1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkPathEffect_DEFINED 11 #define SkPathEffect_DEFINED 12 13 #include "SkFlattenable.h" 14 #include "SkPath.h" 15 #include "SkPoint.h" 16 #include "SkRect.h" 17 #include "SkStrokeRec.h" 18 #include "SkTDArray.h" 19 20 class SkPath; 21 22 /** \class SkPathEffect 23 24 SkPathEffect is the base class for objects in the SkPaint that affect 25 the geometry of a drawing primitive before it is transformed by the 26 canvas' matrix and drawn. 27 28 Dashing is implemented as a subclass of SkPathEffect. 29 */ 30 class SK_API SkPathEffect : public SkFlattenable { 31 public: 32 SK_DECLARE_INST_COUNT(SkPathEffect) 33 34 SkPathEffect() {} 35 36 /** 37 * Given a src path (input) and a stroke-rec (input and output), apply 38 * this effect to the src path, returning the new path in dst, and return 39 * true. If this effect cannot be applied, return false and ignore dst 40 * and stroke-rec. 41 * 42 * The stroke-rec specifies the initial request for stroking (if any). 43 * The effect can treat this as input only, or it can choose to change 44 * the rec as well. For example, the effect can decide to change the 45 * stroke's width or join, or the effect can change the rec from stroke 46 * to fill (or fill to stroke) in addition to returning a new (dst) path. 47 * 48 * If this method returns true, the caller will apply (as needed) the 49 * resulting stroke-rec to dst and then draw. 50 */ 51 virtual bool filterPath(SkPath* dst, const SkPath& src, 52 SkStrokeRec*, const SkRect* cullR) const = 0; 53 54 /** 55 * Compute a conservative bounds for its effect, given the src bounds. 56 * The baseline implementation just assigns src to dst. 57 */ 58 virtual void computeFastBounds(SkRect* dst, const SkRect& src) const; 59 60 /** \class PointData 61 62 PointData aggregates all the information needed to draw the point 63 primitives returned by an 'asPoints' call. 64 */ 65 class PointData { 66 public: 67 PointData() 68 : fFlags(0) 69 , fPoints(NULL) 70 , fNumPoints(0) { 71 fSize.set(SK_Scalar1, SK_Scalar1); 72 // 'asPoints' needs to initialize/fill-in 'fClipRect' if it sets 73 // the kUseClip flag 74 }; 75 ~PointData() { 76 delete [] fPoints; 77 } 78 79 // TODO: consider using passed-in flags to limit the work asPoints does. 80 // For example, a kNoPath flag could indicate don't bother generating 81 // stamped solutions. 82 83 // Currently none of these flags are supported. 84 enum PointFlags { 85 kCircles_PointFlag = 0x01, // draw points as circles (instead of rects) 86 kUsePath_PointFlag = 0x02, // draw points as stamps of the returned path 87 kUseClip_PointFlag = 0x04, // apply 'fClipRect' before drawing the points 88 }; 89 90 uint32_t fFlags; // flags that impact the drawing of the points 91 SkPoint* fPoints; // the center point of each generated point 92 int fNumPoints; // number of points in fPoints 93 SkVector fSize; // the size to draw the points 94 SkRect fClipRect; // clip required to draw the points (if kUseClip is set) 95 SkPath fPath; // 'stamp' to be used at each point (if kUsePath is set) 96 97 SkPath fFirst; // If not empty, contains geometry for first point 98 SkPath fLast; // If not empty, contains geometry for last point 99 }; 100 101 /** 102 * Does applying this path effect to 'src' yield a set of points? If so, 103 * optionally return the points in 'results'. 104 */ 105 virtual bool asPoints(PointData* results, const SkPath& src, 106 const SkStrokeRec&, const SkMatrix&, 107 const SkRect* cullR) const; 108 109 SK_DEFINE_FLATTENABLE_TYPE(SkPathEffect) 110 111 protected: 112 SkPathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {} 113 114 private: 115 // illegal 116 SkPathEffect(const SkPathEffect&); 117 SkPathEffect& operator=(const SkPathEffect&); 118 119 typedef SkFlattenable INHERITED; 120 }; 121 122 /** \class SkPairPathEffect 123 124 Common baseclass for Compose and Sum. This subclass manages two pathEffects, 125 including flattening them. It does nothing in filterPath, and is only useful 126 for managing the lifetimes of its two arguments. 127 */ 128 class SkPairPathEffect : public SkPathEffect { 129 public: 130 SkPairPathEffect(SkPathEffect* pe0, SkPathEffect* pe1); 131 virtual ~SkPairPathEffect(); 132 133 protected: 134 SkPairPathEffect(SkFlattenableReadBuffer&); 135 virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE; 136 137 // these are visible to our subclasses 138 SkPathEffect* fPE0, *fPE1; 139 140 private: 141 typedef SkPathEffect INHERITED; 142 }; 143 144 /** \class SkComposePathEffect 145 146 This subclass of SkPathEffect composes its two arguments, to create 147 a compound pathEffect. 148 */ 149 class SkComposePathEffect : public SkPairPathEffect { 150 public: 151 /** Construct a pathEffect whose effect is to apply first the inner pathEffect 152 and the the outer pathEffect (e.g. outer(inner(path))) 153 The reference counts for outer and inner are both incremented in the constructor, 154 and decremented in the destructor. 155 */ 156 SkComposePathEffect(SkPathEffect* outer, SkPathEffect* inner) 157 : INHERITED(outer, inner) {} 158 159 virtual bool filterPath(SkPath* dst, const SkPath& src, 160 SkStrokeRec*, const SkRect*) const SK_OVERRIDE; 161 162 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposePathEffect) 163 164 protected: 165 SkComposePathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {} 166 167 private: 168 // illegal 169 SkComposePathEffect(const SkComposePathEffect&); 170 SkComposePathEffect& operator=(const SkComposePathEffect&); 171 172 typedef SkPairPathEffect INHERITED; 173 }; 174 175 /** \class SkSumPathEffect 176 177 This subclass of SkPathEffect applies two pathEffects, one after the other. 178 Its filterPath() returns true if either of the effects succeeded. 179 */ 180 class SkSumPathEffect : public SkPairPathEffect { 181 public: 182 /** Construct a pathEffect whose effect is to apply two effects, in sequence. 183 (e.g. first(path) + second(path)) 184 The reference counts for first and second are both incremented in the constructor, 185 and decremented in the destructor. 186 */ 187 SkSumPathEffect(SkPathEffect* first, SkPathEffect* second) 188 : INHERITED(first, second) {} 189 190 virtual bool filterPath(SkPath* dst, const SkPath& src, 191 SkStrokeRec*, const SkRect*) const SK_OVERRIDE; 192 193 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSumPathEffect) 194 195 protected: 196 SkSumPathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {} 197 198 private: 199 // illegal 200 SkSumPathEffect(const SkSumPathEffect&); 201 SkSumPathEffect& operator=(const SkSumPathEffect&); 202 203 typedef SkPairPathEffect INHERITED; 204 }; 205 206 #endif 207
