| |
| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| |
| #ifndef GrStencil_DEFINED |
| #define GrStencil_DEFINED |
| |
| #include "GrTypes.h" |
| #include "SkRegion.h" |
| |
| /** |
| * Gr uses the stencil buffer to implement complex clipping inside the |
| * GrDrawTarget class. The GrDrawTarget makes a subset of the stencil buffer |
| * bits available for other uses by external code (clients). Client code can |
| * modify these bits. GrDrawTarget will ignore ref, mask, and writemask bits |
| * provided by clients that overlap the bits used to implement clipping. |
| * |
| * When code outside the GrDrawTarget class uses the stencil buffer the contract |
| * is as follows: |
| * |
| * > Normal stencil funcs allow the client to pass / fail regardless of the |
| * reserved clip bits. |
| * > Additional functions allow a test against the clip along with a limited |
| * set of tests against the client bits. |
| * > Client can assume all client bits are zero initially. |
| * > Client must ensure that after all its passes are finished it has only |
| * written to the color buffer in the region inside the clip. Furthermore, it |
| * must zero all client bits that were modifed (both inside and outside the |
| * clip). |
| */ |
| |
| /** |
| * Determines which pixels pass / fail the stencil test. |
| * Stencil test passes if (ref & mask) FUNC (stencil & mask) is true |
| */ |
| enum GrStencilFunc { |
| kAlways_StencilFunc = 0, |
| kNever_StencilFunc, |
| kGreater_StencilFunc, |
| kGEqual_StencilFunc, |
| kLess_StencilFunc, |
| kLEqual_StencilFunc, |
| kEqual_StencilFunc, |
| kNotEqual_StencilFunc, |
| |
| // Gr stores the current clip in the |
| // stencil buffer in the high bits that |
| // are not directly accessible modifiable |
| // via the GrDrawTarget interface. The below |
| // stencil funcs test against the current |
| // clip in addition to the GrDrawTarget |
| // client's stencil bits. |
| |
| // pass if inside the clip |
| kAlwaysIfInClip_StencilFunc, |
| kEqualIfInClip_StencilFunc, |
| kLessIfInClip_StencilFunc, |
| kLEqualIfInClip_StencilFunc, |
| kNonZeroIfInClip_StencilFunc, // this one forces the ref to be 0 |
| |
| // counts |
| kStencilFuncCount, |
| kClipStencilFuncCount = kNonZeroIfInClip_StencilFunc - |
| kAlwaysIfInClip_StencilFunc + 1, |
| kBasicStencilFuncCount = kStencilFuncCount - kClipStencilFuncCount |
| }; |
| |
| /** |
| * Operations to perform based on whether stencil test passed failed. |
| */ |
| enum GrStencilOp { |
| kKeep_StencilOp = 0, // preserve existing stencil value |
| kReplace_StencilOp, // replace with reference value from stencl test |
| kIncWrap_StencilOp, // increment and wrap at max |
| kIncClamp_StencilOp, // increment and clamp at max |
| kDecWrap_StencilOp, // decrement and wrap at 0 |
| kDecClamp_StencilOp, // decrement and clamp at 0 |
| kZero_StencilOp, // zero stencil bits |
| kInvert_StencilOp, // invert stencil bits |
| |
| kStencilOpCount |
