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 /** 35 * Given a src path (input) and a stroke-rec (input and output), apply 36 * this effect to the src path, returning the new path in dst, and return 37 * true. If this effect cannot be applied, return false and ignore dst 38 * and stroke-rec. 39 * 40 * The stroke-rec specifies the initial request for stroking (if any). 41 * The effect can treat this as input only, or it can choose to change 42 * the rec as well. For example, the effect can decide to change the 43 * stroke's width or join, or the effect can change the rec from stroke 44 * to fill (or fill to stroke) in addition to returning a new (dst) path. 45 * 46 * If this method returns true, the caller will apply (as needed) the 47 * resulting stroke-rec to dst and then draw. 48 */ 49 virtual bool filterPath(SkPath* dst, const SkPath& src, 50 SkStrokeRec*, const SkRect* cullR) const = 0; 51 52 /** 53 * Compute a conservative bounds for its effect, given the src bounds. 54 * The baseline implementation just assigns src to dst. 55 */ 56 virtual void computeFastBounds(SkRect* dst, const SkRect& src) const; 57 58 /** \class PointData 59 60 PointData aggregates all the information needed to draw the point 61 primitives returned by an 'asPoints' call. 62 */ 63 class PointData { 64 public: 65 PointData() 66 : fFlags(0) 67 , fPoints(NULL) 68 , fNumPoints(0) { 69 fSize.set(SK_Scalar1, SK_Scalar1); 70 // 'asPoints' needs to initialize/fill-in 'fClipRect' if it sets 71 // the kUseClip flag 72 }; 73 ~PointData() { 74 delete [] fPoints; 75 } 76 77 // TODO: consider using passed-in flags to limit the work asPoints does. 78 // For example, a kNoPath flag could indicate don't bother generating 79 // stamped solutions. 80 81 // Currently none of these flags are supported. 82 enum PointFlags { 83 kCircles_PointFlag = 0x01, // draw points as circles (instead of rects) 84 kUsePath_PointFlag = 0x02, // draw points as stamps of the returned path 85 kUseClip_PointFlag = 0x04, // apply 'fClipRect' before drawing the points 86 }; 87 88 uint32_t fFlags; // flags that impact the drawing of the points 89 SkPoint* fPoints; // the center point of each generated point 90 int fNumPoints; // number of points in fPoints 91 SkVector fSize; // the size to draw the points 92 SkRect fClipRect; // clip required to draw the points (if kUseClip is set) 93 SkPath fPath; // 'stamp' to be used at each point (if kUsePath is set) 94 95 SkPath fFirst; // If not empty, contains geometry for first point 96 SkPath fLast; // If not empty, contains geometry for last point 97 }; 98 99 /** 100 * Does applying this path effect to 'src' yield a set of points? If so, 101 * optionally return the points in 'results'. 102 */ 103 virtual bool asPoints(PointData* results, const SkPath& src, 104 const SkStrokeRec&, const SkMatrix&, 105 const SkRect* cullR) const; 106 107 /** 108 * If the PathEffect can be represented as a dash pattern, asADash will return kDash_DashType 109 * and None otherwise. If a non NULL info is passed in, the various DashInfo will be filled 110 * in if the PathEffect can be a dash pattern. If passed in info has an fCount equal or 111 * greater to that of the effect, it will memcpy the values of the dash intervals into the 112 * info. Thus the general approach will be call asADash once with default info to get DashType 113 * and fCount. If effect can be represented as a dash pattern, allocate space for the intervals 114 * in info, then call asADash again with the same info and the intervals will get copied in. 115 */ 116 117 enum DashType { 118 kNone_DashType, //!< ignores the info parameter 119 kDash_DashType, //!< fills in all of the info parameter 120 }; 121 122 struct DashInfo { 123 DashInfo() : fIntervals(NULL), fCount(0), fPhase(0) {} 124 125 SkScalar* fIntervals; //!