1 /* 2 * Copyright 2010 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef GrClip_DEFINED 9 #define GrClip_DEFINED 10 11 #include "GrTypes.h" 12 #include "SkRRect.h" 13 #include "SkRect.h" 14 15 class GrAppliedClip; 16 class GrContext; 17 class GrRenderTargetContext; 18 19 /** 20 * GrClip is an abstract base class for applying a clip. It constructs a clip mask if necessary, and 21 * fills out a GrAppliedClip instructing the caller on how to set up the draw state. 22 */ 23 class GrClip { 24 public: 25 virtual bool quickContains(const SkRect&) const = 0; quickContains(const SkRRect & rrect)26 virtual bool quickContains(const SkRRect& rrect) const { 27 return this->quickContains(rrect.getBounds()); 28 } 29 virtual void getConservativeBounds(int width, int height, SkIRect* devResult, 30 bool* isIntersectionOfRects = nullptr) const = 0; 31 /** 32 * This computes a GrAppliedClip from the clip which in turn can be used to build a GrPipeline. 33 * To determine the appropriate clipping implementation the GrClip subclass must know whether 34 * the draw will enable HW AA or uses the stencil buffer. On input 'bounds' is a conservative 35 * bounds of the draw that is to be clipped. After return 'bounds' has been intersected with a 36 * conservative bounds of the clip. A return value of false indicates that the draw can be 37 * skipped as it is fully clipped out. 38 */ 39 virtual bool apply(GrContext*, GrRenderTargetContext*, bool useHWAA, 40 bool hasUserStencilSettings, GrAppliedClip* result, 41 SkRect* bounds) const = 0; 42 ~GrClip()43 virtual ~GrClip() {} 44 45 /** 46 * This method quickly and conservatively determines whether the entire clip is equivalent to 47 * intersection with a rrect. This will only return true if the rrect does not fully contain 48 * the render target bounds. Moreover, the returned rrect need not be contained by the render 49 * target bounds. We assume all draws will be implicitly clipped by the render target bounds. 50 * 51 * @param rtBounds The bounds of the render target that the clip will be applied to. 52 * @param rrect If return is true rrect will contain the rrect equivalent to the clip within 53 * rtBounds. 54 * @param aa If return is true aa will indicate whether the rrect clip is antialiased. 55 * @return true if the clip is equivalent to a single rrect, false otherwise. 56 * 57 */ 58 virtual bool isRRect(const SkRect& rtBounds, SkRRect* rrect, GrAA* aa) const = 0; 59 60 /** 61 * This is the maximum distance that a draw may extend beyond a clip's boundary and still count 62 * count as "on the other side". We leave some slack because floating point rounding error is 63 * likely to blame. The rationale for 1e-3 is that in the coverage case (and barring unexpected 64 * rounding), as long as coverage stays within 0.5 * 1/256 of its intended value it shouldn't 65 * have any effect on the final pixel values. 66 */ 67 constexpr static SkScalar kBoundsTolerance = 1e-3f; 68 69 /** 70 * Returns true if the given query bounds count as entirely inside the clip. 71 * 72 * @param innerClipBounds device-space rect contained by the clip (SkRect or SkIRect). 73 * @param queryBounds device-space bounds of the query region. 74 */ 75 template <typename TRect> IsInsideClip(const TRect & innerClipBounds,const SkRect & queryBounds)76 constexpr static bool IsInsideClip(const TRect& innerClipBounds, const SkRect& queryBounds) { 77 return innerClipBounds.fRight - innerClipBounds.fLeft > kBoundsTolerance && 78 innerClipBounds.fBottom - innerClipBounds.fTop > kBoundsTolerance && 79 innerClipBounds.fLeft < queryBounds.fLeft + kBoundsTolerance && 80 innerClipBounds.fTop < queryBounds.fTop + kBoundsTolerance && 81 innerClipBounds.fRight > queryBounds.fRight - kBoundsTolerance && 82 innerClipBounds.fBottom > queryBounds.fBottom - kBoundsTolerance; 83 } 84 85 /** 86 * Returns true if the given query bounds count as entirely outside the clip. 87 * 88 * @param outerClipBounds device-space rect that contains the clip (SkRect or SkIRect). 