LCOV - code coverage report
Current view: directory - content/svg/content/src - SVGLengthList.h (source / functions) Found Hit Coverage
Test: app.info Lines: 74 0 0.0 %
Date: 2012-06-02 Functions: 29 0 0.0 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2                 : /* ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is Mozilla SVG Project code.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is the Mozilla Foundation.
      18                 :  * Portions created by the Initial Developer are Copyright (C) 2010
      19                 :  * the Initial Developer. All Rights Reserved.
      20                 :  *
      21                 :  * Contributor(s):
      22                 :  *
      23                 :  * Alternatively, the contents of this file may be used under the terms of
      24                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      25                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      26                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      27                 :  * of those above. If you wish to allow use of your version of this file only
      28                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      29                 :  * use your version of this file under the terms of the MPL, indicate your
      30                 :  * decision by deleting the provisions above and replace them with the notice
      31                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      32                 :  * the provisions above, a recipient may use your version of this file under
      33                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      34                 :  *
      35                 :  * ***** END LICENSE BLOCK ***** */
      36                 : 
      37                 : #ifndef MOZILLA_SVGLENGTHLIST_H__
      38                 : #define MOZILLA_SVGLENGTHLIST_H__
      39                 : 
      40                 : #include "nsCOMPtr.h"
      41                 : #include "nsDebug.h"
      42                 : #include "nsIContent.h"
      43                 : #include "nsINode.h"
      44                 : #include "nsIWeakReferenceUtils.h"
      45                 : #include "nsSVGElement.h"
      46                 : #include "nsTArray.h"
      47                 : #include "SVGLength.h"
      48                 : 
      49                 : namespace mozilla {
      50                 : 
      51                 : /**
      52                 :  * ATTENTION! WARNING! WATCH OUT!!
      53                 :  *
      54                 :  * Consumers that modify objects of this type absolutely MUST keep the DOM
      55                 :  * wrappers for those lists (if any) in sync!! That's why this class is so
      56                 :  * locked down.
      57                 :  *
      58                 :  * The DOM wrapper class for this class is DOMSVGLengthList.
      59                 :  */
      60                 : class SVGLengthList
      61                 : {
      62                 :   friend class SVGAnimatedLengthList;
      63                 :   friend class DOMSVGLengthList;
      64                 :   friend class DOMSVGLength;
      65                 : 
      66                 : public:
      67                 : 
      68               0 :   SVGLengthList(){}
      69               0 :   ~SVGLengthList(){}
      70                 : 
      71                 :   // Only methods that don't make/permit modification to this list are public.
      72                 :   // Only our friend classes can access methods that may change us.
      73                 : 
      74                 :   /// This may return an incomplete string on OOM, but that's acceptable.
      75                 :   void GetValueAsString(nsAString& aValue) const;
      76                 : 
      77               0 :   bool IsEmpty() const {
      78               0 :     return mLengths.IsEmpty();
      79                 :   }
      80                 : 
      81               0 :   PRUint32 Length() const {
      82               0 :     return mLengths.Length();
      83                 :   }
      84                 : 
      85               0 :   const SVGLength& operator[](PRUint32 aIndex) const {
      86               0 :     return mLengths[aIndex];
      87                 :   }
      88                 : 
      89                 :   bool operator==(const SVGLengthList& rhs) const;
      90                 : 
      91               0 :   bool SetCapacity(PRUint32 size) {
      92               0 :     return mLengths.SetCapacity(size);
      93                 :   }
      94                 : 
      95                 :   void Compact() {
      96                 :     mLengths.Compact();
      97                 :   }
      98                 : 
      99                 :   // Access to methods that can modify objects of this type is deliberately
     100                 :   // limited. This is to reduce the chances of someone modifying objects of
     101                 :   // this type without taking the necessary steps to keep DOM wrappers in sync.
     102                 :   // If you need wider access to these methods, consider adding a method to
     103                 :   // SVGAnimatedLengthList and having that class act as an intermediary so it
     104                 :   // can take care of keeping DOM wrappers in sync.
     105                 : 
     106                 : protected:
     107                 : 
     108                 :   /**
     109                 :    * This may fail on OOM if the internal capacity needs to be increased, in
     110                 :    * which case the list will be left unmodified.
