diff options
Diffstat (limited to 'dom/svg/SVGLengthListSMILType.h')
-rw-r--r-- | dom/svg/SVGLengthListSMILType.h | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/dom/svg/SVGLengthListSMILType.h b/dom/svg/SVGLengthListSMILType.h new file mode 100644 index 000000000..10321b585 --- /dev/null +++ b/dom/svg/SVGLengthListSMILType.h @@ -0,0 +1,101 @@ +/* -*- 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 MOZILLA_SVGLENGTHLISTSMILTYPE_H_ +#define MOZILLA_SVGLENGTHLISTSMILTYPE_H_ + +#include "mozilla/Attributes.h" +#include "nsISMILType.h" + +class nsSMILValue; + +namespace mozilla { + +//////////////////////////////////////////////////////////////////////// +// SVGLengthListSMILType +// +// Operations for animating an SVGLengthList. +// +class SVGLengthListSMILType : public nsISMILType +{ +public: + // Singleton for nsSMILValue objects to hold onto. + static SVGLengthListSMILType sSingleton; + +protected: + // nsISMILType Methods + // ------------------- + + /** + * When this method initializes the SVGLengthListAndInfo for its nsSMILValue + * argument, it has to blindly set its mCanZeroPadList to true despite + * the fact that some attributes can't be zero-padded. (See the explaination + * that follows.) SVGAnimatedLengthList::SMILAnimatedLengthList's + * GetBaseValue() and ValueFromString() methods then override this for the + * nsSMILValue objects that they create to set this flag to the appropriate + * value for the attribute in question. + * + * The reason that we default to setting the mCanZeroPadList to true is + * because the SMIL engine creates "zero" valued nsSMILValue objects for + * intermediary calculations, and may pass such an nsSMILValue (along with an + * nsSMILValue from an animation element - that is an nsSMILValue created by + * SVGAnimatedLengthList::SMILAnimatedLengthList's GetBaseValue() or + * ValueFromString() methods) into the Add(), ComputeDistance() or + * Interpolate() methods below. Even in the case of animation of list + * attributes that may *not* be padded with zeros (such as 'x' and 'y' on the + * <text> element), we need to allow zero-padding of these "zero" valued + * nsSMILValue's lists. One reason for this is illustrated by the following + * example: + * + * <text x="2 4">foo + * <animate by="2 2" .../> + * </text> + * + * In this example there are two SMIL animation layers to be sandwiched: the + * base layer, and the layer created for the <animate> element. The SMIL + * engine calculates the result of each layer *independently*, before + * compositing the results together. Thus for the <animate> sandwich layer + * the SMIL engine interpolates between a "zero" nsSMILValue that it creates + * (since there is no explicit "from") and the "2 2", before the result of + * that interpolation is added to the "2 4" from the base layer. Clearly for + * the interpolation between the "zero" nsSMILValue and "2 2" to work, the + * "zero" nsSMILValue's SVGLengthListAndInfo must be zero paddable - hence + * why this method always sets mCanZeroPadList to true. + * + * (Since the Add(), ComputeDistance() and Interpolate() methods may be + * passed two input nsSMILValue objects for which CanZeroPadList() returns + * opposite values, these methods must be careful what they set the flag to + * on the nsSMILValue that they output. If *either* of the input nsSMILValues + * has an SVGLengthListAndInfo for which CanZeroPadList() returns false, + * then they must set the flag to false on the output nsSMILValue too. If + * the methods failed to do that, then when the result nsSMILValue objects + * from each sandwich layer are composited together, we could end up allowing + * animation between lists of different length when we should not!) + */ + virtual void Init(nsSMILValue& aValue) const override; + + virtual void Destroy(nsSMILValue& aValue) const override; + virtual nsresult Assign(nsSMILValue& aDest, const nsSMILValue& aSrc) const override; + virtual bool IsEqual(const nsSMILValue& aLeft, + const nsSMILValue& aRight) const override; + virtual nsresult Add(nsSMILValue& aDest, const nsSMILValue& aValueToAdd, + uint32_t aCount) const override; + virtual nsresult ComputeDistance(const nsSMILValue& aFrom, + const nsSMILValue& aTo, + double& aDistance) const override; + virtual nsresult Interpolate(const nsSMILValue& aStartVal, + const nsSMILValue& aEndVal, + double aUnitDistance, + nsSMILValue& aResult) const override; + +private: + // Private constructor: prevent instances beyond my singleton. + constexpr SVGLengthListSMILType() {} +}; + +} // namespace mozilla + +#endif // MOZILLA_SVGLENGTHLISTSMILTYPE_H_ |