/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* 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 DOM_SMIL_SMILTYPE_H_ #define DOM_SMIL_SMILTYPE_H_ #include "mozilla/Attributes.h" #include "nscore.h" namespace mozilla { class SMILValue; ////////////////////////////////////////////////////////////////////////////// // SMILType: 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 a SMILValue 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 SMILValue. This is so that sizeof(SMILValue) is the same // for all value types, allowing us to have a type-agnostic nsTArray of // SMILValue objects (actual objects, not pointers). It also allows most // SMILValues (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 SMILType { /** * Only give the SMILValue class access to this interface. */ friend class SMILValue; 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(SMILValue& aValue) const = 0; /** * Destroys any data associated with a value of this type. * * @pre aValue.mType == this * @post aValue.IsNull() */ virtual void Destroy(SMILValue& 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(SMILValue& aDest, const SMILValue& aSrc) const = 0; /** * Test two SMILValue objects (of this SMILType) 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 SMILValue& aLeft, const SMILValue& 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(SMILValue& aDest, const SMILValue& 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 ) the operation differs. For * 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(SMILValue& aDest, const SMILValue& 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 SMILValue& aFrom, const SMILValue& 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 SMILValue& aStartVal, const SMILValue& aEndVal, double aUnitDistance, SMILValue& aResult) const = 0; }; } // namespace mozilla #endif // DOM_SMIL_SMILTYPE_H_