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comparison: gfx/skia/trunk/include/core/SkPathRef.h

gfx/skia/trunk/include/core/SkPathRef.h

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1
2 /*
3 * Copyright 2012 Google Inc.
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 #ifndef SkPathRef_DEFINED
10 #define SkPathRef_DEFINED
11
12 #include "SkMatrix.h"
13 #include "SkPoint.h"
14 #include "SkRect.h"
15 #include "SkRefCnt.h"
16 #include "SkTDArray.h"
17 #include <stddef.h> // ptrdiff_t
18
19 class SkRBuffer;
20 class SkWBuffer;
21
22 /**
23 * Holds the path verbs and points. It is versioned by a generation ID. None of its public methods
24 * modify the contents. To modify or append to the verbs/points wrap the SkPathRef in an
25 * SkPathRef::Editor object. Installing the editor resets the generation ID. It also performs
26 * copy-on-write if the SkPathRef is shared by multiple SkPaths. The caller passes the Editor's
27 * constructor a SkAutoTUnref, which may be updated to point to a new SkPathRef after the editor's
28 * constructor returns.
29 *
30 * The points and verbs are stored in a single allocation. The points are at the begining of the
31 * allocation while the verbs are stored at end of the allocation, in reverse order. Thus the points
32 * and verbs both grow into the middle of the allocation until the meet. To access verb i in the
33 * verb array use ref.verbs()[~i] (because verbs() returns a pointer just beyond the first
34 * logical verb or the last verb in memory).
35 */
36
37 class SK_API SkPathRef : public ::SkRefCnt {
38 public:
39 SK_DECLARE_INST_COUNT(SkPathRef);
40
41 class Editor {
42 public:
43 Editor(SkAutoTUnref<SkPathRef>* pathRef,
44 int incReserveVerbs = 0,
45 int incReservePoints = 0);
46
47 ~Editor() { SkDEBUGCODE(sk_atomic_dec(&fPathRef->fEditorsAttached);) }
48
49 /**
50 * Returns the array of points.
51 */
52 SkPoint* points() { return fPathRef->getPoints(); }
53 const SkPoint* points() const { return fPathRef->points(); }
54
55 /**
56 * Gets the ith point. Shortcut for this->points() + i
57 */
58 SkPoint* atPoint(int i) {
59 SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
60 return this->points() + i;
61 };
62 const SkPoint* atPoint(int i) const {
63 SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
64 return this->points() + i;
65 };
66
67 /**
68 * Adds the verb and allocates space for the number of points indicated by the verb. The
69 * return value is a pointer to where the points for the verb should be written.
70 * 'weight' is only used if 'verb' is kConic_Verb
71 */
72 SkPoint* growForVerb(int /*SkPath::Verb*/ verb, SkScalar weight = 0) {
73 SkDEBUGCODE(fPathRef->validate();)
74 return fPathRef->growForVerb(verb, weight);
75 }
76
77 /**
78 * Allocates space for multiple instances of a particular verb and the
79 * requisite points & weights.
80 * The return pointer points at the first new point (indexed normally [<i>]).
81 * If 'verb' is kConic_Verb, 'weights' will return a pointer to the
82 * space for the conic weights (indexed normally).
83 */
84 SkPoint* growForRepeatedVerb(int /*SkPath::Verb*/ verb,
85 int numVbs,
86 SkScalar** weights = NULL) {
87 return fPathRef->growForRepeatedVerb(verb, numVbs, weights);
88 }
89
90 /**
91 * Resets the path ref to a new verb and point count. The new verbs and points are
92 * uninitialized.
93 */
94 void resetToSize(int newVerbCnt, int newPointCnt, int newConicCount) {
95 fPathRef->resetToSize(newVerbCnt, newPointCnt, newConicCount);
96 }
97
98 /**
99 * Gets the path ref that is wrapped in the Editor.
100 */
101 SkPathRef* pathRef() { return fPathRef; }
102
103 void setIsOval(bool isOval) { fPathRef->setIsOval(isOval); }
104
105 void setBounds(const SkRect& rect) { fPathRef->setBounds(rect); }
106
107 private:
108 SkPathRef* fPathRef;
109 };
110
111 public:
112 /**
113 * Gets a path ref with no verbs or points.
114 */
115 static SkPathRef* CreateEmpty();
116
117 /**
118 * Returns true if all of the points in this path are finite, meaning there
119 * are no infinities and no NaNs.
