The Tor Browser: layout/generic/nsFloatManager.h@b8a032363ba2 (annotated)

layout/generic/nsFloatManager.h@b8a032363ba2 (annotated)

layout/generic/nsFloatManager.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 // vim:cindent:ts=2:et:sw=2:
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /* class that manages rules for positioning floats */
 #ifndef nsFloatManager_h_
 #define nsFloatManager_h_
 #include "mozilla/Attributes.h"
 #include "nsIntervalSet.h"
 #include "nsCoord.h"
 #include "nsRect.h"
 #include "nsTArray.h"
 #include "nsFrameList.h" // for DEBUG_FRAME_DUMP
 class nsIPresShell;
 class nsIFrame;
 struct nsHTMLReflowState;
 class nsPresContext;
 /**
  * The available space for content not occupied by floats is divided
  * into a (vertical) sequence of rectangles.  However, we need to know
  * not only the rectangle, but also whether it was reduced (from the
  * content rectangle) by floats that actually intruded into the content
  * rectangle.
  */
 struct nsFlowAreaRect {
   nsRect mRect;
   bool mHasFloats;
   nsFlowAreaRect(nscoord aX, nscoord aY, nscoord aWidth, nscoord aHeight,
                  bool aHasFloats)
     : mRect(aX, aY, aWidth, aHeight), mHasFloats(aHasFloats) {}
 };
 #define NS_FLOAT_MANAGER_CACHE_SIZE 4
 class nsFloatManager {
 public:
   nsFloatManager(nsIPresShell* aPresShell);
   ~nsFloatManager();
   void* operator new(size_t aSize) CPP_THROW_NEW;
   void operator delete(void* aPtr, size_t aSize);
   static void Shutdown();
   /**
    * Get float region stored on the frame. (Defaults to mRect if it's
    * not there.) The float region is the area impacted by this float;
    * the coordinates are relative to the containing block frame.
    */
   static nsRect GetRegionFor(nsIFrame* aFloatFrame);
   /**
    * Calculate the float region for this frame using aMargin and the
    * frame's mRect. The region includes the margins around the float,
    * but doesn't include the relative offsets.
    * Note that if the frame is or has a continuation, aMargin's top
    * and/or bottom must be zeroed by the caller.
    */
   static nsRect CalculateRegionFor(nsIFrame* aFloatFrame,
                                    const nsMargin& aMargin);
   /**
    * Store the float region on the frame. The region is stored
    * as a delta against the mRect, so repositioning the frame will
    * also reposition the float region.
    */
   static void StoreRegionFor(nsIFrame* aFloat, nsRect& aRegion);
   // Structure that stores the current state of a frame manager for
   // Save/Restore purposes.
   struct SavedState;
   friend struct SavedState;
   struct SavedState {
   private:
     uint32_t mFloatInfoCount;
     nscoord mX, mY;
     bool mPushedLeftFloatPastBreak;
     bool mPushedRightFloatPastBreak;
     bool mSplitLeftFloatAcrossBreak;
     bool mSplitRightFloatAcrossBreak;
     friend class nsFloatManager;
   };
   /**
    * 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; }
   /**
    * Get information about the area available to content that flows
    * around floats.  Two different types of space can be requested:
    *   BAND_FROM_POINT: returns the band containing vertical coordinate
    *     |aY| (though actually with the top truncated to begin at aY),
    *     but up to at most |aHeight| (which may be nscoord_MAX).
    *     This will return the tallest rectangle whose top is |aY| and in
    *     which there are no changes in what floats are on the sides of
    *     that rectangle, but will limit the height of the rectangle to
    *     |aHeight|.  The left and right edges of the rectangle give the
    *     area available for line boxes in that space.  The width of this
    *     resulting rectangle will not be negative.
    *   WIDTH_WITHIN_HEIGHT: This returns a rectangle whose top is aY and
    *     whose height is exactly aHeight.  Its left and right edges give
    *     the left and right edges of the space that can be used for line
