFrame*>(mFrames.FastElementAt(index));
}
PRBool HasSameFrameList(const BandRect* aBandRect) const;
PRInt32 Length() const;
};
// Circular linked list of band rects
struct BandList : BandRect {
BandList();
// Accessors
PRBool IsEmpty() const {return PR_CLIST_IS_EMPTY((PRCListStr*)this);}
BandRect* Head() const {return (BandRect*)PR_LIST_HEAD(this);}
BandRect* Tail() const {return (BandRect*)PR_LIST_TAIL(this);}
// Operations
void Append(BandRect* aBandRect) {PR_APPEND_LINK(aBandRect, this);}
// Remove and delete all the band rects in the list
void Clear();
};
protected:
nsIFrame* const mFrame; // frame associated with the space manager
nscoord mX, mY; // translation from local to global coordinate space
BandList mBandList; // header/sentinel for circular linked list of band rects
nscoord mLowestTop; // the lowest *top*
FrameInfo* mFrameInfoMap;
nsIntervalSet mFloatDamage;
PRPackedBool mHaveCachedLeftYMost; // If true, mMaximalLeftYMost is set
PRPackedBool mHaveCachedRightYMost; // If true, mMaximalRightYMost is set
nscoord mMaximalLeftYMost; // The maximal YMost of our FrameInfo
// rects for left floats. Only makes
// sense when mHaveCachedLeftYMost is
// true.
nscoord mMaximalRightYMost; // The maximal YMost of our FrameInfo
// rects for right floats. Only makes
// sense when mHaveCachedLeftYMost is
// true.
// We keep track of the last BandRect* we worked with so that we can
// make use of locality of reference in situations where people want
// to do a bunch of operations in a row.
BandRect* mCachedBandPosition;
protected:
FrameInfo* GetFrameInfoFor(nsIFrame* aFrame);
FrameInfo* CreateFrameInfo(nsIFrame* aFrame, const nsRect& aRect);
void DestroyFrameInfo(FrameInfo*);
void ClearFrameInfo();
void ClearBandRects();
BandRect* GetNextBand(const BandRect* aBandRect) const;
BandRect* GetPrevBand(const BandRect* aBandRect) const;
void DivideBand(BandRect* aBand, nscoord aBottom);
PRBool CanJoinBands(BandRect* aBand, BandRect* aPrevBand);
PRBool JoinBands(BandRect* aBand, BandRect* aPrevBand);
void AddRectToBand(BandRect* aBand, BandRect* aBandRect);
void InsertBandRect(BandRect* aBandRect);
nsresult GetBandAvailableSpace(const BandRect* aBand,
nscoord aY,
const nsSize& aMaxSize,
nsBandData& aAvailableSpace) const;
// Return a band guaranteed to have its top at or above aYOffset or the first
// band if there is no band with its top above aYOffset. This method will
// use mCachedBandPosition to maybe get such a band that's not too far up.
// This function should not be called if there are no bands.
// This function never returns null.
BandRect* GuessBandWithTopAbove(nscoord aYOffset) const;
void SetCachedBandPosition(BandRect* aBandRect) {
NS_ASSERTION(!aBandRect ||
aBandRect == mBandList.Head() ||
aBandRect->Prev()->mBottom != aBandRect->mBottom,
"aBandRect should be first rect within its band");
mCachedBandPosition = aBandRect;
}
private:
static PRInt32 sCachedSpaceManagerCount;
static void* sCachedSpaceManagers[NS_SPACE_MANAGER_CACHE_SIZE];
nsSpaceManager(const nsSpaceManager&); // no implementation
void operator=(const nsSpaceManager&); // no implementation
};
/**
* A helper class to manage maintenance of the space manager during
* nsBlockFrame::Reflow. It automatically restores the old space
* manager in the reflow state when the object goes out of scope.
*/
class nsAutoSpaceManager {
public:
nsAutoSpaceManager(nsHTMLReflowState& aReflowState)
: mReflowState(aReflowState),
#ifdef DEBUG
mOwns(PR_TRUE),
#endif
mNew(nsnull),
mOld(nsnull) {}
~nsAutoSpaceManager();
/**
* Create a new space manager for the specified frame. This will
* `remember' the old space manager, and install the new space
* manager in the reflow state.
*/
nsresult
CreateSpaceManagerFor(nsPresContext *aPresContext,
nsIFrame *aFrame);
#ifdef DEBUG
/**
* `Orphan' any space manager that the nsAutoSpaceManager created;
* i.e., make it so that we don't destroy the space manager when we
* go out of scope.
*/
void DebugOrphanSpaceManager() { mOwns = PR_FALSE; }
#endif
protected:
nsHTMLReflowState &mReflowState;
#ifdef DEBUG
PRBool mOwns;
#endif
nsSpaceManager *mNew;
nsSpaceManager *mOld;
};
#endif /* nsSpaceManager_h___ */
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