| }; |
| |
| enum GrStencilFlags { |
| kIsDisabled_StencilFlag = 0x1, |
| kNotDisabled_StencilFlag = 0x2, |
| kDoesWrite_StencilFlag = 0x4, |
| kDoesNotWrite_StencilFlag = 0x8, |
| }; |
| |
| /** |
| * GrStencilState needs to be a class with accessors and setters so that it |
| * can maintain flags related to its current state. However, we also want to |
| * be able to declare pre-made stencil settings at compile time (without |
| * inserting static initializer code). So all the data members are in this |
| * struct. A macro defined after the class can be used to jam an instance of |
| * this struct that is created from an initializer list into a |
| * GrStencilSettings. (We hang our heads in shame.) |
| */ |
| struct GrStencilSettingsStruct { |
| uint8_t fPassOps[2]; // op to perform when faces pass (GrStencilOp) |
| uint8_t fFailOps[2]; // op to perform when faces fail (GrStencilOp) |
| uint8_t fFuncs[2]; // test function for faces (GrStencilFunc) |
| uint8_t fPad0; |
| uint8_t fPad1; |
| uint16_t fFuncMasks[2]; // mask for face tests |
| uint16_t fFuncRefs[2]; // reference values for face tests |
| uint16_t fWriteMasks[2]; // stencil write masks |
| mutable uint32_t fFlags; |
| }; |
| // We rely on this being packed and aligned (memcmp'ed and memcpy'ed) |
| GR_STATIC_ASSERT(sizeof(GrStencilSettingsStruct) % 4 == 0); |
| GR_STATIC_ASSERT(sizeof(GrStencilSettingsStruct) == |
| 4*sizeof(uint8_t) + // ops |
| 2*sizeof(uint8_t) + // funcs |
| 2*sizeof(uint8_t) + // pads |
| 2*sizeof(uint16_t) + // func masks |
| 2*sizeof(uint16_t) + // ref values |
| 2*sizeof(uint16_t) + // write masks |
| sizeof(uint32_t)); // flags |
| |
| // This macro is used to compute the GrStencilSettingsStructs flags |
| // associated to disabling. It is used both to define constant structure |
| // initializers and inside GrStencilSettings::isDisabled() |
| // |
| #define GR_STENCIL_SETTINGS_IS_DISABLED( \ |
| FRONT_PASS_OP, BACK_PASS_OP, \ |
| FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC) \ |
| ((FRONT_PASS_OP) == kKeep_StencilOp && \ |
| (BACK_PASS_OP) == kKeep_StencilOp && \ |
| (FRONT_FAIL_OP) == kKeep_StencilOp && \ |
| (BACK_FAIL_OP) == kKeep_StencilOp && \ |
| (FRONT_FUNC) == kAlways_StencilFunc && \ |
| (BACK_FUNC) == kAlways_StencilFunc) |
| |
| #define GR_STENCIL_SETTINGS_DOES_WRITE( \ |
| FRONT_PASS_OP, BACK_PASS_OP, \ |
| FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC) \ |
| (!(((FRONT_FUNC) == kNever_StencilFunc || \ |
| (FRONT_PASS_OP) == kKeep_StencilOp) && \ |
| ((BACK_FUNC) == kNever_StencilFunc || \ |
| (BACK_PASS_OP) == kKeep_StencilOp) && \ |
| ((FRONT_FUNC) == kAlways_StencilFunc || \ |
| (FRONT_FAIL_OP) == kKeep_StencilOp) && \ |
| ((BACK_FUNC) == kAlways_StencilFunc || \ |
| (BACK_FAIL_OP) == kKeep_StencilOp))) |
| |
| #define GR_STENCIL_SETTINGS_DEFAULT_FLAGS( \ |
| FRONT_PASS_OP, BACK_PASS_OP, \ |
| FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC) \ |