    *     boxes *throughout* that space.  (It is possible that more
    *     horizontal space could be used in part of the space if a float
    *     begins or ends in it.)  The width of the resulting rectangle
    *     can be negative.
    *
    * @param aY [in] vertical coordinate for top of available space
    *           desired
    * @param aHeight [in] see above
    * @param aContentArea [in] an nsRect representing the content area
    * @param aState [in] If null, use the current state, otherwise, do
    *                    computation based only on floats present in the given
    *                    saved state.
    * @return An nsFlowAreaRect whose:
    *           mRect is the resulting rectangle for line boxes.  It will not
    *             extend beyond aContentArea's horizontal bounds, but may be
    *             narrower when floats are present.
    *          mBandHasFloats is whether there are floats at the sides of the
    *            return value including those that do not reduce the line box
    *            width at all (because they are entirely in the margins)
    *
    * aY and aAvailSpace are positioned relative to the current translation
    */
   enum BandInfoType { BAND_FROM_POINT, WIDTH_WITHIN_HEIGHT };
   nsFlowAreaRect GetFlowArea(nscoord aY, BandInfoType aInfoType,
                              nscoord aHeight, nsRect aContentArea,
                              SavedState* aState) const;
   /**
    * Add a float that comes after all floats previously added.  Its top
    * must be even with or below the top of all previous floats.
    *
    * aMarginRect is relative to the current translation.  The caller
    * must ensure aMarginRect.height >= 0 and aMarginRect.width >= 0.
    */
   nsresult AddFloat(nsIFrame* aFloatFrame, const nsRect& aMarginRect);
   /**
    * Notify that we tried to place a float that could not fit at all and
    * had to be pushed to the next page/column?  (If so, we can't place
    * any more floats in this page/column because of the rule that the
    * top of a float cannot be above the top of an earlier float.  It
    * also means that any clear needs to continue to the next column.)
    */
   void SetPushedLeftFloatPastBreak()
     { mPushedLeftFloatPastBreak = true; }
   void SetPushedRightFloatPastBreak()
     { mPushedRightFloatPastBreak = true; }
   /**
    * Notify that we split a float, with part of it needing to be pushed
    * to the next page/column.  (This means that any 'clear' needs to
    * continue to the next page/column.)
    */
   void SetSplitLeftFloatAcrossBreak()
     { mSplitLeftFloatAcrossBreak = true; }
   void SetSplitRightFloatAcrossBreak()
     { mSplitRightFloatAcrossBreak = true; }
   /**
    * 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.
    */
   nsresult RemoveTrailingRegions(nsIFrame* aFrameList);
 private:
   struct FloatInfo;
 public:
   bool HasAnyFloats() const { return !mFloats.IsEmpty(); }
   /**
    * Methods for dealing with the propagation of float damage during
    * reflow.
    */
   bool HasFloatDamage() const
   {
     return !mFloatDamage.IsEmpty();
   }
   void IncludeInDamage(nscoord aIntervalBegin, nscoord aIntervalEnd)
   {
     mFloatDamage.IncludeInterval(aIntervalBegin + mY, aIntervalEnd + mY);
   }
   bool IntersectsDamage(nscoord aIntervalBegin, nscoord aIntervalEnd) const
   {
     return mFloatDamage.Intersects(aIntervalBegin + mY, aIntervalEnd + mY);
   }
   /**
    * Saves the current state of the float manager into aState.
    */
   void PushState(SavedState* aState);
   /**
    * Restores the float 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.  A
    * call to PopState invalidates any saved states Pushed after the
    * state passed to PopState was pushed.
    */
   void PopState(SavedState* aState);
   /**
    * Get the top of the last float placed into the float manager, to
    * enforce the rule that a float can't be above an earlier float.
    * Returns the minimum nscoord value if there are no floats.
