Port SkXfermode opts to SkOpts.h

src/core/Sk4pxXfermode.h

-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef Sk4pxXfermode_DEFINED
-#define Sk4pxXfermode_DEFINED
-
-#include "Sk4px.h"
-#include "SkPMFloat.h"
-#include "SkXfermode_proccoeff.h"
-
-// This file is possibly included into multiple .cpp files.
-// Each gets its own independent instantiation by wrapping in an anonymous namespace.
-namespace {
-
-#if defined(SK_CPU_ARM32) && !defined(SK_ARM_HAS_NEON)
-    // Signals SkXfermode.cpp to look for runtime-detected NEON.
-    static SkProcCoeffXfermode* SkCreate4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
-        return nullptr;
-    }
-#else
-
-// Most xfermodes can be done most efficiently 4 pixels at a time in 8 or 16-bit fixed point.
-#define XFERMODE(Name) static Sk4px SK_VECTORCALL Name(Sk4px s, Sk4px d)
-
-XFERMODE(Clear) { return Sk4px::DupPMColor(0); }
-XFERMODE(Src)   { return s; }
-XFERMODE(Dst)   { return d; }
-XFERMODE(SrcIn)   { return     s.approxMulDiv255(d.alphas()      ); }
-XFERMODE(SrcOut)  { return     s.approxMulDiv255(d.alphas().inv()); }
-XFERMODE(SrcOver) { return s + d.approxMulDiv255(s.alphas().inv()); }
-XFERMODE(DstIn)   { return SrcIn  (d,s); }
-XFERMODE(DstOut)  { return SrcOut (d,s); }
-XFERMODE(DstOver) { return SrcOver(d,s); }
-
-// [ S * Da + (1 - Sa) * D]
-XFERMODE(SrcATop) { return (s * d.alphas() + d * s.alphas().inv()).div255(); }
-XFERMODE(DstATop) { return SrcATop(d,s); }
-//[ S * (1 - Da) + (1 - Sa) * D ]
-XFERMODE(Xor) { return (s * d.alphas().inv() + d * s.alphas().inv()).div255(); }
-// [S + D ]
-XFERMODE(Plus) { return s.saturatedAdd(d); }
-// [S * D ]
-XFERMODE(Modulate) { return s.approxMulDiv255(d); }
-// [S + D - S * D]
-XFERMODE(Screen) {
-    // Doing the math as S + (1-S)*D or S + (D - S*D) means the add and subtract can be done
-    // in 8-bit space without overflow.  S + (1-S)*D is a touch faster because inv() is cheap.
-    return s + d.approxMulDiv255(s.inv());
-}
-XFERMODE(Multiply) { return (s * d.alphas().inv() + d * s.alphas().inv() + s*d).div255(); }
-// [ Sa + Da - Sa*Da, Sc + Dc - 2*min(Sc*Da, Dc*Sa) ]  (And notice Sa*Da == min(Sa*Da, Da*Sa).)
-XFERMODE(Difference) {
-    auto m = Sk4px::Wide::Min(s * d.alphas(), d * s.alphas()).div255();
-    // There's no chance of underflow, and if we subtract m before adding s+d, no overflow.
-    return (s - m) + (d - m.zeroAlphas());
-}
-// [ Sa + Da - Sa*Da, Sc + Dc - 2*Sc*Dc ]
-XFERMODE(Exclusion) {
-    auto p = s.approxMulDiv255(d);
-    // There's no chance of underflow, and if we subtract p before adding src+dst, no overflow.
-    return (s - p) + (d - p.zeroAlphas());
-}
-
-// We take care to use exact math for these next few modes where alphas
-// and colors are calculated using significantly different math.  We need
-// to preserve premul invariants, and exact math makes this easier.
-//
-// TODO: Some of these implementations might be able to be sped up a bit
-// while maintaining exact math, but let's follow up with that.
