1 /* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkPathEffect_DEFINED 9 #define SkPathEffect_DEFINED 10 11 #include "SkFlattenable.h" 12 #include "SkPath.h" 13 #include "SkPoint.h" 14 #include "SkRect.h" 15 16 class SkPath; 17 class SkStrokeRec; 18 19 /** \class SkPathEffect 20 21 SkPathEffect is the base class for objects in the SkPaint that affect 22 the geometry of a drawing primitive before it is transformed by the 23 canvas' matrix and drawn. 24 25 Dashing is implemented as a subclass of SkPathEffect. 26 */ 27 class SK_API SkPathEffect : public SkFlattenable { 28 public: 29 /** 30 * Returns a patheffect that apples each effect (first and second) to the original path, 31 * and returns a path with the sum of these. 32 * 33 * result = first(path) + second(path) 34 * 35 */ 36 static sk_sp<SkPathEffect> MakeSum(sk_sp<SkPathEffect> first, sk_sp<SkPathEffect> second); 37 38 /** 39 * Returns a patheffect that applies the inner effect to the path, and then applies the 40 * outer effect to the result of the inner's. 41 * 42 * result = outer(inner(path)) 43 */ 44 static sk_sp<SkPathEffect> MakeCompose(sk_sp<SkPathEffect> outer, sk_sp<SkPathEffect> inner); 45 46 /** 47 * Given a src path (input) and a stroke-rec (input and output), apply 48 * this effect to the src path, returning the new path in dst, and return 49 * true. If this effect cannot be applied, return false and ignore dst 50 * and stroke-rec. 51 * 52 * The stroke-rec specifies the initial request for stroking (if any). 53 * The effect can treat this as input only, or it can choose to change 54 * the rec as well. For example, the effect can decide to change the 55 * stroke's width or join, or the effect can change the rec from stroke 56 * to fill (or fill to stroke) in addition to returning a new (dst) path. 57 * 58 * If this method returns true, the caller will apply (as needed) the 59 * resulting stroke-rec to dst and then draw. 60 */ 61 virtual bool filterPath(SkPath* dst, const SkPath& src, 62 SkStrokeRec*, const SkRect* cullR) const = 0; 63 64 /** 65 * Compute a conservative bounds for its effect, given the src bounds. 66 * The baseline implementation just assigns src to dst. 67 */ 68 virtual void computeFastBounds(SkRect* dst, const SkRect& src) const; 69 70 /** \class PointData 71 72 PointData aggregates all the information needed to draw the point 73 primitives returned by an 'asPoints' call. 74 */ 75 class PointData { 76 public: 77 PointData() 78 : fFlags(0) 79 , fPoints(nullptr) 80 , fNumPoints(0) { 81 fSize.set(SK_Scalar1, SK_Scalar1); 82 // 'asPoints' needs to initialize/fill-in 'fClipRect' if it sets 83 // the kUseClip flag 84 } 85 ~PointData() { 86 delete [] fPoints; 87 } 88 89 // TODO: consider using passed-in flags to limit the work asPoints does. 90 // For example, a kNoPath flag could indicate don't bother generating 91 // stamped solutions. 92 93 // Currently none of these flags are supported. 94 enum PointFlags { 95 kCircles_PointFlag = 0x01, // draw points as circles (instead of rects) 96 kUsePath_PointFlag = 0x02, // draw points as stamps of the returned path 97 kUseClip_PointFlag = 0x04, // apply 'fClipRect' before drawing the points 98 }; 99 100 uint32_t fFlags; // flags that impact the drawing of the points 101 SkPoint* fPoints; // the center point of each generated point 102 int fNumPoints; // number of points in fPoints 103 SkVector fSize; // the size to draw the points 104 SkRect fClipRect; // clip required to draw the points (if kUseClip is set) 105 SkPath fPath; // 'stamp' to be used at each point (if kUsePath is set) 106 107 SkPath fFirst; // If not empty, contains geometry for first point 108 SkPath fLast; // If not empty, contains geometry for last point 109 }; 110 111 /** 112 * Does applying this path effect to 'src' yield a set of points? If so, 113 * optionally return the points in 'results'. 114 */ 115 virtual bool asPoints(PointData* results, const SkPath& src, 116 const SkStrokeRec&, const SkMatrix&, 117 const SkRect* cullR) const; 118 119 /** 120 * If the PathEffect can be represented as a dash pattern, asADash will return kDash_DashType 121 * and None otherwise. If a non NULL info is passed in, the various DashInfo will be filled 122 * in if the PathEffect can be a dash pattern. If passed in info has an fCount equal or 123 * greater to that of the effect, it will memcpy the values of the dash intervals into the 124 * info. Thus the general approach will be call asADash once with default info to get DashType 125 * and fCount. If effect can be represented as a dash pattern, allocate space for the intervals 126 * in info, then call asADash again with the same info and the intervals will get copied in. 127 */ 128 129 enum DashType { 130 kNone_DashType, //!< ignores the info parameter 131 kDash_DashType, //!< fills in all of the info parameter 132 }; 133 134 struct DashInfo { 135 DashInfo() : fIntervals(nullptr), fCount(0), fPhase(0) {} 136 DashInfo(SkScalar* intervals, int32_t count, SkScalar phase) 137 : fIntervals(intervals), fCount(count), fPhase(phase) {} 138 139 SkScalar* fIntervals; //!< Length of on/off intervals for dashed lines 140 // Even values represent ons, and odds offs 141 int32_t fCount; //!< Number of intervals in the dash. Should be even number 142 SkScalar fPhase; //!< Offset into the dashed interval pattern 143 // mod the sum of all intervals 144 }; 145 146 virtual DashType asADash(DashInfo* info) const; 147 148 SK_TO_STRING_PUREVIRT() 149 SK_DEFINE_FLATTENABLE_TYPE(SkPathEffect) 150 151 #ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK 152 /// Override for subclasses as appropriate. 153 virtual bool exposedInAndroidJavaAPI() const { return false; } 154 #endif 155 156 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 157 158 protected: 159 SkPathEffect() {} 160 161 private: 162 // illegal 163 SkPathEffect(const SkPathEffect&); 164 SkPathEffect& operator=(const SkPathEffect&); 165 166 typedef SkFlattenable INHERITED; 167 }; 168 169 #endif 170