120 */
121 bool isFinite() const {
122 if (fBoundsIsDirty) {
123 this->computeBounds();
124 }
125 return SkToBool(fIsFinite);
126 }
127
128 /**
129 * Returns a mask, where each bit corresponding to a SegmentMask is
130 * set if the path contains 1 or more segments of that type.
131 * Returns 0 for an empty path (no segments).
132 */
133 uint32_t getSegmentMasks() const { return fSegmentMask; }
134
135 /** Returns true if the path is an oval.
136 *
137 * @param rect returns the bounding rect of this oval. It's a circle
138 * if the height and width are the same.
139 *
140 * @return true if this path is an oval.
141 * Tracking whether a path is an oval is considered an
142 * optimization for performance and so some paths that are in
143 * fact ovals can report false.
144 */
145 bool isOval(SkRect* rect) const {
146 if (fIsOval && NULL != rect) {
147 *rect = getBounds();
148 }
149
150 return SkToBool(fIsOval);
151 }
152
153 bool hasComputedBounds() const {
154 return !fBoundsIsDirty;
155 }
156
157 /** Returns the bounds of the path's points. If the path contains 0 or 1
158 points, the bounds is set to (0,0,0,0), and isEmpty() will return true.
159 Note: this bounds may be larger than the actual shape, since curves
160 do not extend as far as their control points.
161 */
162 const SkRect& getBounds() const {
163 if (fBoundsIsDirty) {
164 this->computeBounds();
165 }
166 return fBounds;
167 }
168
169 /**
170 * Transforms a path ref by a matrix, allocating a new one only if necessary.
171 */
172 static void CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
173 const SkPathRef& src,
174 const SkMatrix& matrix);
175
176 static SkPathRef* CreateFromBuffer(SkRBuffer* buffer);
177
178 /**
179 * Rollsback a path ref to zero verbs and points with the assumption that the path ref will be
180 * repopulated with approximately the same number of verbs and points. A new path ref is created
181 * only if necessary.
182 */
183 static void Rewind(SkAutoTUnref<SkPathRef>* pathRef);
184
185 virtual ~SkPathRef() {
186 SkDEBUGCODE(this->validate();)
187 sk_free(fPoints);
188
189 SkDEBUGCODE(fPoints = NULL;)
190 SkDEBUGCODE(fVerbs = NULL;)
191 SkDEBUGCODE(fVerbCnt = 0x9999999;)
192 SkDEBUGCODE(fPointCnt = 0xAAAAAAA;)
193 SkDEBUGCODE(fPointCnt = 0xBBBBBBB;)
194 SkDEBUGCODE(fGenerationID = 0xEEEEEEEE;)
195 SkDEBUGCODE(fEditorsAttached = 0x7777777;)
196 }
197
198 int countPoints() const { SkDEBUGCODE(this->validate();) return fPointCnt; }
199 int countVerbs() const { SkDEBUGCODE(this->validate();) return fVerbCnt; }
200 int countWeights() const { SkDEBUGCODE(this->validate();) return fConicWeights.count(); }
201
202 /**
203 * Returns a pointer one beyond the first logical verb (last verb in memory order).
204 */
205 const uint8_t* verbs() const { SkDEBUGCODE(this->validate();) return fVerbs; }
206
207 /**
208 * Returns a const pointer to the first verb in memory (which is the last logical verb).
209 */
210 const uint8_t* verbsMemBegin() const { return this->verbs() - fVerbCnt; }
211
212 /**
213 * Returns a const pointer to the first point.
214 */
215 const SkPoint* points() const { SkDEBUGCODE(this->validate();) return fPoints; }
216
217 /**
218 * Shortcut for this->points() + this->countPoints()
219 */
220 const SkPoint* pointsEnd() const { return this->points() + this->countPoints(); }
221
222 const SkScalar* conicWeights() const { SkDEBUGCODE(this->validate();) return fConicWeights.begin(); }
223 const SkScalar* conicWeightsEnd() const { SkDEBUGCODE(this->validate();) return fConicWeights.end(); }
224
225 /**
226 * Convenience methods for getting to a verb or point by index.
227 */
228 uint8_t atVerb(int index) const {
229 SkASSERT((unsigned) index < (unsigned) fVerbCnt);
230 return this->verbs()[~index];
231 }
232 const SkPoint& atPoint(int index) const {
233 SkASSERT((unsigned) index < (unsigned) fPointCnt);
234 return this->points()[index];
235 }
236
237 bool operator== (const SkPathRef& ref) const;
238
239 /**
240 * Writes the path points and verbs to a buffer.