-
-XFERMODE(HardLight) {
-    auto sa = s.alphas(),
-         da = d.alphas();
-
-    auto srcover = s + (d * sa.inv()).div255();
-
-    auto isLite = ((sa-s) < s).widenLoHi();
-
-    auto lite = sa*da - ((da-d)*(sa-s) << 1),
-         dark = s*d << 1,
-         both = s*da.inv() + d*sa.inv();
-
-    auto alphas = srcover;
-    auto colors = (both + isLite.thenElse(lite, dark)).div255();
-    return alphas.zeroColors() + colors.zeroAlphas();
-}
-XFERMODE(Overlay) { return HardLight(d,s); }
-
-XFERMODE(Darken) {
-    auto sa = s.alphas(),
-         da = d.alphas();
-
-    auto sda = (s*da).div255(),
-         dsa = (d*sa).div255();
-
-    auto srcover = s + (d * sa.inv()).div255(),
-         dstover = d + (s * da.inv()).div255();
-    auto alphas = srcover,
-         colors = (sda < dsa).thenElse(srcover, dstover);
-    return alphas.zeroColors() + colors.zeroAlphas();
-}
-XFERMODE(Lighten) {
-    auto sa = s.alphas(),
-         da = d.alphas();
-
-    auto sda = (s*da).div255(),
-         dsa = (d*sa).div255();
-
-    auto srcover = s + (d * sa.inv()).div255(),
-         dstover = d + (s * da.inv()).div255();
-    auto alphas = srcover,
-         colors = (dsa < sda).thenElse(srcover, dstover);
-    return alphas.zeroColors() + colors.zeroAlphas();
-}
-#undef XFERMODE
-
-// Some xfermodes use math like divide or sqrt that's best done in floats 1 pixel at a time.
-#define XFERMODE(Name) static SkPMFloat SK_VECTORCALL Name(SkPMFloat s, SkPMFloat d)
-
-XFERMODE(ColorDodge) {
-    auto sa = s.alphas(),
-         da = d.alphas(),
-         isa = Sk4f(1)-sa,
-         ida = Sk4f(1)-da;
-
-    auto srcover = s + d*isa,
-         dstover = d + s*ida,
-         otherwise = sa * Sk4f::Min(da, (d*sa)*(sa-s).approxInvert()) + s*ida + d*isa;
-
-    // Order matters here, preferring d==0 over s==sa.
-    auto colors = (d == Sk4f(0)).thenElse(dstover,
-                  (s ==      sa).thenElse(srcover,
-                                          otherwise));
-    return srcover * SkPMFloat(1,0,0,0) + colors * SkPMFloat(0,1,1,1);
-}
-XFERMODE(ColorBurn) {
-    auto sa = s.alphas(),
-         da = d.alphas(),
-         isa = Sk4f(1)-sa,
-         ida = Sk4f(1)-da;
-
-    auto srcover = s + d*isa,
-         dstover = d + s*ida,
-         otherwise = sa*(da-Sk4f::Min(da, (da-d)*sa*s.approxInvert())) + s*ida + d*isa;
-
-    // Order matters here, preferring d==da over s==0.
-    auto colors = (d ==      da).thenElse(dstover,
-                  (s == Sk4f(0)).thenElse(srcover,
-                                          otherwise));
-    return srcover * SkPMFloat(1,0,0,0) + colors * SkPMFloat(0,1,1,1);
-}
-XFERMODE(SoftLight) {
-    auto sa = s.alphas(),
-         da = d.alphas(),
-         isa = Sk4f(1)-sa,
-         ida = Sk4f(1)-da;
-
-    // Some common terms.
-    auto m  = (da > Sk4f(0)).thenElse(d / da, Sk4f(0)),
-         s2 = Sk4f(2)*s,
-         m4 = Sk4f(4)*m;
-
-    // The logic forks three ways:
-    //    1. dark src?
-    //    2. light src, dark dst?
-    //    3. light src, light dst?
-    auto darkSrc = d*(sa + (s2 - sa)*(Sk4f(1) - m)),        // Used in case 1.
-         darkDst = (m4*m4 + m4)*(m - Sk4f(1)) + Sk4f(7)*m,  // Used in case 2.
-         liteDst = m.sqrt() - m,                            // Used in case 3.
-         liteSrc = d*sa + da*(s2-sa)*(Sk4f(4)*d <= da).thenElse(darkDst, liteDst); // Case 2 or 3?
-
-    auto alpha  = s + d*isa;
-    auto colors = s*ida + d*isa + (s2 <= sa).thenElse(darkSrc, liteSrc);           // Case 1 or 2/3?
-
-    return alpha * SkPMFloat(1,0,0,0) + colors * SkPMFloat(0,1,1,1);
-}
-#undef XFERMODE
-
-// A reasonable fallback mode for doing AA is to simply apply the transfermode first,
-// then linearly interpolate the AA.
-template <Sk4px (SK_VECTORCALL *Mode)(Sk4px, Sk4px)>
-static Sk4px SK_VECTORCALL xfer_aa(Sk4px s, Sk4px d, Sk4px aa) {
-    Sk4px bw = Mode(s, d);
-    return (bw * aa + d * aa.inv()).div255();
-}
-
-// For some transfermodes we specialize AA, either for correctness or performance.
