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

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

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1
2 /*
3 * Copyright 2005 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 SkRegion_DEFINED
11 #define SkRegion_DEFINED
12
13 #include "SkRect.h"
14
15 class SkPath;
16 class SkRgnBuilder;
17
18 namespace android {
19 class Region;
20 }
21
22 #define SkRegion_gEmptyRunHeadPtr ((SkRegion::RunHead*)-1)
23 #define SkRegion_gRectRunHeadPtr 0
24
25 /** \class SkRegion
26
27 The SkRegion class encapsulates the geometric region used to specify
28 clipping areas for drawing.
29 */
30 class SK_API SkRegion {
31 public:
32 typedef int32_t RunType;
33 enum {
34 kRunTypeSentinel = 0x7FFFFFFF
35 };
36
37 SkRegion();
38 SkRegion(const SkRegion&);
39 explicit SkRegion(const SkIRect&);
40 ~SkRegion();
41
42 SkRegion& operator=(const SkRegion&);
43
44 /**
45 * Return true if the two regions are equal. i.e. The enclose exactly
46 * the same area.
47 */
48 bool operator==(const SkRegion& other) const;
49
50 /**
51 * Return true if the two regions are not equal.
52 */
53 bool operator!=(const SkRegion& other) const {
54 return !(*this == other);
55 }
56
57 /**
58 * Replace this region with the specified region, and return true if the
59 * resulting region is non-empty.
60 */
61 bool set(const SkRegion& src) {
62 SkASSERT(&src);
63 *this = src;
64 return !this->isEmpty();
65 }
66
67 /**
68 * Swap the contents of this and the specified region. This operation
69 * is gauarenteed to never fail.
70 */
71 void swap(SkRegion&);
72
73 /** Return true if this region is empty */
74 bool isEmpty() const { return fRunHead == SkRegion_gEmptyRunHeadPtr; }
75
76 /** Return true if this region is a single, non-empty rectangle */
77 bool isRect() const { return fRunHead == SkRegion_gRectRunHeadPtr; }
78
79 /** Return true if this region consists of more than 1 rectangular area */
80 bool isComplex() const { return !this->isEmpty() && !this->isRect(); }
81
82 /**
83 * Return the bounds of this region. If the region is empty, returns an
84 * empty rectangle.
85 */
86 const SkIRect& getBounds() const { return fBounds; }
87
88 /**
89 * Returns a value that grows approximately linearly with the number of
90 * intervals comprised in the region. Empty region will return 0, Rect
91 * will return 1, Complex will return a value > 1.
92 *
93 * Use this to compare two regions, where the larger count likely
94 * indicates a more complex region.
95 */
96 int computeRegionComplexity() const;
97
98 /**
99 * Returns true if the region is non-empty, and if so, appends the
100 * boundary(s) of the region to the specified path.
101 * If the region is empty, returns false, and path is left unmodified.
102 */
103 bool getBoundaryPath(SkPath* path) const;
104
105 /**
106 * Set the region to be empty, and return false, since the resulting
107 * region is empty
108 */
109 bool setEmpty();
110
111 /**
112 * If rect is non-empty, set this region to that rectangle and return true,
113 * otherwise set this region to empty and return false.
114 */
115 bool setRect(const SkIRect&);
116
117 /**
118 * If left < right and top < bottom, set this region to that rectangle and
119 * return true, otherwise set this region to empty and return false.
120 */
121 bool setRect(int32_t left, int32_t top, int32_t right, int32_t bottom);
122
123 /**
124 * Set this region to the union of an array of rects. This is generally
125 * faster than calling region.op(rect, kUnion_Op) in a loop. If count is
126 * 0, then this region is set to the empty region.
127 * @return true if the resulting region is non-empty
128 */
129 bool setRects(const SkIRect rects[], int count);
130
131 /**
132 * Set this region to the specified region, and return true if it is
133 * non-empty.
134 */
135 bool setRegion(const SkRegion&);
136
137 /**
138 * Set this region to the area described by the path, clipped.
139 * Return true if the resulting region is non-empty.
140 * This produces a region that is identical to the pixels that would be
141 * drawn by the path (with no antialiasing) with the specified clip.
142 */
143 bool setPath(const SkPath&, const SkRegion& clip);
144
145 /**
146 * Returns true if the specified rectangle has a non-empty intersection
147 * with this region.
148 */
149 bool intersects(const SkIRect&) const;
150
151 /**
152 * Returns true if the specified region has a non-empty intersection
153 * with this region.
154 */
155 bool intersects(const SkRegion&) const;
156
157 /**
158 * Return true if the specified x,y coordinate is inside the region.
159 */
160 bool contains(int32_t x, int32_t y) const;
161
162 /**
163 * Return true if the specified rectangle is completely inside the region.
164 * This works for simple (rectangular) and complex regions, and always
165 * returns the correct result. Note: if either this region or the rectangle
166 * is empty, contains() returns false.