241 */
242 void writeToBuffer(SkWBuffer* buffer) const;
243
244 /**
245 * Gets the number of bytes that would be written in writeBuffer()
246 */
247 uint32_t writeSize() const;
248
249 /**
250 * Gets an ID that uniquely identifies the contents of the path ref. If two path refs have the
251 * same ID then they have the same verbs and points. However, two path refs may have the same
252 * contents but different genIDs.
253 */
254 uint32_t genID() const;
255
256 private:
257 enum SerializationOffsets {
258 kIsFinite_SerializationShift = 25, // requires 1 bit
259 kIsOval_SerializationShift = 24, // requires 1 bit
260 kSegmentMask_SerializationShift = 0 // requires 4 bits
261 };
262
263 SkPathRef() {
264 fBoundsIsDirty = true; // this also invalidates fIsFinite
265 fPointCnt = 0;
266 fVerbCnt = 0;
267 fVerbs = NULL;
268 fPoints = NULL;
269 fFreeSpace = 0;
270 fGenerationID = kEmptyGenID;
271 fSegmentMask = 0;
272 fIsOval = false;
273 SkDEBUGCODE(fEditorsAttached = 0;)
274 SkDEBUGCODE(this->validate();)
275 }
276
277 void copy(const SkPathRef& ref, int additionalReserveVerbs, int additionalReservePoints);
278
279 // Return true if the computed bounds are finite.
280 static bool ComputePtBounds(SkRect* bounds, const SkPathRef& ref) {
281 int count = ref.countPoints();
282 if (count <= 1) { // we ignore just 1 point (moveto)
283 bounds->setEmpty();
284 return count ? ref.points()->isFinite() : true;
285 } else {
286 return bounds->setBoundsCheck(ref.points(), count);
287 }
288 }
289
290 // called, if dirty, by getBounds()
291 void computeBounds() const {
292 SkDEBUGCODE(this->validate();)
293 SkASSERT(fBoundsIsDirty);
294
295 fIsFinite = ComputePtBounds(&fBounds, *this);
296 fBoundsIsDirty = false;
297 }
298
299 void setBounds(const SkRect& rect) {
300 SkASSERT(rect.fLeft <= rect.fRight && rect.fTop <= rect.fBottom);
301 fBounds = rect;
302 fBoundsIsDirty = false;
303 fIsFinite = fBounds.isFinite();
304 }
305
306 /** Makes additional room but does not change the counts or change the genID */
307 void incReserve(int additionalVerbs, int additionalPoints) {
308 SkDEBUGCODE(this->validate();)
309 size_t space = additionalVerbs * sizeof(uint8_t) + additionalPoints * sizeof (SkPoint);
310 this->makeSpace(space);
311 SkDEBUGCODE(this->validate();)
312 }
313
314 /** Resets the path ref with verbCount verbs and pointCount points, all uninitialized. Also
315 * allocates space for reserveVerb additional verbs and reservePoints additional points.*/
316 void resetToSize(int verbCount, int pointCount, int conicCount,
317 int reserveVerbs = 0, int reservePoints = 0) {
318 SkDEBUGCODE(this->validate();)
319 fBoundsIsDirty = true; // this also invalidates fIsFinite
320 fGenerationID = 0;
321
322 fSegmentMask = 0;
323 fIsOval = false;
324
325 size_t newSize = sizeof(uint8_t) * verbCount + sizeof(SkPoint) * pointCount;
326 size_t newReserve = sizeof(uint8_t) * reserveVerbs + sizeof(SkPoint) * reservePoints;
327 size_t minSize = newSize + newReserve;
328
329 ptrdiff_t sizeDelta = this->currSize() - minSize;
330
331 if (sizeDelta < 0 || static_cast<size_t>(sizeDelta) >= 3 * minSize) {
332 sk_free(fPoints);
333 fPoints = NULL;
334 fVerbs = NULL;
335 fFreeSpace = 0;
336 fVerbCnt = 0;
337 fPointCnt = 0;
338 this->makeSpace(minSize);
339 fVerbCnt = verbCount;
340 fPointCnt = pointCount;
341 fFreeSpace -= newSize;
342 } else {
343 fPointCnt = pointCount;
344 fVerbCnt = verbCount;
345 fFreeSpace = this->currSize() - minSize;
346 }
347 fConicWeights.setCount(conicCount);
348 SkDEBUGCODE(this->validate();)
349 }
350
351 /**
352 * Increases the verb count by numVbs and point count by the required amount.