     111                 :    */
     112                 :   nsresult CopyFrom(const SVGLengthList& rhs);
     113                 : 
     114               0 :   SVGLength& operator[](PRUint32 aIndex) {
     115               0 :     return mLengths[aIndex];
     116                 :   }
     117                 : 
     118                 :   /**
     119                 :    * This may fail (return false) on OOM if the internal capacity is being
     120                 :    * increased, in which case the list will be left unmodified.
     121                 :    */
     122               0 :   bool SetLength(PRUint32 aNumberOfItems) {
     123               0 :     return mLengths.SetLength(aNumberOfItems);
     124                 :   }
     125                 : 
     126                 : private:
     127                 : 
     128                 :   // Marking the following private only serves to show which methods are only
     129                 :   // used by our friend classes (as opposed to our subclasses) - it doesn't
     130                 :   // really provide additional safety.
     131                 : 
     132                 :   nsresult SetValueFromString(const nsAString& aValue);
     133                 : 
     134               0 :   void Clear() {
     135               0 :     mLengths.Clear();
     136               0 :   }
     137                 : 
     138               0 :   bool InsertItem(PRUint32 aIndex, const SVGLength &aLength) {
     139               0 :     if (aIndex >= mLengths.Length()) aIndex = mLengths.Length();
     140               0 :     return !!mLengths.InsertElementAt(aIndex, aLength);
     141                 :   }
     142                 : 
     143                 :   void ReplaceItem(PRUint32 aIndex, const SVGLength &aLength) {
     144                 :     NS_ABORT_IF_FALSE(aIndex < mLengths.Length(),
     145                 :                       "DOM wrapper caller should have raised INDEX_SIZE_ERR");
     146                 :     mLengths[aIndex] = aLength;
     147                 :   }
     148                 : 
     149               0 :   void RemoveItem(PRUint32 aIndex) {
     150               0 :     NS_ABORT_IF_FALSE(aIndex < mLengths.Length(),
     151                 :                       "DOM wrapper caller should have raised INDEX_SIZE_ERR");
     152               0 :     mLengths.RemoveElementAt(aIndex);
     153               0 :   }
     154                 : 
     155               0 :   bool AppendItem(SVGLength aLength) {
     156               0 :     return !!mLengths.AppendElement(aLength);
     157                 :   }
     158                 : 
     159                 : protected:
     160                 : 
     161                 :   /* Rationale for using nsTArray<SVGLength> and not nsTArray<SVGLength, 1>:
     162                 :    *
     163                 :    * It might seem like we should use nsAutoTArray<SVGLength, 1> instead of
     164                 :    * nsTArray<SVGLength>. That would preallocate space for one SVGLength and
     165                 :    * avoid an extra memory allocation call in the common case of the 'x'
     166                 :    * and 'y' attributes each containing a single length (and the 'dx' and 'dy'
     167                 :    * attributes being empty). However, consider this:
     168                 :    *
     169                 :    * An empty nsTArray uses sizeof(Header*). An nsAutoTArray<class E,
     170                 :    * PRUint32 N> on the other hand uses sizeof(Header*) +
     171                 :    * (2 * sizeof(PRUint32)) + (N * sizeof(E)), which for one SVGLength is
     172                 :    * sizeof(Header*) + 16 bytes.
     173                 :    *
     174                 :    * Now consider that for text elements we have four length list attributes
     175                 :    * (x, y, dx, dy), each of which can have a baseVal and an animVal list. If
     176                 :    * we were to go the nsAutoTArray<SVGLength, 1> route for each of these, we'd
     177                 :    * end up using at least 160 bytes for these four attributes alone, even
     178                 :    * though we only need storage for two SVGLengths (16 bytes) in the common
     179                 :    * case!!
     180                 :    *
     181                 :    * A compromise might be to template SVGLengthList to allow
     182                 :    * SVGAnimatedLengthList to preallocate space for an SVGLength for the
     183                 :    * baseVal lists only, and that would cut the space used by the four
     184                 :    * attributes to 96 bytes. Taking that even further and templating
     185                 :    * SVGAnimatedLengthList too in order to only use nsTArray for 'dx' and 'dy'
     186                 :    * would reduce the storage further to 64 bytes. Having different types makes
     187                 :    * things more complicated for code that needs to look at the lists though.
     188                 :    * In fact it also makes things more complicated when it comes to storing the
     189                 :    * lists.
