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 "GrAppliedClip.h" 12 #include "GrRenderTargetContext.h" 13 #include "SkRRect.h" 14 #include "SkRect.h" 15 16 class GrContext; 17 18 /** 19 * GrClip is an abstract base class for applying a clip. It constructs a clip mask if necessary, and 20 * fills out a GrAppliedClip instructing the caller on how to set up the draw state. 21 */ 22 class GrClip { 23 public: 24 virtual bool quickContains(const SkRect&) const = 0; 25 virtual bool quickContains(const SkRRect& rrect) const { 26 return this->quickContains(rrect.getBounds()); 27 } 28 virtual void getConservativeBounds(int width, int height, SkIRect* devResult, 29 bool* isIntersectionOfRects = nullptr) const = 0; 30 /** 31 * This computes a GrAppliedClip from the clip which in turn can be used to build a GrPipeline. 32 * To determine the appropriate clipping implementation the GrClip subclass must know whether 33 * the draw will enable HW AA or uses the stencil buffer. On input 'bounds' is a conservative 34 * bounds of the draw that is to be clipped. After return 'bounds' has been intersected with a 35 * conservative bounds of the clip. A return value of false indicates that the draw can be 36 * skipped as it is fully clipped out. 37 */ 38 virtual bool apply(GrContext*, GrRenderTargetContext*, bool useHWAA, 39 bool hasUserStencilSettings, GrAppliedClip*, SkRect* bounds) const = 0; 40 41 virtual ~GrClip() {} 42 43 /** 44 * This method quickly and conservatively determines whether the entire clip is equivalent to 45 * intersection with a rrect. This will only return true if the rrect does not fully contain 46 * the render target bounds. Moreover, the returned rrect need not be contained by the render 47 * target bounds. We assume all draws will be implicitly clipped by the render target bounds. 48 * 49 * @param rtBounds The bounds of the render target that the clip will be applied to. 50 * @param rrect If return is true rrect will contain the rrect equivalent to the clip within 51 * rtBounds. 52 * @param aa If return is true aa will indicate whether the rrect clip is antialiased. 53 * @return true if the clip is equivalent to a single rrect, false otherwise. 54 * 55 */ 56 virtual bool isRRect(const SkRect& rtBounds, SkRRect* rrect, GrAA* aa) const = 0; 57 58 /** 59 * This is the maximum distance that a draw may extend beyond a clip's boundary and still count 60 * count as "on the other side". We leave some slack because floating point rounding error is 61 * likely to blame. The rationale for 1e-3 is that in the coverage case (and barring unexpected 62 * rounding), as long as coverage stays within 0.5 * 1/256 of its intended value it shouldn't 63 * have any effect on the final pixel values. 64 */ 65 constexpr static SkScalar kBoundsTolerance = 1e-3f; 66 67 /** 68 * Returns true if the given query bounds count as entirely inside the clip. 69 * 70 * @param innerClipBounds device-space rect contained by the clip (SkRect or SkIRect). 71 * @param queryBounds device-space bounds of the query region. 72 */ 73 template <typename TRect> 74 constexpr static bool IsInsideClip(const TRect& innerClipBounds, const SkRect& queryBounds) { 75 return innerClipBounds.fRight > innerClipBounds.fLeft + kBoundsTolerance && 76 innerClipBounds.fBottom > innerClipBounds.fTop + kBoundsTolerance && 77 innerClipBounds.fLeft < queryBounds.fLeft + kBoundsTolerance && 78 innerClipBounds.fTop < queryBounds.fTop + kBoundsTolerance && 79 innerClipBounds.fRight > queryBounds.fRight - kBoundsTolerance && 80 innerClipBounds.fBottom > queryBounds.fBottom - kBoundsTolerance; 81 } 82 83 /** 84 * Returns true if the given query bounds count as entirely outside the clip. 85 * 86 * @param outerClipBounds device-space rect that contains the clip (SkRect or SkIRect). 87 * @param queryBounds device-space bounds of the query region. 