353 * The new points are uninitialized. All the new verbs are set to the specified
354 * verb. If 'verb' is kConic_Verb, 'weights' will return a pointer to the
355 * uninitialized conic weights.
356 */
357 SkPoint* growForRepeatedVerb(int /*SkPath::Verb*/ verb, int numVbs, SkScalar** weights);
358
359 /**
360 * Increases the verb count 1, records the new verb, and creates room for the requisite number
361 * of additional points. A pointer to the first point is returned. Any new points are
362 * uninitialized.
363 */
364 SkPoint* growForVerb(int /*SkPath::Verb*/ verb, SkScalar weight);
365
366 /**
367 * Ensures that the free space available in the path ref is >= size. The verb and point counts
368 * are not changed.
369 */
370 void makeSpace(size_t size) {
371 SkDEBUGCODE(this->validate();)
372 ptrdiff_t growSize = size - fFreeSpace;
373 if (growSize <= 0) {
374 return;
375 }
376 size_t oldSize = this->currSize();
377 // round to next multiple of 8 bytes
378 growSize = (growSize + 7) & ~static_cast<size_t>(7);
379 // we always at least double the allocation
380 if (static_cast<size_t>(growSize) < oldSize) {
381 growSize = oldSize;
382 }
383 if (growSize < kMinSize) {
384 growSize = kMinSize;
385 }
386 size_t newSize = oldSize + growSize;
387 // Note that realloc could memcpy more than we need. It seems to be a win anyway. TODO:
388 // encapsulate this.
389 fPoints = reinterpret_cast<SkPoint*>(sk_realloc_throw(fPoints, newSize));
390 size_t oldVerbSize = fVerbCnt * sizeof(uint8_t);
391 void* newVerbsDst = reinterpret_cast<void*>(
392 reinterpret_cast<intptr_t>(fPoints) + newSize - oldVerbSize);
393 void* oldVerbsSrc = reinterpret_cast<void*>(
394 reinterpret_cast<intptr_t>(fPoints) + oldSize - oldVerbSize);
395 memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
396 fVerbs = reinterpret_cast<uint8_t*>(reinterpret_cast<intptr_t>(fPoints) + newSize);
397 fFreeSpace += growSize;
398 SkDEBUGCODE(this->validate();)
399 }
400
401 /**
402 * Private, non-const-ptr version of the public function verbsMemBegin().
403 */
404 uint8_t* verbsMemWritable() {
405 SkDEBUGCODE(this->validate();)
406 return fVerbs - fVerbCnt;
407 }
408
409 /**
410 * Gets the total amount of space allocated for verbs, points, and reserve.
411 */
412 size_t currSize() const {
413 return reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints);
414 }
415
416 SkDEBUGCODE(void validate() const;)
417
418 /**
419 * Called the first time someone calls CreateEmpty to actually create the singleton.
420 */
421 static void CreateEmptyImpl(int/*unused*/);
422
423 void setIsOval(bool isOval) { fIsOval = isOval; }
424
425 SkPoint* getPoints() {
426 SkDEBUGCODE(this->validate();)
427 fIsOval = false;
428 return fPoints;
429 }
430
431 enum {
432 kMinSize = 256,
433 };
434
435 mutable SkRect fBounds;
436 uint8_t fSegmentMask;
437 mutable uint8_t fBoundsIsDirty;
438 mutable SkBool8 fIsFinite; // only meaningful if bounds are valid
439 mutable SkBool8 fIsOval;
440
441 SkPoint* fPoints; // points to begining of the allocation
442 uint8_t* fVerbs; // points just past the end of the allocation (verbs grow backwards)
443 int fVerbCnt;
444 int fPointCnt;
445 size_t fFreeSpace; // redundant but saves computation
446 SkTDArray<SkScalar> fConicWeights;
447
448 enum {
449 kEmptyGenID = 1, // GenID reserved for path ref with zero points and zero verbs.
450 };
451 mutable uint32_t fGenerationID;
452 SkDEBUGCODE(int32_t fEditorsAttached;) // assert that only one editor in use at any time.
453
454 friend class PathRefTest_Private;
455 typedef SkRefCnt INHERITED;
456 };
457
458 #endif

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