| ((GR_STENCIL_SETTINGS_IS_DISABLED(FRONT_PASS_OP,BACK_PASS_OP, \ |
| FRONT_FAIL_OP,BACK_FAIL_OP,FRONT_FUNC,BACK_FUNC) ? \ |
| kIsDisabled_StencilFlag : kNotDisabled_StencilFlag) | \ |
| (GR_STENCIL_SETTINGS_DOES_WRITE(FRONT_PASS_OP,BACK_PASS_OP, \ |
| FRONT_FAIL_OP,BACK_FAIL_OP,FRONT_FUNC,BACK_FUNC) ? \ |
| kDoesWrite_StencilFlag : kDoesNotWrite_StencilFlag)) |
| |
| /** |
| * Class representing stencil state. |
| */ |
| class GrStencilSettings : private GrStencilSettingsStruct { |
| |
| public: |
| enum Face { |
| kFront_Face = 0, |
| kBack_Face = 1, |
| }; |
| |
| GrStencilSettings() { |
| fPad0 = fPad1 = 0; |
| this->setDisabled(); |
| } |
| |
| GrStencilOp passOp(Face f) const { return static_cast<GrStencilOp>(fPassOps[f]); } |
| GrStencilOp failOp(Face f) const { return static_cast<GrStencilOp>(fFailOps[f]); } |
| GrStencilFunc func(Face f) const { return static_cast<GrStencilFunc>(fFuncs[f]); } |
| uint16_t funcMask(Face f) const { return fFuncMasks[f]; } |
| uint16_t funcRef(Face f) const { return fFuncRefs[f]; } |
| uint16_t writeMask(Face f) const { return fWriteMasks[f]; } |
| |
| void setPassOp(Face f, GrStencilOp op) { fPassOps[f] = op; fFlags = 0;} |
| void setFailOp(Face f, GrStencilOp op) { fFailOps[f] = op; fFlags = 0;} |
| void setFunc(Face f, GrStencilFunc func) { fFuncs[f] = func; fFlags = 0;} |
| void setFuncMask(Face f, unsigned short mask) { fFuncMasks[f] = mask; } |
| void setFuncRef(Face f, unsigned short ref) { fFuncRefs[f] = ref; } |
| void setWriteMask(Face f, unsigned short writeMask) { fWriteMasks[f] = writeMask; } |
| |
| void copyFrontSettingsToBack() { |
| fPassOps[kBack_Face] = fPassOps[kFront_Face]; |
| fFailOps[kBack_Face] = fFailOps[kFront_Face]; |
| fFuncs[kBack_Face] = fFuncs[kFront_Face]; |
| fFuncMasks[kBack_Face] = fFuncMasks[kFront_Face]; |
| fFuncRefs[kBack_Face] = fFuncRefs[kFront_Face]; |
| fWriteMasks[kBack_Face] = fWriteMasks[kFront_Face]; |
| fFlags = 0; |
| } |
| |
| void setSame(GrStencilOp passOp, |
| GrStencilOp failOp, |
| GrStencilFunc func, |
| unsigned short funcMask, |
| unsigned short funcRef, |
| unsigned short writeMask) { |
| fPassOps[kFront_Face] = fPassOps[kBack_Face] = passOp; |
| fFailOps[kFront_Face] = fFailOps[kBack_Face] = failOp; |
| fFuncs[kFront_Face] = fFuncs[kBack_Face] = func; |
| fFuncMasks[kFront_Face] = fFuncMasks[kBack_Face] = funcMask; |
| fFuncRefs[kFront_Face] = fFuncRefs[kBack_Face] = funcRef; |
| fWriteMasks[kFront_Face] = fWriteMasks[kBack_Face] = writeMask; |
| fFlags = 0; |
| } |
| |
| void setDisabled() { |
| memset(this, 0, sizeof(*this)); |
| GR_STATIC_ASSERT(0 == kKeep_StencilOp); |
| GR_STATIC_ASSERT(0 == kAlways_StencilFunc); |
| fFlags = kIsDisabled_StencilFlag | kDoesNotWrite_StencilFlag; |
| } |
| |
| bool isTwoSided() const { |
| return fPassOps[kFront_Face] != fPassOps[kBack_Face] || |
| fFailOps[kFront_Face] != fFailOps[kBack_Face] || |
| fFuncs[kFront_Face] != fFuncs[kBack_Face] || |