88 */ 89 template <typename TRect> 90 constexpr static bool IsOutsideClip(const TRect& outerClipBounds, const SkRect& queryBounds) { 91 return 92 // Is the clip so small that it is effectively empty? 93 outerClipBounds.fRight - outerClipBounds.fLeft <= kBoundsTolerance || 94 outerClipBounds.fBottom - outerClipBounds.fTop <= kBoundsTolerance || 95 96 // Are the query bounds effectively outside the clip? 97 outerClipBounds.fLeft >= queryBounds.fRight - kBoundsTolerance || 98 outerClipBounds.fTop >= queryBounds.fBottom - kBoundsTolerance || 99 outerClipBounds.fRight <= queryBounds.fLeft + kBoundsTolerance || 100 outerClipBounds.fBottom <= queryBounds.fTop + kBoundsTolerance; 101 } 102 103 /** 104 * Returns the minimal integer rect that counts as containing a given set of bounds. 105 */ 106 static SkIRect GetPixelIBounds(const SkRect& bounds) { 107 return SkIRect::MakeLTRB(SkScalarFloorToInt(bounds.fLeft + kBoundsTolerance), 108 SkScalarFloorToInt(bounds.fTop + kBoundsTolerance), 109 SkScalarCeilToInt(bounds.fRight - kBoundsTolerance), 110 SkScalarCeilToInt(bounds.fBottom - kBoundsTolerance)); 111 } 112 113 /** 114 * Returns the minimal pixel-aligned rect that counts as containing a given set of bounds. 115 */ 116 static SkRect GetPixelBounds(const SkRect& bounds) { 117 return SkRect::MakeLTRB(SkScalarFloorToScalar(bounds.fLeft + kBoundsTolerance), 118 SkScalarFloorToScalar(bounds.fTop + kBoundsTolerance), 119 SkScalarCeilToScalar(bounds.fRight - kBoundsTolerance), 120 SkScalarCeilToScalar(bounds.fBottom - kBoundsTolerance)); 121 } 122 123 /** 124 * Returns true if the given rect counts as aligned with pixel boundaries. 125 */ 126 static bool IsPixelAligned(const SkRect& rect) { 127 return SkScalarAbs(SkScalarRoundToScalar(rect.fLeft) - rect.fLeft) <= kBoundsTolerance && 128 SkScalarAbs(SkScalarRoundToScalar(rect.fTop) - rect.fTop) <= kBoundsTolerance && 129 SkScalarAbs(SkScalarRoundToScalar(rect.fRight) - rect.fRight) <= kBoundsTolerance && 130 SkScalarAbs(SkScalarRoundToScalar(rect.fBottom) - rect.fBottom) <= kBoundsTolerance; 131 } 132 }; 133 134 135 /** 136 * GrHardClip never uses coverage FPs. It can only enforce the clip using the already-existing 137 * stencil buffer contents and/or fixed-function state like scissor. Always aliased if MSAA is off. 138 */ 139 class GrHardClip : public GrClip { 140 public: 141 /** 142 * Sets the appropriate hardware state modifications on GrAppliedHardClip that will implement 143 * the clip. On input 'bounds' is a conservative bounds of the draw that is to be clipped. After 144 * return 'bounds' has been intersected with a conservative bounds of the clip. A return value 145 * of false indicates that the draw can be skipped as it is fully clipped out. 146 */ 147 virtual bool apply(int rtWidth, int rtHeight, GrAppliedHardClip* out, SkRect* bounds) const = 0; 148 149 private: 150 bool apply(GrContext*, GrRenderTargetContext* rtc, bool useHWAA, bool hasUserStencilSettings, 151 GrAppliedClip* out, SkRect* bounds) const final { 152 return this->apply(rtc->width(), rtc->height(), &out->hardClip(), bounds); 153 } 154 }; 155 156 /** 157 * Specialized implementation for no clip. 158 */ 159 class GrNoClip final : public GrHardClip { 160 private: 161 bool quickContains(const SkRect&) const final { return true; } 162 bool quickContains(const SkRRect&) const final { return true; } 163 void getConservativeBounds(int width, int height, SkIRect* devResult, 164 bool* isIntersectionOfRects) const final { 165 devResult->setXYWH(0, 0, width, height); 166 if (isIntersectionOfRects) { 167 *isIntersectionOfRects = true; 168 } 169 } 170 bool apply(int rtWidth, int rtHeight, GrAppliedHardClip*, SkRect*) const final { return true; } 171 bool isRRect(const SkRect&, SkRRect*, GrAA*) const override { return false; } 172 }; 173 174 #endif 175