167 */
168 bool contains(const SkIRect&) const;
169
170 /**
171 * Return true if the specified region is completely inside the region.
172 * This works for simple (rectangular) and complex regions, and always
173 * returns the correct result. Note: if either region is empty, contains()
174 * returns false.
175 */
176 bool contains(const SkRegion&) const;
177
178 /**
179 * Return true if this region is a single rectangle (not complex) and the
180 * specified rectangle is contained by this region. Returning false is not
181 * a guarantee that the rectangle is not contained by this region, but
182 * return true is a guarantee that the rectangle is contained by this region.
183 */
184 bool quickContains(const SkIRect& r) const {
185 return this->quickContains(r.fLeft, r.fTop, r.fRight, r.fBottom);
186 }
187
188 /**
189 * Return true if this region is a single rectangle (not complex) and the
190 * specified rectangle is contained by this region. Returning false is not
191 * a guarantee that the rectangle is not contained by this region, but
192 * return true is a guarantee that the rectangle is contained by this
193 * region.
194 */
195 bool quickContains(int32_t left, int32_t top, int32_t right,
196 int32_t bottom) const {
197 SkASSERT(this->isEmpty() == fBounds.isEmpty()); // valid region
198
199 return left < right && top < bottom &&
200 fRunHead == SkRegion_gRectRunHeadPtr && // this->isRect()
201 /* fBounds.contains(left, top, right, bottom); */
202 fBounds.fLeft <= left && fBounds.fTop <= top &&
203 fBounds.fRight >= right && fBounds.fBottom >= bottom;
204 }
205
206 /**
207 * Return true if this region is empty, or if the specified rectangle does
208 * not intersect the region. Returning false is not a guarantee that they
209 * intersect, but returning true is a guarantee that they do not.
210 */
211 bool quickReject(const SkIRect& rect) const {
212 return this->isEmpty() || rect.isEmpty() ||
213 !SkIRect::Intersects(fBounds, rect);
214 }
215
216 /**
217 * Return true if this region, or rgn, is empty, or if their bounds do not
218 * intersect. Returning false is not a guarantee that they intersect, but
219 * returning true is a guarantee that they do not.
220 */
221 bool quickReject(const SkRegion& rgn) const {
222 return this->isEmpty() || rgn.isEmpty() ||
223 !SkIRect::Intersects(fBounds, rgn.fBounds);
224 }
225
226 /** Translate the region by the specified (dx, dy) amount. */
227 void translate(int dx, int dy) { this->translate(dx, dy, this); }
228
229 /**
230 * Translate the region by the specified (dx, dy) amount, writing the
231 * resulting region into dst. Note: it is legal to pass this region as the
232 * dst parameter, effectively translating the region in place. If dst is
233 * null, nothing happens.
234 */
235 void translate(int dx, int dy, SkRegion* dst) const;
236
237 /**
238 * The logical operations that can be performed when combining two regions.
239 */
240 enum Op {
241 kDifference_Op, //!< subtract the op region from the first region
242 kIntersect_Op, //!< intersect the two regions
243 kUnion_Op, //!< union (inclusive-or) the two regions
244 kXOR_Op, //!< exclusive-or the two regions
245 /** subtract the first region from the op region */
246 kReverseDifference_Op,
247 kReplace_Op //!< replace the dst region with the op region
248 };
249
250 /**
251 * Set this region to the result of applying the Op to this region and the
252 * specified rectangle: this = (this op rect).
253 * Return true if the resulting region is non-empty.
254 */
255 bool op(const SkIRect& rect, Op op) { return this->op(*this, rect, op); }
256
257 /**
258 * Set this region to the result of applying the Op to this region and the
259 * specified rectangle: this = (this op rect).
260 * Return true if the resulting region is non-empty.
261 */
262 bool op(int left, int top, int right, int bottom, Op op) {
263 SkIRect rect;
264 rect.set(left, top, right, bottom);
265 return this->op(*this, rect, op);
266 }
267
268 /**
269 * Set this region to the result of applying the Op to this region and the
270 * specified region: this = (this op rgn).
271 * Return true if the resulting region is non-empty.
272 */
273 bool op(const SkRegion& rgn, Op op) { return this->op(*this, rgn, op); }
274
275 /**
276 * Set this region to the result of applying the Op to the specified
277 * rectangle and region: this = (rect op rgn).
278 * Return true if the resulting region is non-empty.
279 */
280 bool op(const SkIRect& rect, const SkRegion& rgn, Op);
281
282 /**
283 * Set this region to the result of applying the Op to the specified
284 * region and rectangle: this = (rgn op rect).
285 * Return true if the resulting region is non-empty.
286 */
287 bool op(const SkRegion& rgn, const SkIRect& rect, Op);
288
289 /**
290 * Set this region to the result of applying the Op to the specified
291 * regions: this = (rgna op rgnb).
