The Tor Browser: dom/smil/nsISMILType.h@97036ab72558 (annotated)

dom/smil/nsISMILType.h@97036ab72558 (annotated)

dom/smil/nsISMILType.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 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/. */
 #ifndef NS_ISMILTYPE_H_
 #define NS_ISMILTYPE_H_
 #include "mozilla/Attributes.h"
 #include "nscore.h"
 class nsSMILValue;
 //////////////////////////////////////////////////////////////////////////////
 // nsISMILType: Interface for defining the basic operations needed for animating
 // a particular kind of data (e.g. lengths, colors, transformation matrices).
 //
 // This interface is never used directly but always through an nsSMILValue that
 // bundles together a pointer to a concrete implementation of this interface and
 // the data upon which it should operate.
 //
 // We keep the data and type separate rather than just providing different
 // subclasses of nsSMILValue. This is so that sizeof(nsSMILValue) is the same
 // for all value types, allowing us to have a type-agnostic nsTArray of
 // nsSMILValue objects (actual objects, not pointers). It also allows most
 // nsSMILValues (except those that need to allocate extra memory for their
 // data) to be allocated on the stack and directly assigned to one another
 // provided performance benefits for the animation code.
 //
 // Note that different types have different capabilities. Roughly speaking there
 // are probably three main types:
 //
 // +---------------------+---------------+-------------+------------------+
 // | CATEGORY:           | DISCRETE      | LINEAR      | ADDITIVE         |
 // +---------------------+---------------+-------------+------------------+
 // | Example:            | strings,      | path data?  | lengths,         |
 // |                     | color k/words?|             | RGB color values |
 // |                     |               |             |                  |
 // | -- Assign?          |     X         |    X        |    X             |
 // | -- Add?             |     -         |    X?       |    X             |
 // | -- SandwichAdd?     |     -         |    -?       |    X             |
 // | -- ComputeDistance? |     -         |    -        |    X?            |
 // | -- Interpolate?     |     -         |    X        |    X             |
 // +---------------------+---------------+-------------+------------------+
 //
 class nsISMILType
 {
   /**
    * Only give the nsSMILValue class access to this interface.
    */
   friend class nsSMILValue;
 protected:
   /**
    * Initialises aValue and sets it to some identity value such that adding
    * aValue to another value of the same type has no effect.
    *
    * @pre  aValue.IsNull()
    * @post aValue.mType == this
    */
   virtual void Init(nsSMILValue& aValue) const = 0;
   /**
    * Destroys any data associated with a value of this type.
    *
    * @pre  aValue.mType == this
    * @post aValue.IsNull()
    */
   virtual void Destroy(nsSMILValue& aValue) const = 0;
   /**
    * Assign this object the value of another. Think of this as the assignment
    * operator.
    *
    * @param   aDest       The left-hand side of the assignment.
    * @param   aSrc        The right-hand side of the assignment.
    * @return  NS_OK on success, an error code on failure such as when the
    *          underlying type of the specified object differs.
    *
    * @pre aDest.mType == aSrc.mType == this
    */
   virtual nsresult Assign(nsSMILValue& aDest,
                           const nsSMILValue& aSrc) const = 0;
   /**
    * Test two nsSMILValue objects (of this nsISMILType) for equality.
    *
    * A return value of true represents a guarantee that aLeft and aRight are
    * equal. (That is, they would behave identically if passed to the methods
    * Add, SandwichAdd, ComputeDistance, and Interpolate).
    *
    * A return value of false simply indicates that we make no guarantee
    * about equality.
    *
    * NOTE: It's perfectly legal for implementations of this method to return
    * false in all cases.  However, smarter implementations will make this
    * method more useful for optimization.
    *
    * @param   aLeft       The left-hand side of the equality check.
    * @param   aRight      The right-hand side of the equality check.
    * @return  true if we're sure the values are equal, false otherwise.
    *
    * @pre aDest.mType == aSrc.mType == this
    */
   virtual bool IsEqual(const nsSMILValue& aLeft,
                          const nsSMILValue& aRight) const = 0;
   /**