    *
    * The result is relative to the current translation.
    */
   nscoord GetLowestFloatTop() const;
   /**
    * Return the coordinate of the lowest float matching aBreakType in this
    * float manager. Returns aY if there are no matching floats.
    *
    * Both aY and the result are relative to the current translation.
    */
   enum {
     // Tell ClearFloats not to push to nscoord_MAX when floats have been
     // pushed to the next page/column.
     DONT_CLEAR_PUSHED_FLOATS = (1<<0)
   };
   nscoord ClearFloats(nscoord aY, uint8_t aBreakType, uint32_t aFlags = 0) const;
   /**
    * Checks if clear would pass into the floats' BFC's next-in-flow,
    * i.e. whether floats affecting this clear have continuations.
    */
   bool ClearContinues(uint8_t aBreakType) const;
   void AssertStateMatches(SavedState *aState) const
   {
     NS_ASSERTION(aState->mX == mX && aState->mY == mY &&
                  aState->mPushedLeftFloatPastBreak ==
                    mPushedLeftFloatPastBreak &&
                  aState->mPushedRightFloatPastBreak ==
                    mPushedRightFloatPastBreak &&
                  aState->mSplitLeftFloatAcrossBreak ==
                    mSplitLeftFloatAcrossBreak &&
                  aState->mSplitRightFloatAcrossBreak ==
                    mSplitRightFloatAcrossBreak &&
                  aState->mFloatInfoCount == mFloats.Length(),
                  "float manager state should match saved state");
   }
 #ifdef DEBUG_FRAME_DUMP
   /**
    * Dump the state of the float manager out to a file.
    */
   nsresult List(FILE* out) const;
 #endif
 private:
   struct FloatInfo {
     nsIFrame *const mFrame;
     nsRect mRect;
     // The lowest bottoms of left/right floats up to and including this one.
     nscoord mLeftYMost, mRightYMost;
     FloatInfo(nsIFrame* aFrame, const nsRect& aRect);
 #ifdef NS_BUILD_REFCNT_LOGGING
     FloatInfo(const FloatInfo& aOther);
     ~FloatInfo();
 #endif
   };
   nscoord         mX, mY;     // translation from local to global coordinate space
   nsTArray<FloatInfo> mFloats;
   nsIntervalSet   mFloatDamage;
   // Did we try to place a float that could not fit at all and had to be
   // pushed to the next page/column?  If so, we can't place any more
   // floats in this page/column because of the rule that the top of a
   // float cannot be above the top of an earlier float.  And we also
   // need to apply this information to 'clear', and thus need to
   // separate left and right floats.
   bool mPushedLeftFloatPastBreak;
   bool mPushedRightFloatPastBreak;
   // Did we split a float, with part of it needing to be pushed to the
   // next page/column.  This means that any 'clear' needs to continue to
   // the next page/column.
   bool mSplitLeftFloatAcrossBreak;
   bool mSplitRightFloatAcrossBreak;
   static int32_t sCachedFloatManagerCount;
   static void* sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE];
   nsFloatManager(const nsFloatManager&) MOZ_DELETE;
   void operator=(const nsFloatManager&) MOZ_DELETE;
 };
 /**
  * A helper class to manage maintenance of the float manager during
  * nsBlockFrame::Reflow. It automatically restores the old float
  * manager in the reflow state when the object goes out of scope.
  */
 class nsAutoFloatManager {
 public:
   nsAutoFloatManager(nsHTMLReflowState& aReflowState)
     : mReflowState(aReflowState),
       mNew(nullptr),
       mOld(nullptr) {}
   ~nsAutoFloatManager();
   /**
    * Create a new float manager for the specified frame. This will
    * `remember' the old float manager, and install the new float
    * manager in the reflow state.
    */
   nsresult
   CreateFloatManager(nsPresContext *aPresContext);
 protected:
   nsHTMLReflowState &mReflowState;
   nsFloatManager *mNew;
   nsFloatManager *mOld;
 };
 #endif /* !defined(nsFloatManager_h_) */

The Tor Browser / annotate

layout/generic/nsFloatManager.h@b8a032363ba2 (annotated)

layout/generic/nsFloatManager.h