292 * Return true if the resulting region is non-empty.
293 */
294 bool op(const SkRegion& rgna, const SkRegion& rgnb, Op op);
295
296 #ifdef SK_BUILD_FOR_ANDROID
297 /** Returns a new char* containing the list of rectangles in this region
298 */
299 char* toString();
300 #endif
301
302 /**
303 * Returns the sequence of rectangles, sorted in Y and X, that make up
304 * this region.
305 */
306 class SK_API Iterator {
307 public:
308 Iterator() : fRgn(NULL), fDone(true) {}
309 Iterator(const SkRegion&);
310 // if we have a region, reset to it and return true, else return false
311 bool rewind();
312 // reset the iterator, using the new region
313 void reset(const SkRegion&);
314 bool done() const { return fDone; }
315 void next();
316 const SkIRect& rect() const { return fRect; }
317 // may return null
318 const SkRegion* rgn() const { return fRgn; }
319
320 private:
321 const SkRegion* fRgn;
322 const RunType* fRuns;
323 SkIRect fRect;
324 bool fDone;
325 };
326
327 /**
328 * Returns the sequence of rectangles, sorted in Y and X, that make up
329 * this region intersected with the specified clip rectangle.
330 */
331 class SK_API Cliperator {
332 public:
333 Cliperator(const SkRegion&, const SkIRect& clip);
334 bool done() { return fDone; }
335 void next();
336 const SkIRect& rect() const { return fRect; }
337
338 private:
339 Iterator fIter;
340 SkIRect fClip;
341 SkIRect fRect;
342 bool fDone;
343 };
344
345 /**
346 * Returns the sequence of runs that make up this region for the specified
347 * Y scanline, clipped to the specified left and right X values.
348 */
349 class Spanerator {
350 public:
351 Spanerator(const SkRegion&, int y, int left, int right);
352 bool next(int* left, int* right);
353
354 private:
355 const SkRegion::RunType* fRuns;
356 int fLeft, fRight;
357 bool fDone;
358 };
359
360 /**
361 * Write the region to the buffer, and return the number of bytes written.
362 * If buffer is NULL, it still returns the number of bytes.
363 */
364 size_t writeToMemory(void* buffer) const;
365 /**
366 * Initializes the region from the buffer
367 *
368 * @param buffer Memory to read from
369 * @param length Amount of memory available in the buffer
370 * @return number of bytes read (must be a multiple of 4) or
371 * 0 if there was not enough memory available
372 */
373 size_t readFromMemory(const void* buffer, size_t length);
374
375 /**
376 * Returns a reference to a global empty region. Just a convenience for
377 * callers that need a const empty region.
378 */
379 static const SkRegion& GetEmptyRegion();
380
381 SkDEBUGCODE(void dump() const;)
382 SkDEBUGCODE(void validate() const;)
383 SkDEBUGCODE(static void UnitTest();)
384
385 // expose this to allow for regression test on complex regions
386 SkDEBUGCODE(bool debugSetRuns(const RunType runs[], int count);)
387
388 private:
389 enum {
390 kOpCount = kReplace_Op + 1
391 };
392
393 enum {
394 // T
395 // [B N L R S]
396 // S
397 kRectRegionRuns = 7
398 };
399
400 friend class android::Region; // needed for marshalling efficiently
401
402 struct RunHead;
403
404 // allocate space for count runs
405 void allocateRuns(int count);
406 void allocateRuns(int count, int ySpanCount, int intervalCount);
407 void allocateRuns(const RunHead& src);
408
409 SkIRect fBounds;
410 RunHead* fRunHead;
411
412 void freeRuns();
413
414 /**
415 * Return the runs from this region, consing up fake runs if the region
416 * is empty or a rect. In those 2 cases, we use tmpStorage to hold the
417 * run data.
418 */
419 const RunType* getRuns(RunType tmpStorage[], int* intervals) const;
420
421 // This is called with runs[] that do not yet have their interval-count
422 // field set on each scanline. That is computed as part of this call
423 // (inside ComputeRunBounds).
424 bool setRuns(RunType runs[], int count);
425
426 int count_runtype_values(int* itop, int* ibot) const;
427
428 static void BuildRectRuns(const SkIRect& bounds,
429 RunType runs[kRectRegionRuns]);
430
431 // If the runs define a simple rect, return true and set bounds to that
432 // rect. If not, return false and ignore bounds.
433 static bool RunsAreARect(const SkRegion::RunType runs[], int count,
434 SkIRect* bounds);
435
436 /**
437 * If the last arg is null, just return if the result is non-empty,
438 * else store the result in the last arg.
439 */
440 static bool Oper(const SkRegion&, const SkRegion&, SkRegion::Op, SkRegion*);
441
442 friend struct RunHead;
443 friend class Iterator;
444 friend class Spanerator;
445 friend class SkRgnBuilder;
446 friend class SkFlatRegion;
447 };
448
449 #endif

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