     190                 :    *
     191                 :    * It may be worth considering using nsAttrValue for length lists instead of
     192                 :    * storing them directly on the element.
     193                 :    */
     194                 :   nsTArray<SVGLength> mLengths;
     195                 : };
     196                 : 
     197                 : 
     198                 : /**
     199                 :  * This SVGLengthList subclass is for SVGLengthListSMILType which needs to know
     200                 :  * which element and attribute a length list belongs to so that it can convert
     201                 :  * between unit types if necessary.
     202                 :  */
     203                 : class SVGLengthListAndInfo : public SVGLengthList
     204               0 : {
     205                 : public:
     206                 : 
     207               0 :   SVGLengthListAndInfo()
     208                 :     : mElement(nsnull)
     209                 :     , mAxis(0)
     210               0 :     , mCanZeroPadList(false)
     211               0 :   {}
     212                 : 
     213                 :   SVGLengthListAndInfo(nsSVGElement *aElement, PRUint8 aAxis, bool aCanZeroPadList)
     214                 :     : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement)))
     215                 :     , mAxis(aAxis)
     216                 :     , mCanZeroPadList(aCanZeroPadList)
     217                 :   {}
     218                 : 
     219               0 :   void SetInfo(nsSVGElement *aElement, PRUint8 aAxis, bool aCanZeroPadList) {
     220               0 :     mElement = do_GetWeakReference(static_cast<nsINode*>(aElement));
     221               0 :     mAxis = aAxis;
     222               0 :     mCanZeroPadList = aCanZeroPadList;
     223               0 :   }
     224                 : 
     225               0 :   nsSVGElement* Element() const {
     226               0 :     nsCOMPtr<nsIContent> e = do_QueryReferent(mElement);
     227               0 :     return static_cast<nsSVGElement*>(e.get());
     228                 :   }
     229                 : 
     230               0 :   PRUint8 Axis() const {
     231               0 :     NS_ABORT_IF_FALSE(mElement, "Axis() isn't valid");
     232               0 :     return mAxis;
     233                 :   }
     234                 : 
     235                 :   /**
     236                 :    * The value returned by this function depends on which attribute this object
     237                 :    * is for. If appending a list of zeros to the attribute's list would have no
     238                 :    * affect on rendering (e.g. the attributes 'dx' and 'dy' on <text>), then
     239                 :    * this method will return true. If appending a list of zeros to the
     240                 :    * attribute's list could *change* rendering (e.g. the attributes 'x' and 'y'
     241                 :    * on <text>), then this method will return false.
     242                 :    *
     243                 :    * The reason that this method exists is because the SMIL code needs to know
     244                 :    * what to do when it's asked to animate between lists of different length.
     245                 :    * If this method returns true, then it can zero pad the short list before
     246                 :    * carrying out its operations. However, in the case of the 'x' and 'y'
     247                 :    * attributes on <text>, zero would mean "zero in the current coordinate
     248                 :    * system", whereas we would want to pad shorter lists with the coordinates
     249                 :    * at which glyphs would otherwise lie, which is almost certainly not zero!
     250                 :    * Animating from/to zeros in this case would produce terrible results.
     251                 :    *
     252                 :    * Currently SVGLengthListSMILType simply disallows (drops) animation between
     253                 :    * lists of different length if it can't zero pad a list. This is to avoid
     254                 :    * having some authors create content that depends on undesirable behaviour
     255                 :    * (which would make it difficult for us to fix the behavior in future). At
     256                 :    * some point it would be nice to implement a callback to allow this code to
     257                 :    * determine padding values for lists that can't be zero padded. See
     258                 :    * https://bugzilla.mozilla.org/show_bug.cgi?id=573431
     259                 :    */
     260               0 :   bool CanZeroPadList() const {
     261                 :     //NS_ASSERTION(mElement, "CanZeroPadList() isn't valid");
     262               0 :     return mCanZeroPadList;
     263                 :   }
     264                 : 
     265                 :   // For the SMIL code. See comment in SVGLengthListSMILType::Add().
