LCOV - code coverage report
Current view: directory - layout/generic - nsFloatManager.h (source / functions) Found Hit Coverage
Test: app.info Lines: 26 0 0.0 %
Date: 2012-06-02 Functions: 14 0 0.0 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2                 : // vim:cindent:ts=2:et:sw=2:
       3                 : /* ***** BEGIN LICENSE BLOCK *****
       4                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       5                 :  *
       6                 :  * The contents of this file are subject to the Mozilla Public License Version
       7                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       8                 :  * the License. You may obtain a copy of the License at
       9                 :  * http://www.mozilla.org/MPL/
      10                 :  *
      11                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      12                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      13                 :  * for the specific language governing rights and limitations under the
      14                 :  * License.
      15                 :  *
      16                 :  * The Original Code is mozilla.org code.
      17                 :  *
      18                 :  * The Initial Developer of the Original Code is
      19                 :  * Netscape Communications Corporation.
      20                 :  * Portions created by the Initial Developer are Copyright (C) 1998
      21                 :  * the Initial Developer. All Rights Reserved.
      22                 :  *
      23                 :  * Contributor(s):
      24                 :  *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
      25                 :  *
      26                 :  * Alternatively, the contents of this file may be used under the terms of
      27                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
      28                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      29                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      30                 :  * of those above. If you wish to allow use of your version of this file only
      31                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      32                 :  * use your version of this file under the terms of the MPL, indicate your
      33                 :  * decision by deleting the provisions above and replace them with the notice
      34                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      35                 :  * the provisions above, a recipient may use your version of this file under
      36                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      37                 :  *
      38                 :  * ***** END LICENSE BLOCK ***** */
      39                 : 
      40                 : /* class that manages rules for positioning floats */
      41                 : 
      42                 : #ifndef nsFloatManager_h_
      43                 : #define nsFloatManager_h_
      44                 : 
      45                 : #include "mozilla/Attributes.h"
      46                 : 
      47                 : #include "nsIntervalSet.h"
      48                 : #include "nsCoord.h"
      49                 : #include "nsRect.h"
      50                 : #include "nsTArray.h"
      51                 : 
      52                 : class nsIPresShell;
      53                 : class nsIFrame;
      54                 : struct nsHTMLReflowState;
      55                 : class nsPresContext;
      56                 : 
      57                 : /**
      58                 :  * The available space for content not occupied by floats is divided
      59                 :  * into a (vertical) sequence of rectangles.  However, we need to know
      60                 :  * not only the rectangle, but also whether it was reduced (from the
      61                 :  * content rectangle) by floats that actually intruded into the content
      62                 :  * rectangle.
      63                 :  */
      64               0 : struct nsFlowAreaRect {
      65                 :   nsRect mRect;
      66                 :   bool mHasFloats;
      67                 : 
      68               0 :   nsFlowAreaRect(nscoord aX, nscoord aY, nscoord aWidth, nscoord aHeight,
      69                 :                  bool aHasFloats)
      70               0 :     : mRect(aX, aY, aWidth, aHeight), mHasFloats(aHasFloats) {}
      71                 : };
      72                 : 
      73                 : #define NS_FLOAT_MANAGER_CACHE_SIZE 4
      74                 : 
      75                 : class nsFloatManager {
      76                 : public:
      77                 :   nsFloatManager(nsIPresShell* aPresShell);
      78                 :   ~nsFloatManager();
      79                 : 
      80                 :   void* operator new(size_t aSize) CPP_THROW_NEW;
      81                 :   void operator delete(void* aPtr, size_t aSize);
      82                 : 
      83                 :   static void Shutdown();
      84                 : 
      85                 :   /**
      86                 :    * Get float region stored on the frame. (Defaults to mRect if it's
      87                 :    * not there.) The float region is the area impacted by this float;
      88                 :    * the coordinates are relative to the containing block frame.
      89                 :    */
      90                 :   static nsRect GetRegionFor(nsIFrame* aFloatFrame);
      91                 :   /**
      92                 :    * Calculate the float region for this frame using aMargin and the
      93                 :    * frame's mRect. The region includes the margins around the float,
      94                 :    * but doesn't include the relative offsets.
      95                 :    * Note that if the frame is or has a continuation, aMargin's top
      96                 :    * and/or bottom must be zeroed by the caller.
      97                 :    */
      98                 :   static nsRect CalculateRegionFor(nsIFrame* aFloatFrame,
      99                 :                                    const nsMargin& aMargin);
     100                 :   /**
     101                 :    * Store the float region on the frame. The region is stored
     102                 :    * as a delta against the mRect, so repositioning the frame will
     103                 :    * also reposition the float region.