89 * @param queryBounds device-space bounds of the query region. 90 */ 91 template <typename TRect> IsOutsideClip(const TRect & outerClipBounds,const SkRect & queryBounds)92 constexpr static bool IsOutsideClip(const TRect& outerClipBounds, const SkRect& queryBounds) { 93 return 94 // Is the clip so small that it is effectively empty? 95 outerClipBounds.fRight - outerClipBounds.fLeft <= kBoundsTolerance || 96 outerClipBounds.fBottom - outerClipBounds.fTop <= kBoundsTolerance || 97 98 // Are the query bounds effectively outside the clip? 99 outerClipBounds.fLeft >= queryBounds.fRight - kBoundsTolerance || 100 outerClipBounds.fTop >= queryBounds.fBottom - kBoundsTolerance || 101 outerClipBounds.fRight <= queryBounds.fLeft + kBoundsTolerance || 102 outerClipBounds.fBottom <= queryBounds.fTop + kBoundsTolerance; 103 } 104 105 /** 106 * Returns the minimal integer rect that counts as containing a given set of bounds. 107 */ GetPixelIBounds(const SkRect & bounds)108 static SkIRect GetPixelIBounds(const SkRect& bounds) { 109 return SkIRect::MakeLTRB(SkScalarFloorToInt(bounds.fLeft + kBoundsTolerance), 110 SkScalarFloorToInt(bounds.fTop + kBoundsTolerance), 111 SkScalarCeilToInt(bounds.fRight - kBoundsTolerance), 112 SkScalarCeilToInt(bounds.fBottom - kBoundsTolerance)); 113 } 114 115 /** 116 * Returns the minimal pixel-aligned rect that counts as containing a given set of bounds. 117 */ GetPixelBounds(const SkRect & bounds)118 static SkRect GetPixelBounds(const SkRect& bounds) { 119 return SkRect::MakeLTRB(SkScalarFloorToScalar(bounds.fLeft + kBoundsTolerance), 120 SkScalarFloorToScalar(bounds.fTop + kBoundsTolerance), 121 SkScalarCeilToScalar(bounds.fRight - kBoundsTolerance), 122 SkScalarCeilToScalar(bounds.fBottom - kBoundsTolerance)); 123 } 124 125 /** 126 * Returns true if the given rect counts as aligned with pixel boundaries. 127 */ IsPixelAligned(const SkRect & rect)128 static bool IsPixelAligned(const SkRect& rect) { 129 return SkScalarAbs(SkScalarRoundToScalar(rect.fLeft) - rect.fLeft) <= kBoundsTolerance && 130 SkScalarAbs(SkScalarRoundToScalar(rect.fTop) - rect.fTop) <= kBoundsTolerance && 131 SkScalarAbs(SkScalarRoundToScalar(rect.fRight) - rect.fRight) <= kBoundsTolerance && 132 SkScalarAbs(SkScalarRoundToScalar(rect.fBottom) - rect.fBottom) <= kBoundsTolerance; 133 } 134 }; 135 136 /** 137 * Specialized implementation for no clip. 138 */ 139 class GrNoClip final : public GrClip { 140 private: quickContains(const SkRect &)141 bool quickContains(const SkRect&) const final { return true; } quickContains(const SkRRect &)142 bool quickContains(const SkRRect&) const final { return true; } getConservativeBounds(int width,int height,SkIRect * devResult,bool * isIntersectionOfRects)143 void getConservativeBounds(int width, int height, SkIRect* devResult, 144 bool* isIntersectionOfRects) const final { 145 devResult->setXYWH(0, 0, width, height); 146 if (isIntersectionOfRects) { 147 *isIntersectionOfRects = true; 148 } 149 } apply(GrContext *,GrRenderTargetContext *,bool,bool,GrAppliedClip *,SkRect *)150 bool apply(GrContext*, GrRenderTargetContext*, bool, bool, GrAppliedClip*, 151 SkRect*) const final { 152 return true; 153 } isRRect(const SkRect &,SkRRect *,GrAA *)154 bool isRRect(const SkRect&, SkRRect*, GrAA*) const override { return false; } 155 }; 156 157 #endif 158