< Length of on/off intervals for dashed lines 126 // Even values represent ons, and odds offs 127 int32_t fCount; //!< Number of intervals in the dash. Should be even number 128 SkScalar fPhase; //!< Offset into the dashed interval pattern 129 // mod the sum of all intervals 130 }; 131 132 virtual DashType asADash(DashInfo* info) const; 133 134 SK_DEFINE_FLATTENABLE_TYPE(SkPathEffect) 135 136 protected: 137 SkPathEffect() {} 138 SkPathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {} 139 140 private: 141 // illegal 142 SkPathEffect(const SkPathEffect&); 143 SkPathEffect& operator=(const SkPathEffect&); 144 145 typedef SkFlattenable INHERITED; 146 }; 147 148 /** \class SkPairPathEffect 149 150 Common baseclass for Compose and Sum. This subclass manages two pathEffects, 151 including flattening them. It does nothing in filterPath, and is only useful 152 for managing the lifetimes of its two arguments. 153 */ 154 class SkPairPathEffect : public SkPathEffect { 155 public: 156 virtual ~SkPairPathEffect(); 157 158 protected: 159 SkPairPathEffect(SkPathEffect* pe0, SkPathEffect* pe1); 160 SkPairPathEffect(SkReadBuffer&); 161 virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE; 162 163 // these are visible to our subclasses 164 SkPathEffect* fPE0, *fPE1; 165 166 private: 167 typedef SkPathEffect INHERITED; 168 }; 169 170 /** \class SkComposePathEffect 171 172 This subclass of SkPathEffect composes its two arguments, to create 173 a compound pathEffect. 174 */ 175 class SkComposePathEffect : public SkPairPathEffect { 176 public: 177 /** Construct a pathEffect whose effect is to apply first the inner pathEffect 178 and the the outer pathEffect (e.g. outer(inner(path))) 179 The reference counts for outer and inner are both incremented in the constructor, 180 and decremented in the destructor. 181 */ 182 static SkComposePathEffect* Create(SkPathEffect* outer, SkPathEffect* inner) { 183 return SkNEW_ARGS(SkComposePathEffect, (outer, inner)); 184 } 185 186 virtual bool filterPath(SkPath* dst, const SkPath& src, 187 SkStrokeRec*, const SkRect*) const SK_OVERRIDE; 188 189 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposePathEffect) 190 191 protected: 192 SkComposePathEffect(SkPathEffect* outer, SkPathEffect* inner) 193 : INHERITED(outer, inner) {} 194 explicit SkComposePathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {} 195 196 private: 197 // illegal 198 SkComposePathEffect(const SkComposePathEffect&); 199 SkComposePathEffect& operator=(const SkComposePathEffect&); 200 201 typedef SkPairPathEffect INHERITED; 202 }; 203 204 /** \class SkSumPathEffect 205 206 This subclass of SkPathEffect applies two pathEffects, one after the other. 207 Its filterPath() returns true if either of the effects succeeded. 208 */ 209 class SkSumPathEffect : public SkPairPathEffect { 210 public: 211 /** Construct a pathEffect whose effect is to apply two effects, in sequence. 212 (e.g. first(path) + second(path)) 213 The reference counts for first and second are both incremented in the constructor, 214 and decremented in the destructor. 215 */ 216 static SkSumPathEffect* Create(SkPathEffect* first, SkPathEffect* second) { 217 return SkNEW_ARGS(SkSumPathEffect, (first, second)); 218 } 219 220 virtual bool filterPath(SkPath* dst, const SkPath& src, 221 SkStrokeRec*, const SkRect*) const SK_OVERRIDE; 222 223 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSumPathEffect) 224 225 protected: 226 SkSumPathEffect(SkPathEffect* first, SkPathEffect* second) 227 : INHERITED(first, second) {} 228 explicit SkSumPathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {} 229 230 private: 231 // illegal 232 SkSumPathEffect(const SkSumPathEffect&); 233 SkSumPathEffect& operator=(const SkSumPathEffect&); 234 235 typedef SkPairPathEffect INHERITED; 236 }; 237 238 #endif 239