     104                 :    */
     105                 :   static void StoreRegionFor(nsIFrame* aFloat, nsRect& aRegion);
     106                 : 
     107                 :   // Structure that stores the current state of a frame manager for
     108                 :   // Save/Restore purposes.
     109                 :   struct SavedState;
     110                 :   friend struct SavedState;
     111                 :   struct SavedState {
     112                 :   private:
     113                 :     PRUint32 mFloatInfoCount;
     114                 :     nscoord mX, mY;
     115                 :     bool mPushedLeftFloatPastBreak;
     116                 :     bool mPushedRightFloatPastBreak;
     117                 :     bool mSplitLeftFloatAcrossBreak;
     118                 :     bool mSplitRightFloatAcrossBreak;
     119                 : 
     120                 :     friend class nsFloatManager;
     121                 :   };
     122                 : 
     123                 :   /**
     124                 :    * Translate the current origin by the specified (dx, dy). This
     125                 :    * creates a new local coordinate space relative to the current
     126                 :    * coordinate space.
     127                 :    */
     128               0 :   void Translate(nscoord aDx, nscoord aDy) { mX += aDx; mY += aDy; }
     129                 : 
     130                 :   /**
     131                 :    * Returns the current translation from local coordinate space to
     132                 :    * world coordinate space. This represents the accumulated calls to
     133                 :    * Translate().
     134                 :    */
     135               0 :   void GetTranslation(nscoord& aX, nscoord& aY) const { aX = mX; aY = mY; }
     136                 : 
     137                 :   /**
     138                 :    * Get information about the area available to content that flows
     139                 :    * around floats.  Two different types of space can be requested:
     140                 :    *   BAND_FROM_POINT: returns the band containing vertical coordinate
     141                 :    *     |aY| (though actually with the top truncated to begin at aY),
     142                 :    *     but up to at most |aHeight| (which may be nscoord_MAX).
     143                 :    *     This will return the tallest rectangle whose top is |aY| and in
     144                 :    *     which there are no changes in what floats are on the sides of
     145                 :    *     that rectangle, but will limit the height of the rectangle to
     146                 :    *     |aHeight|.  The left and right edges of the rectangle give the
     147                 :    *     area available for line boxes in that space.  The width of this
     148                 :    *     resulting rectangle will not be negative.
     149                 :    *   WIDTH_WITHIN_HEIGHT: This returns a rectangle whose top is aY and
     150                 :    *     whose height is exactly aHeight.  Its left and right edges give
     151                 :    *     the left and right edges of the space that can be used for line
     152                 :    *     boxes *throughout* that space.  (It is possible that more
     153                 :    *     horizontal space could be used in part of the space if a float
     154                 :    *     begins or ends in it.)  The width of the resulting rectangle
     155                 :    *     can be negative.
     156                 :    *
     157                 :    * @param aY [in] vertical coordinate for top of available space
     158                 :    *           desired
     159                 :    * @param aHeight [in] see above
     160                 :    * @param aContentArea [in] an nsRect representing the content area
     161                 :    * @param aState [in] If null, use the current state, otherwise, do
     162                 :    *                    computation based only on floats present in the given
     163                 :    *                    saved state.
     164                 :    * @return An nsFlowAreaRect whose:
     165                 :    *           mRect is the resulting rectangle for line boxes.  It will not
     166                 :    *             extend beyond aContentArea's horizontal bounds, but may be
     167                 :    *             narrower when floats are present.
     168                 :    *          mBandHasFloats is whether there are floats at the sides of the
     169                 :    *            return value including those that do not reduce the line box
     170                 :    *            width at all (because they are entirely in the margins)
     171                 :    *
     172                 :    * aY and aAvailSpace are positioned relative to the current translation
     173                 :    */
     174                 :   enum BandInfoType { BAND_FROM_POINT, WIDTH_WITHIN_HEIGHT };
     175                 :   nsFlowAreaRect GetFlowArea(nscoord aY, BandInfoType aInfoType,
     176                 :                              nscoord aHeight, nsRect aContentArea,
     177                 :                              SavedState* aState) const;
     178                 : 
     179                 :   /**
     180                 :    * Add a float that comes after all floats previously added.  Its top
     181                 :    * must be even with or below the top of all previous floats.
     182                 :    *
     183                 :    * aMarginRect is relative to the current translation.  The caller
     184                 :    * must ensure aMarginRect.height >= 0 and aMarginRect.width >= 0.