| fFuncMasks[kFront_Face] != fFuncMasks[kBack_Face] || |
| fFuncRefs[kFront_Face] != fFuncRefs[kBack_Face] || |
| fWriteMasks[kFront_Face] != fWriteMasks[kBack_Face]; |
| } |
| |
| bool usesWrapOp() const { |
| return kIncWrap_StencilOp == fPassOps[kFront_Face] || |
| kDecWrap_StencilOp == fPassOps[kFront_Face] || |
| kIncWrap_StencilOp == fPassOps[kBack_Face] || |
| kDecWrap_StencilOp == fPassOps[kBack_Face] || |
| kIncWrap_StencilOp == fFailOps[kFront_Face] || |
| kDecWrap_StencilOp == fFailOps[kFront_Face] || |
| kIncWrap_StencilOp == fFailOps[kBack_Face] || |
| kDecWrap_StencilOp == fFailOps[kBack_Face]; |
| } |
| |
| bool isDisabled() const { |
| if (fFlags & kIsDisabled_StencilFlag) { |
| return true; |
| } |
| if (fFlags & kNotDisabled_StencilFlag) { |
| return false; |
| } |
| bool disabled = GR_STENCIL_SETTINGS_IS_DISABLED( |
| fPassOps[kFront_Face], fPassOps[kBack_Face], |
| fFailOps[kFront_Face], fFailOps[kBack_Face], |
| fFuncs[kFront_Face], fFuncs[kBack_Face]); |
| fFlags |= disabled ? kIsDisabled_StencilFlag : kNotDisabled_StencilFlag; |
| return disabled; |
| } |
| |
| bool doesWrite() const { |
| if (fFlags & kDoesWrite_StencilFlag) { |
| return true; |
| } |
| if (fFlags & kDoesNotWrite_StencilFlag) { |
| return false; |
| } |
| bool writes = GR_STENCIL_SETTINGS_DOES_WRITE( |
| fPassOps[kFront_Face], fPassOps[kBack_Face], |
| fFailOps[kFront_Face], fFailOps[kBack_Face], |
| fFuncs[kFront_Face], fFuncs[kBack_Face]); |
| fFlags |= writes ? kDoesWrite_StencilFlag : kDoesNotWrite_StencilFlag; |
| return writes; |
| } |
| |
| void invalidate() { |
| // write an illegal value to the first member |
| fPassOps[0] = (GrStencilOp)(uint8_t)-1; |
| fFlags = 0; |
| } |
| |
| bool operator == (const GrStencilSettings& s) const { |
| static const size_t gCompareSize = sizeof(GrStencilSettings) - |
| sizeof(fFlags); |
| SkASSERT((const char*)&fFlags + sizeof(fFlags) == |
| (const char*)this + sizeof(GrStencilSettings)); |
| if (this->isDisabled() & s.isDisabled()) { // using & not && |
| return true; |
| } |
| return 0 == memcmp(this, &s, gCompareSize); |
| } |
| |
| bool operator != (const GrStencilSettings& s) const { |
| return !(*this == s); |
| } |
| |
| GrStencilSettings& operator =(const GrStencilSettings& s) { |
| memcpy(this, &s, sizeof(GrStencilSettings)); |
| return *this; |
| } |
| |
| private: |
| friend class GrClipMaskManager; |
| |
| enum { |
| kMaxStencilClipPasses = 2 // maximum number of passes to add a clip |
| // element to the stencil buffer. |
| }; |
| |
| /** |
| * Given a thing to draw into the stencil clip, a fill type, and a set op |
| * this function determines: |
| * 1. Whether the thing can be draw directly to the stencil clip or |
| * needs to be drawn to the client portion of the stencil first. |
| * 2. How many passes are needed. |
| * 3. What those passes are. |
| * 4. The fill rule that should actually be used to render (will |
| * always be non-inverted). |
| * |
