1 /*
2  * Copyright 2016 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 
9 #ifndef GrStencilSettings_DEFINED
10 #define GrStencilSettings_DEFINED
11 
12 #include "include/core/SkRegion.h"
13 #include "src/gpu/GrUserStencilSettings.h"
14 
15 class GrProcessorKeyBuilder;
16 
17 enum class GrStencilTest : uint16_t {
18     kAlways,
19     kNever,
20     kGreater,
21     kGEqual,
22     kLess,
23     kLEqual,
24     kEqual,
25     kNotEqual
26 };
27 static constexpr int kGrStencilTestCount = 1 + (int)GrStencilTest::kNotEqual;
28 
29 enum class GrStencilOp : uint8_t {
30     kKeep,
31     kZero,
32     kReplace, // Replace stencil value with fRef (only the bits enabled in fWriteMask).
33     kInvert,
34     kIncWrap,
35     kDecWrap,
36     // NOTE: clamping occurs before the write mask. So if the MSB is zero and masked out, stencil
37     // values will still wrap when using clamping ops.
38     kIncClamp,
39     kDecClamp
40 };
41 static constexpr int kGrStencilOpCount = 1 + (int)GrStencilOp::kDecClamp;
42 
43 /**
44  * This class defines concrete stencil settings that map directly to the underlying hardware. It
45  * is deduced from user stencil settings, stencil clip status, and the number of bits in the
46  * target stencil buffer.
47  */
48 class GrStencilSettings {
49 public:
GrStencilSettings()50     GrStencilSettings() { this->setDisabled(); }
GrStencilSettings(const GrUserStencilSettings & user,bool hasStencilClip,int numStencilBits)51     GrStencilSettings(const GrUserStencilSettings& user, bool hasStencilClip, int numStencilBits) {
52         this->reset(user, hasStencilClip, numStencilBits);
53     }
GrStencilSettings(const GrStencilSettings & that)54     GrStencilSettings(const GrStencilSettings& that) { this->reset(that); }
55     GrStencilSettings& operator=(const GrStencilSettings& that) { this->reset(that); return *this; }
56 
invalidate()57     void invalidate() { fFlags |= kInvalid_PrivateFlag; }
setDisabled()58     void setDisabled() { fFlags = kAll_StencilFlags; }
59     void reset(const GrUserStencilSettings&, bool hasStencilClip, int numStencilBits);
60     void reset(const GrStencilSettings&);
61 
isValid()62     bool isValid() const { return !(fFlags & kInvalid_PrivateFlag); }
isDisabled()63     bool isDisabled() const { SkASSERT(this->isValid()); return fFlags & kDisabled_StencilFlag; }
doesWrite()64     bool doesWrite() const { SkASSERT(this->isValid());
65                              return !(fFlags & kNoModifyStencil_StencilFlag); }
isTwoSided()66     bool isTwoSided() const { SkASSERT(this->isValid());
67                               return !(fFlags & kSingleSided_StencilFlag); }
usesWrapOp()68     bool usesWrapOp() const { SkASSERT(this->isValid());
69                               return !(fFlags & kNoWrapOps_StencilFlag); }
70 
71     void genKey(GrProcessorKeyBuilder* b, bool includeRefsAndMasks) const;
72 
73     bool operator!=(const GrStencilSettings& that) const { return !(*this == that); }
74     bool operator==(const GrStencilSettings&) const;
75 
76     struct Face : public GrTStencilFaceSettings<GrStencilTest, GrStencilOp> {
77         void reset(const GrUserStencilSettings::Face&, bool useStencilClip, int numStencilBits);
78         void setDisabled();
79     };
80 
singleSidedFace()81     const Face& singleSidedFace() const {
82         SkASSERT(!this->isDisabled());
83         SkASSERT(!this->isTwoSided());
84         return fCWFace;
85     }
86     // Returns the stencil settings for triangles that wind clockwise in "post-origin" space.
87     // (i.e., the space that results after a potential y-axis flip on device space for bottom-left
88     // origins.)
postOriginCWFace(GrSurfaceOrigin origin)89     const Face& postOriginCWFace(GrSurfaceOrigin origin) const {
90         SkASSERT(this->isTwoSided());
91         return (kTopLeft_GrSurfaceOrigin == origin) ? fCWFace : fCCWFace;
92     }
93     // Returns the stencil settings for triangles that wind counter-clockwise in "post-origin"
94     // space. (i.e., the space that results after a potential y-axis flip on device space for
95     // bottom-left origins.)
postOriginCCWFace(GrSurfaceOrigin origin)96     const Face& postOriginCCWFace(GrSurfaceOrigin origin) const {
97         SkASSERT(this->isTwoSided());
98         return (kTopLeft_GrSurfaceOrigin == origin) ? fCCWFace : fCWFace;
99     }
100 
101     /** Gets the user stencil settings to directly set the clip bit. */
102     static const GrUserStencilSettings* SetClipBitSettings(bool setToInside);
103 
104 private:
105     // Internal flag for backends to optionally mark their tracked stencil state as invalid.
106     // NOTE: This value is outside the declared range of GrStencilFlags, but since that type is
107     // explicitly backed by 'int', it can still represent this constant. clang 11 complains about
108     // mixing enum types in bit operations, so this works around that.
109     static constexpr GrStencilFlags kInvalid_PrivateFlag =
110             static_cast<GrStencilFlags>(kLast_StencilFlag << 1);
111 
112     uint32_t   fFlags;
113     Face       fCWFace;
114     Face       fCCWFace;
115 };
116 
117 #endif
118