     185                 :    */
     186                 :   nsresult AddFloat(nsIFrame* aFloatFrame, const nsRect& aMarginRect);
     187                 : 
     188                 :   /**
     189                 :    * Notify that we tried to place a float that could not fit at all and
     190                 :    * had to be pushed to the next page/column?  (If so, we can't place
     191                 :    * any more floats in this page/column because of the rule that the
     192                 :    * top of a float cannot be above the top of an earlier float.  It
     193                 :    * also means that any clear needs to continue to the next column.)
     194                 :    */
     195               0 :   void SetPushedLeftFloatPastBreak()
     196               0 :     { mPushedLeftFloatPastBreak = true; }
     197               0 :   void SetPushedRightFloatPastBreak()
     198               0 :     { mPushedRightFloatPastBreak = true; }
     199                 : 
     200                 :   /**
     201                 :    * Notify that we split a float, with part of it needing to be pushed
     202                 :    * to the next page/column.  (This means that any 'clear' needs to
     203                 :    * continue to the next page/column.)
     204                 :    */
     205               0 :   void SetSplitLeftFloatAcrossBreak()
     206               0 :     { mSplitLeftFloatAcrossBreak = true; }
     207               0 :   void SetSplitRightFloatAcrossBreak()
     208               0 :     { mSplitRightFloatAcrossBreak = true; }
     209                 : 
     210                 :   /**
     211                 :    * Remove the regions associated with this floating frame and its
     212                 :    * next-sibling list.  Some of the frames may never have been added;
     213                 :    * we just skip those. This is not fully general; it only works as
     214                 :    * long as the N frames to be removed are the last N frames to have
     215                 :    * been added; if there's a frame in the middle of them that should
     216                 :    * not be removed, YOU LOSE.
     217                 :    */
     218                 :   nsresult RemoveTrailingRegions(nsIFrame* aFrameList);
     219                 : 
     220                 : private:
     221                 :   struct FloatInfo;
     222                 : public:
     223                 : 
     224               0 :   bool HasAnyFloats() const { return !mFloats.IsEmpty(); }
     225                 : 
     226                 :   /**
     227                 :    * Methods for dealing with the propagation of float damage during
     228                 :    * reflow.
     229                 :    */
     230               0 :   bool HasFloatDamage() const
     231                 :   {
     232               0 :     return !mFloatDamage.IsEmpty();
     233                 :   }
     234                 : 
     235               0 :   void IncludeInDamage(nscoord aIntervalBegin, nscoord aIntervalEnd)
     236                 :   {
     237               0 :     mFloatDamage.IncludeInterval(aIntervalBegin + mY, aIntervalEnd + mY);
     238               0 :   }
     239                 : 
     240               0 :   bool IntersectsDamage(nscoord aIntervalBegin, nscoord aIntervalEnd) const
     241                 :   {
     242               0 :     return mFloatDamage.Intersects(aIntervalBegin + mY, aIntervalEnd + mY);
     243                 :   }
     244                 : 
     245                 :   /**
     246                 :    * Saves the current state of the float manager into aState.
     247                 :    */
     248                 :   void PushState(SavedState* aState);
     249                 : 
     250                 :   /**
     251                 :    * Restores the float manager to the saved state.
     252                 :    * 
     253                 :    * These states must be managed using stack discipline. PopState can only
     254                 :    * be used after PushState has been used to save the state, and it can only
     255                 :    * be used once --- although it can be omitted; saved states can be ignored.
     256                 :    * States must be popped in the reverse order they were pushed.  A
     257                 :    * call to PopState invalidates any saved states Pushed after the
     258                 :    * state passed to PopState was pushed.
     259                 :    */
     260                 :   void PopState(SavedState* aState);
     261                 : 
     262                 :   /**
     263                 :    * Get the top of the last float placed into the float manager, to
     264                 :    * enforce the rule that a float can't be above an earlier float.
     265                 :    * Returns the minimum nscoord value if there are no floats.
     266                 :    *
     267                 :    * The result is relative to the current translation.
     268                 :    */
     269                 :   nscoord GetLowestFloatTop() const;
     270                 : 
     271                 :   /**
     272                 :    * Return the coordinate of the lowest float matching aBreakType in this
     273                 :    * float manager. Returns aY if there are no matching floats.
     274                 :    *
     275                 :    * Both aY and the result are relative to the current translation.
     276                 :    */
     277                 :   enum {
     278                 :     // Tell ClearFloats not to push to nscoord_MAX when floats have been
     279                 :     // pushed to the next page/column.
     280                 :     DONT_CLEAR_PUSHED_FLOATS = (1<<0)
     281                 :   };
     282                 :   nscoord ClearFloats(nscoord aY, PRUint8 aBreakType, PRUint32 aFlags = 0) const;
     283                 : 
     284                 :   /**
     285                 :    * Checks if clear would pass into the floats' BFC's next-in-flow,
     286                 :    * i.e. whether floats affecting this clear have continuations.