     266               0 :   void SetCanZeroPadList(bool aCanZeroPadList) {
     267               0 :     mCanZeroPadList = aCanZeroPadList;
     268               0 :   }
     269                 : 
     270               0 :   nsresult CopyFrom(const SVGLengthListAndInfo& rhs) {
     271               0 :     mElement = rhs.mElement;
     272               0 :     mAxis = rhs.mAxis;
     273               0 :     mCanZeroPadList = rhs.mCanZeroPadList;
     274               0 :     return SVGLengthList::CopyFrom(rhs);
     275                 :   }
     276                 : 
     277                 :   // Instances of this special subclass do not have DOM wrappers that we need
     278                 :   // to worry about keeping in sync, so it's safe to expose any hidden base
     279                 :   // class methods required by the SMIL code, as we do below.
     280                 : 
     281                 :   /**
     282                 :    * Exposed so that SVGLengthList baseVals can be copied to
     283                 :    * SVGLengthListAndInfo objects. Note that callers should also call
     284                 :    * SetInfo() when using this method!
     285                 :    */
     286               0 :   nsresult CopyFrom(const SVGLengthList& rhs) {
     287               0 :     return SVGLengthList::CopyFrom(rhs);
     288                 :   }
     289               0 :   const SVGLength& operator[](PRUint32 aIndex) const {
     290               0 :     return SVGLengthList::operator[](aIndex);
     291                 :   }
     292               0 :   SVGLength& operator[](PRUint32 aIndex) {
     293               0 :     return SVGLengthList::operator[](aIndex);
     294                 :   }
     295               0 :   bool SetLength(PRUint32 aNumberOfItems) {
     296               0 :     return SVGLengthList::SetLength(aNumberOfItems);
     297                 :   }
     298                 : 
     299                 : private:
     300                 :   // We must keep a weak reference to our element because we may belong to a
     301                 :   // cached baseVal nsSMILValue. See the comments starting at:
     302                 :   // https://bugzilla.mozilla.org/show_bug.cgi?id=515116#c15
     303                 :   // See also https://bugzilla.mozilla.org/show_bug.cgi?id=653497
     304                 :   nsWeakPtr mElement;
     305                 :   PRUint8 mAxis;
     306                 :   bool mCanZeroPadList;
     307                 : };
     308                 : 
     309                 : 
     310                 : /**
     311                 :  * This class wraps SVGLengthList objects to allow frame consumers to process
     312                 :  * SVGLengthList objects as if they were simply a list of float values in user
     313                 :  * units. When consumers request the value at a given index, this class
     314                 :  * dynamically converts the corresponding SVGLength from its actual unit and
     315                 :  * returns its value in user units.
     316                 :  *
     317                 :  * Consumers should check that the user unit values returned are finite. Even
     318                 :  * if the consumer can guarantee the list's element has a valid viewport
     319                 :  * ancestor to resolve percentage units against, and a valid presContext and
     320                 :  * styleContext to resolve absolute and em/ex units against, unit conversions
     321                 :  * could still overflow. In that case the value returned will be
     322                 :  * numeric_limits<float>::quiet_NaN().
     323                 :  */
     324                 : class NS_STACK_CLASS SVGUserUnitList
     325                 : {
     326                 : public:
     327                 : 
     328               0 :   SVGUserUnitList()
     329               0 :     : mList(nsnull)
     330               0 :   {}
     331                 : 
     332               0 :   void Init(const SVGLengthList *aList, nsSVGElement *aElement, PRUint8 aAxis) {
     333               0 :     mList = aList;
     334               0 :     mElement = aElement;
     335               0 :     mAxis = aAxis;
     336               0 :   }
     337                 : 
     338               0 :   void Clear() {
     339               0 :     mList = nsnull;
     340               0 :   }
     341                 : 
     342               0 :   PRUint32 Length() const {
     343               0 :     return mList ? mList->Length() : 0;
     344                 :   }
     345                 : 
     346                 :   /// This may return a non-finite value
     347               0 :   float operator[](PRUint32 aIndex) const {
     348               0 :     return (*mList)[aIndex].GetValueInUserUnits(mElement, mAxis);
     349                 :   }
     350                 : 
     351                 : private:
     352                 :   const SVGLengthList *mList;
     353                 :   nsSVGElement *mElement;
     354                 :   PRUint8 mAxis;
     355                 : };
     356                 : 
     357                 : } // namespace mozilla
     358                 : 
     359                 : #endif // MOZILLA_SVGLENGTHLIST_H__

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