| * @param op the set op to combine this element with the |
| * existing clip |
| * @param stencilClipMask mask with just the stencil bit used for clipping |
| * enabled. |
| * @param invertedFill is this path inverted |
| * @param numPasses out: the number of passes needed to add the |
| * element to the clip. |
| * @param settings out: the stencil settings to use for each pass |
| * |
| * @return true if the clip element's geometry can be drawn directly to the |
| * stencil clip bit. Will only be true if canBeDirect is true. |
| * numPasses will be 1 if return value is true. |
| */ |
| static bool GetClipPasses(SkRegion::Op op, |
| bool canBeDirect, |
| unsigned int stencilClipMask, |
| bool invertedFill, |
| int* numPasses, |
| GrStencilSettings settings[kMaxStencilClipPasses]); |
| }; |
| |
| GR_STATIC_ASSERT(sizeof(GrStencilSettingsStruct) == sizeof(GrStencilSettings)); |
| |
| #define GR_STATIC_CONST_STENCIL_STRUCT(STRUCT_NAME, \ |
| FRONT_PASS_OP, BACK_PASS_OP, \ |
| FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC, \ |
| FRONT_MASK, BACK_MASK, \ |
| FRONT_REF, BACK_REF, \ |
| FRONT_WRITE_MASK, BACK_WRITE_MASK) \ |
| static const GrStencilSettingsStruct STRUCT_NAME = { \ |
| {(FRONT_PASS_OP), (BACK_PASS_OP) }, \ |
| {(FRONT_FAIL_OP), (BACK_FAIL_OP) }, \ |
| {(FRONT_FUNC), (BACK_FUNC) }, \ |
| (0), (0), \ |
| {(FRONT_MASK), (BACK_MASK) }, \ |
| {(FRONT_REF), (BACK_REF) }, \ |
| {(FRONT_WRITE_MASK), (BACK_WRITE_MASK)}, \ |
| GR_STENCIL_SETTINGS_DEFAULT_FLAGS( \ |
| FRONT_PASS_OP, BACK_PASS_OP, FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC) \ |
| }; |
| |
| #define GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(STRUCT_PTR) \ |
| reinterpret_cast<const GrStencilSettings*>(STRUCT_PTR) |
| |
| #define GR_STATIC_CONST_SAME_STENCIL_STRUCT(STRUCT_NAME, \ |
| PASS_OP, FAIL_OP, FUNC, MASK, REF, WRITE_MASK) \ |
| GR_STATIC_CONST_STENCIL_STRUCT(STRUCT_NAME, (PASS_OP), (PASS_OP), \ |
| (FAIL_OP),(FAIL_OP), (FUNC), (FUNC), (MASK), (MASK), (REF), (REF), \ |
| (WRITE_MASK),(WRITE_MASK)) |
| |
| #define GR_STATIC_CONST_STENCIL(NAME, \ |
| FRONT_PASS_OP, BACK_PASS_OP, \ |
| FRONT_FAIL_OP, BACK_FAIL_OP, \ |
| FRONT_FUNC, BACK_FUNC, \ |
| FRONT_MASK, BACK_MASK, \ |
| FRONT_REF, BACK_REF, \ |
| FRONT_WRITE_MASK, BACK_WRITE_MASK) \ |
| GR_STATIC_CONST_STENCIL_STRUCT(NAME ## _STRUCT, \ |
| (FRONT_PASS_OP),(BACK_PASS_OP),(FRONT_FAIL_OP),(BACK_FAIL_OP), \ |
| (FRONT_FUNC),(BACK_FUNC),(FRONT_MASK),(BACK_MASK), \ |
| (FRONT_REF),(BACK_REF),(FRONT_WRITE_MASK),(BACK_WRITE_MASK)) \ |
| static const GrStencilSettings& NAME = \ |
| *GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(&(NAME ## _STRUCT)); |
| |
| |
| #define GR_STATIC_CONST_SAME_STENCIL(NAME, \ |
| PASS_OP, FAIL_OP, FUNC, MASK, REF, WRITE_MASK) \ |
| GR_STATIC_CONST_STENCIL(NAME, (PASS_OP), (PASS_OP), (FAIL_OP), \ |
| (FAIL_OP), (FUNC), (FUNC), (MASK), (MASK), (REF), (REF), (WRITE_MASK), \ |
| (WRITE_MASK)) |
| |
| #endif |