     287                 :    */
     288                 :   bool ClearContinues(PRUint8 aBreakType) const;
     289                 : 
     290               0 :   void AssertStateMatches(SavedState *aState) const
     291                 :   {
     292               0 :     NS_ASSERTION(aState->mX == mX && aState->mY == mY &&
     293                 :                  aState->mPushedLeftFloatPastBreak ==
     294                 :                    mPushedLeftFloatPastBreak &&
     295                 :                  aState->mPushedRightFloatPastBreak ==
     296                 :                    mPushedRightFloatPastBreak &&
     297                 :                  aState->mSplitLeftFloatAcrossBreak ==
     298                 :                    mSplitLeftFloatAcrossBreak &&
     299                 :                  aState->mSplitRightFloatAcrossBreak ==
     300                 :                    mSplitRightFloatAcrossBreak &&
     301                 :                  aState->mFloatInfoCount == mFloats.Length(),
     302                 :                  "float manager state should match saved state");
     303               0 :   }
     304                 : 
     305                 : #ifdef DEBUG
     306                 :   /**
     307                 :    * Dump the state of the float manager out to a file.
     308                 :    */
     309                 :   nsresult List(FILE* out) const;
     310                 : #endif
     311                 : 
     312                 : private:
     313                 : 
     314                 :   struct FloatInfo {
     315                 :     nsIFrame *const mFrame;
     316                 :     nsRect mRect;
     317                 :     // The lowest bottoms of left/right floats up to and including this one.
     318                 :     nscoord mLeftYMost, mRightYMost;
     319                 : 
     320                 :     FloatInfo(nsIFrame* aFrame, const nsRect& aRect);
     321                 : #ifdef NS_BUILD_REFCNT_LOGGING
     322                 :     FloatInfo(const FloatInfo& aOther);
     323                 :     ~FloatInfo();
     324                 : #endif
     325                 :   };
     326                 : 
     327                 :   nscoord         mX, mY;     // translation from local to global coordinate space
     328                 :   nsTArray<FloatInfo> mFloats;
     329                 :   nsIntervalSet   mFloatDamage;
     330                 : 
     331                 :   // Did we try to place a float that could not fit at all and had to be
     332                 :   // pushed to the next page/column?  If so, we can't place any more
     333                 :   // floats in this page/column because of the rule that the top of a
     334                 :   // float cannot be above the top of an earlier float.  And we also
     335                 :   // need to apply this information to 'clear', and thus need to
     336                 :   // separate left and right floats.
     337                 :   bool mPushedLeftFloatPastBreak;
     338                 :   bool mPushedRightFloatPastBreak;
     339                 : 
     340                 :   // Did we split a float, with part of it needing to be pushed to the
     341                 :   // next page/column.  This means that any 'clear' needs to continue to
     342                 :   // the next page/column.
     343                 :   bool mSplitLeftFloatAcrossBreak;
     344                 :   bool mSplitRightFloatAcrossBreak;
     345                 : 
     346                 :   static PRInt32 sCachedFloatManagerCount;
     347                 :   static void* sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE];
     348                 : 
     349                 :   nsFloatManager(const nsFloatManager&) MOZ_DELETE;
     350                 :   void operator=(const nsFloatManager&) MOZ_DELETE;
     351                 : };
     352                 : 
     353                 : /**
     354                 :  * A helper class to manage maintenance of the float manager during
     355                 :  * nsBlockFrame::Reflow. It automatically restores the old float
     356                 :  * manager in the reflow state when the object goes out of scope.
     357                 :  */
     358                 : class nsAutoFloatManager {
     359                 : public:
     360               0 :   nsAutoFloatManager(nsHTMLReflowState& aReflowState)
     361                 :     : mReflowState(aReflowState),
     362                 :       mNew(nsnull),
     363               0 :       mOld(nsnull) {}
     364                 : 
     365                 :   ~nsAutoFloatManager();
     366                 : 
     367                 :   /**
     368                 :    * Create a new float manager for the specified frame. This will
     369                 :    * `remember' the old float manager, and install the new float
     370                 :    * manager in the reflow state.
     371                 :    */
     372                 :   nsresult
     373                 :   CreateFloatManager(nsPresContext *aPresContext);
     374                 : 
     375                 : protected:
     376                 :   nsHTMLReflowState &mReflowState;
     377                 :   nsFloatManager *mNew;
     378                 :   nsFloatManager *mOld;
     379                 : };
     380                 : 
     381                 : #endif /* !defined(nsFloatManager_h_) */

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