    * Adds two values.
    *
    * The count parameter facilitates repetition.
    *
    * By equation,
    *
    *   aDest += aValueToAdd * aCount
    *
    * Therefore, if aCount == 0, aDest will be unaltered.
    *
    * This method will fail if this data type is not additive or the value was
    * not specified using an additive syntax.
    *
    * See SVG 1.1, section 19.2.5. In particular,
    *
    *   "If a given attribute or property can take values of keywords (which are
    *   not additive) or numeric values (which are additive), then additive
    *   animations are possible if the subsequent animation uses a numeric value
    *   even if the base animation uses a keyword value; however, if the
    *   subsequent animation uses a keyword value, additive animation is not
    *   possible."
    *
    * If this method fails (e.g. because the data type is not additive), aDest
    * will be unaltered.
    *
    * @param   aDest       The value to add to.
    * @param   aValueToAdd The value to add.
    * @param   aCount      The number of times to add aValueToAdd.
    * @return  NS_OK on success, an error code on failure.
    *
    * @pre aValueToAdd.mType == aDest.mType == this
    */
   virtual nsresult Add(nsSMILValue& aDest,
                        const nsSMILValue& aValueToAdd,
                        uint32_t aCount) const = 0;
   /**
    * Adds aValueToAdd to the underlying value in the animation sandwich, aDest.
    *
    * For most types this operation is identical to a regular Add() but for some
    * types (notably <animateTransform>) the operation differs. For
    * <animateTransform> Add() corresponds to simply adding together the
    * transform parameters and is used when calculating cumulative values or
    * by-animation values. On the other hand SandwichAdd() is used when adding to
    * the underlying value and requires matrix post-multiplication. (This
    * distinction is most clearly indicated by the SVGT1.2 test suite. It is not
    * obvious within the SMIL specifications.)
    *
    * @param   aDest       The value to add to.
    * @param   aValueToAdd The value to add.
    * @return  NS_OK on success, an error code on failure.
    *
    * @pre aValueToAdd.mType == aDest.mType == this
    */
   virtual nsresult SandwichAdd(nsSMILValue& aDest,
                                const nsSMILValue& aValueToAdd) const
   {
     return Add(aDest, aValueToAdd, 1);
   }
   /**
    * Calculates the 'distance' between two values. This is the distance used in
    * paced interpolation.
    *
    * @param   aFrom     The start of the interval for which the distance should
    *                    be calculated.
    * @param   aTo       The end of the interval for which the distance should be
    *                    calculated.
    * @param   aDistance The result of the calculation.
    * @return  NS_OK on success, or an appropriate error code if there is no
    *          notion of distance for the underlying data type or the distance
    *          could not be calculated.
    *
    * @pre aFrom.mType == aTo.mType == this
    */
   virtual nsresult ComputeDistance(const nsSMILValue& aFrom,
                                    const nsSMILValue& aTo,
                                    double& aDistance) const = 0;
   /**
    * Calculates an interpolated value between two values using the specified
    * proportion.
    *
    * @param   aStartVal     The value defining the start of the interval of
    *                        interpolation.
    * @param   aEndVal       The value defining the end of the interval of
    *                        interpolation.
    * @param   aUnitDistance A number between 0.0 and 1.0 (inclusive) defining
    *                        the distance of the interpolated value in the
    *                        interval.
    * @param   aResult       The interpolated value.
    * @return  NS_OK on success, NS_ERROR_FAILURE if this data type cannot be
    *          interpolated or NS_ERROR_OUT_OF_MEMORY if insufficient memory was
    *          available for storing the result.
    *
    * @pre aStartVal.mType == aEndVal.mType == aResult.mType == this
    */
   virtual nsresult Interpolate(const nsSMILValue& aStartVal,
                                const nsSMILValue& aEndVal,
                                double aUnitDistance,
                                nsSMILValue& aResult) const = 0;
 };
 #endif // NS_ISMILTYPE_H_

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dom/smil/nsISMILType.h@97036ab72558 (annotated)

dom/smil/nsISMILType.h