SVGMatrix.h (5130B)
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ 3 /* This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 /** 8 * Notes on transforms in Mozilla and the SVG code. 9 * 10 * It's important to note that the matrix convention used in the SVG standard 11 * is the opposite convention to the one used in the Mozilla code or, more 12 * specifically, the convention used in Thebes code (code using gfxMatrix). 13 * Whereas the SVG standard uses the column vector convention, Thebes code uses 14 * the row vector convention. Thus, whereas in the SVG standard you have 15 * [M1][M2][M3]|p|, in Thebes you have |p|'[M3]'[M2]'[M1]'. In other words, the 16 * following are equivalent: 17 * 18 * / a1 c1 tx1 \ / a2 c2 tx2 \ / a3 c3 tx3 \ / x \ 19 * SVG: | b1 d1 ty1 | | b2 d2 ty2 | | b3 d3 ty3 | | y | 20 * \ 0 0 1 / \ 0 0 1 / \ 0 0 1 / \ 1 / 21 * 22 * / a3 b3 0 \ / a2 b2 0 \ / a1 b1 0 \ 23 * Thebes: [ x y 1 ] | c3 d3 0 | | c2 d2 0 | | c1 d1 0 | 24 * \ tx3 ty3 1 / \ tx2 ty2 1 / \ tx1 ty1 1 / 25 * 26 * Because the Thebes representation of a transform is the transpose of the SVG 27 * representation, our transform order must be reversed when representing SVG 28 * transforms using gfxMatrix in the SVG code. Since the SVG implementation 29 * stores and obtains matrices in SVG order, to do this we must pre-multiply 30 * gfxMatrix objects that represent SVG transforms instead of post-multiplying 31 * them as we would for matrices using SVG's column vector convention. 32 * Pre-multiplying may look wrong if you're only familiar with the SVG 33 * convention, but in that case hopefully the above explanation clears things 34 * up. 35 */ 36 37 #ifndef DOM_SVG_SVGMATRIX_H_ 38 #define DOM_SVG_SVGMATRIX_H_ 39 40 #include "DOMSVGTransform.h" 41 #include "gfxMatrix.h" 42 #include "nsCycleCollectionParticipant.h" 43 #include "nsWrapperCache.h" 44 45 namespace mozilla::dom { 46 47 struct DOMMatrix2DInit; 48 49 /** 50 * DOM wrapper for an SVG matrix. 51 */ 52 class SVGMatrix final : public nsWrapperCache { 53 public: 54 NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(SVGMatrix) 55 NS_DECL_CYCLE_COLLECTION_NATIVE_WRAPPERCACHE_CLASS(SVGMatrix) 56 57 /** 58 * Ctor for SVGMatrix objects that belong to a DOMSVGTransform. 59 */ 60 explicit SVGMatrix(DOMSVGTransform& aTransform) : mTransform(&aTransform) {} 61 62 /** 63 * Ctors for SVGMatrix objects created independently of a DOMSVGTransform. 64 */ 65 // Default ctor for gfxMatrix will produce identity mx 66 SVGMatrix() = default; 67 68 explicit SVGMatrix(const gfxMatrix& aMatrix) : mMatrix(aMatrix) {} 69 70 // WebIDL 71 DOMSVGTransform* GetParentObject() const; 72 JSObject* WrapObject(JSContext* aCx, 73 JS::Handle<JSObject*> aGivenProto) override; 74 75 float A() const { return static_cast<float>(GetMatrix()._11); } 76 void SetA(float aA, ErrorResult& aRv); 77 float B() const { return static_cast<float>(GetMatrix()._12); } 78 void SetB(float aB, ErrorResult& aRv); 79 float C() const { return static_cast<float>(GetMatrix()._21); } 80 void SetC(float aC, ErrorResult& aRv); 81 float D() const { return static_cast<float>(GetMatrix()._22); } 82 void SetD(float aD, ErrorResult& aRv); 83 float E() const { return static_cast<float>(GetMatrix()._31); } 84 void SetE(float aE, ErrorResult& aRv); 85 float F() const { return static_cast<float>(GetMatrix()._32); } 86 void SetF(float aF, ErrorResult& aRv); 87 already_AddRefed<SVGMatrix> Multiply(const DOMMatrix2DInit& aMatrix, 88 ErrorResult& aRv); 89 already_AddRefed<SVGMatrix> Inverse(ErrorResult& aRv); 90 already_AddRefed<SVGMatrix> Translate(float x, float y); 91 already_AddRefed<SVGMatrix> Scale(float scaleFactor); 92 already_AddRefed<SVGMatrix> ScaleNonUniform(float scaleFactorX, 93 float scaleFactorY); 94 already_AddRefed<SVGMatrix> Rotate(float angle); 95 already_AddRefed<SVGMatrix> RotateFromVector(float x, float y, 96 ErrorResult& aRv); 97 already_AddRefed<SVGMatrix> FlipX(); 98 already_AddRefed<SVGMatrix> FlipY(); 99 already_AddRefed<SVGMatrix> SkewX(float angle, ErrorResult& aRv); 100 already_AddRefed<SVGMatrix> SkewY(float angle, ErrorResult& aRv); 101 102 private: 103 ~SVGMatrix() = default; 104 105 const gfxMatrix& GetMatrix() const { 106 return mTransform ? mTransform->Matrixgfx() : mMatrix; 107 } 108 109 void SetMatrix(const gfxMatrix& aMatrix) { 110 if (mTransform) { 111 mTransform->SetMatrix(aMatrix); 112 } else { 113 mMatrix = aMatrix; 114 } 115 } 116 117 bool IsAnimVal() const { 118 return mTransform ? mTransform->IsAnimVal() : false; 119 } 120 121 RefPtr<DOMSVGTransform> mTransform; 122 123 // Typically we operate on the matrix data accessed via mTransform but for 124 // matrices that exist independently of an DOMSVGTransform we use mMatrix 125 // below. 126 gfxMatrix mMatrix; 127 }; 128 129 } // namespace mozilla::dom 130 131 #endif // DOM_SVG_SVGMATRIX_H_