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comparison: gfx/skia/trunk/include/core/SkDrawLooper.h
gfx/skia/trunk/include/core/SkDrawLooper.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:66162a9f9a04 |
|---|---|
| 1 | |
| 2 /* | |
| 3 * Copyright 2011 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 SkDrawLooper_DEFINED | |
| 11 #define SkDrawLooper_DEFINED | |
| 12 | |
| 13 #include "SkFlattenable.h" | |
| 14 | |
| 15 class SkCanvas; | |
| 16 class SkPaint; | |
| 17 struct SkRect; | |
| 18 class SkString; | |
| 19 | |
| 20 /** \class SkDrawLooper | |
| 21 Subclasses of SkDrawLooper can be attached to a SkPaint. Where they are, | |
| 22 and something is drawn to a canvas with that paint, the looper subclass will | |
| 23 be called, allowing it to modify the canvas and/or paint for that draw call. | |
| 24 More than that, via the next() method, the looper can modify the draw to be | |
| 25 invoked multiple times (hence the name loop-er), allow it to perform effects | |
| 26 like shadows or frame/fills, that require more than one pass. | |
| 27 */ | |
| 28 class SK_API SkDrawLooper : public SkFlattenable { | |
| 29 public: | |
| 30 SK_DECLARE_INST_COUNT(SkDrawLooper) | |
| 31 | |
| 32 /** | |
| 33 * Holds state during a draw. Users call next() until it returns false. | |
| 34 * | |
| 35 * Subclasses of SkDrawLooper should create a subclass of this object to | |
| 36 * hold state specific to their subclass. | |
| 37 */ | |
| 38 class SK_API Context : public SkNoncopyable { | |
| 39 public: | |
| 40 Context() {} | |
| 41 virtual ~Context() {} | |
| 42 | |
| 43 /** | |
| 44 * Called in a loop on objects returned by SkDrawLooper::createContext(). | |
| 45 * Each time true is returned, the object is drawn (possibly with a modified | |
| 46 * canvas and/or paint). When false is finally returned, drawing for the object | |
| 47 * stops. | |
| 48 * | |
| 49 * On each call, the paint will be in its original state, but the | |
| 50 * canvas will be as it was following the previous call to next() or | |
| 51 * createContext(). | |
| 52 * | |
| 53 * The implementation must ensure that, when next() finally returns | |
| 54 * false, the canvas has been restored to the state it was | |
| 55 * initially, before createContext() was first called. | |
| 56 */ | |
| 57 virtual bool next(SkCanvas* canvas, SkPaint* paint) = 0; | |
| 58 }; | |
| 59 | |
| 60 /** | |
| 61 * Called right before something is being drawn. Returns a Context | |
| 62 * whose next() method should be called until it returns false. | |
| 63 * The caller has to ensure that the storage pointer provides enough | |
| 64 * memory for the Context. The required size can be queried by calling | |
| 65 * contextSize(). It is also the caller's responsibility to destroy the | |
| 66 * object after use. | |
| 67 */ | |
| 68 virtual Context* createContext(SkCanvas*, void* storage) const = 0; | |
| 69 | |
| 70 /** | |
| 71 * Returns the number of bytes needed to store subclasses of Context (belonging to the | |
| 72 * corresponding SkDrawLooper subclass). | |
| 73 */ | |
| 74 virtual size_t contextSize() const = 0; | |
| 75 | |
| 76 | |
| 77 /** | |
| 78 * The fast bounds functions are used to enable the paint to be culled early | |
| 79 * in the drawing pipeline. If a subclass can support this feature it must | |
| 80 * return true for the canComputeFastBounds() function. If that function | |
| 81 * returns false then computeFastBounds behavior is undefined otherwise it | |
| 82 * is expected to have the following behavior. Given the parent paint and | |
| 83 * the parent's bounding rect the subclass must fill in and return the | |
| 84 * storage rect, where the storage rect is with the union of the src rect | |
| 85 * and the looper's bounding rect. | |
| 86 */ | |
| 87 virtual bool canComputeFastBounds(const SkPaint& paint) const; | |
| 88 virtual void computeFastBounds(const SkPaint& paint, | |
| 89 const SkRect& src, SkRect* dst) const; | |
| 90 | |
| 91 SK_TO_STRING_PUREVIRT() | |
| 92 SK_DEFINE_FLATTENABLE_TYPE(SkDrawLooper) | |
| 93 | |
| 94 protected: | |
| 95 SkDrawLooper() {} | |
| 96 SkDrawLooper(SkReadBuffer& buffer) : INHERITED(buffer) {} | |
| 97 | |
| 98 private: | |
| 99 typedef SkFlattenable INHERITED; | |
| 100 }; | |
| 101 | |
| 102 #endif |