-#define XFERMODE_AA(Name) \
-    template <> Sk4px SK_VECTORCALL xfer_aa<Name>(Sk4px s, Sk4px d, Sk4px aa)
-
-// Plus' clamp needs to happen after AA.  skia:3852
-XFERMODE_AA(Plus) {  // [ clamp( (1-AA)D + (AA)(S+D) ) == clamp(D + AA*S) ]
-    return d.saturatedAdd(s.approxMulDiv255(aa));
-}
-
-#undef XFERMODE_AA
-
-class Sk4pxXfermode : public SkProcCoeffXfermode {
-public:
-    typedef Sk4px (SK_VECTORCALL *Proc4)(Sk4px, Sk4px);
-    typedef Sk4px (SK_VECTORCALL *AAProc4)(Sk4px, Sk4px, Sk4px);
-
-    Sk4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode, Proc4 proc4, AAProc4 aaproc4)
-        : INHERITED(rec, mode)
-        , fProc4(proc4)
-        , fAAProc4(aaproc4) {}
-
-    void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
-        if (NULL == aa) {
-            Sk4px::MapDstSrc(n, dst, src, [&](const Sk4px& dst4, const Sk4px& src4) {
-                return fProc4(src4, dst4);
-            });
-        } else {
-            Sk4px::MapDstSrcAlpha(n, dst, src, aa,
-                    [&](const Sk4px& dst4, const Sk4px& src4, const Sk4px& alpha) {
-                return fAAProc4(src4, dst4, alpha);
-            });
-        }
-    }
-
-    void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
-        if (NULL == aa) {
-            Sk4px::MapDstSrc(n, dst, src, [&](const Sk4px& dst4, const Sk4px& src4) {
-                return fProc4(src4, dst4);
-            });
-        } else {
-            Sk4px::MapDstSrcAlpha(n, dst, src, aa,
-                    [&](const Sk4px& dst4, const Sk4px& src4, const Sk4px& alpha) {
-                return fAAProc4(src4, dst4, alpha);
-            });
-        }
-    }
-
-private:
-    Proc4 fProc4;
-    AAProc4 fAAProc4;
-    typedef SkProcCoeffXfermode INHERITED;
-};
-
-class SkPMFloatXfermode : public SkProcCoeffXfermode {
-public:
-    typedef SkPMFloat (SK_VECTORCALL *ProcF)(SkPMFloat, SkPMFloat);
-    SkPMFloatXfermode(const ProcCoeff& rec, SkXfermode::Mode mode, ProcF procf)
-        : INHERITED(rec, mode)
-        , fProcF(procf) {}
-
-    void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
-        for (int i = 0; i < n; i++) {
-            dst[i] = aa ? this->xfer32(dst[i], src[i], aa[i])
-                        : this->xfer32(dst[i], src[i]);
-        }
-    }
-
-    void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
-        for (int i = 0; i < n; i++) {
-            SkPMColor dst32 = SkPixel16ToPixel32(dst[i]);
-            dst32 = aa ? this->xfer32(dst32, src[i], aa[i])
-                       : this->xfer32(dst32, src[i]);
-            dst[i] = SkPixel32ToPixel16(dst32);
-        }
-    }
-
-private:
-    inline SkPMColor xfer32(SkPMColor dst, SkPMColor src) const {
-        return fProcF(SkPMFloat(src), SkPMFloat(dst)).round();
-    }
-
-    inline SkPMColor xfer32(SkPMColor dst, SkPMColor src, SkAlpha aa) const {
-        SkPMFloat s(src),
-                  d(dst),
-                  b(fProcF(s,d));
-        // We do aa in full float precision before going back down to bytes, because we can!
-        SkPMFloat a = Sk4f(aa) * Sk4f(1.0f/255);
-        b = b*a + d*(Sk4f(1)-a);
-        return b.round();
-    }
-
-    ProcF fProcF;
-    typedef SkProcCoeffXfermode INHERITED;
-};
-
-static SkProcCoeffXfermode* SkCreate4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
-    switch (mode) {
-    #define CASE(Mode) case SkXfermode::k##Mode##_Mode: \
-        return SkNEW_ARGS(Sk4pxXfermode, (rec, mode, &Mode, &xfer_aa<Mode>))
-        CASE(Clear);
-        CASE(Src);
-        CASE(Dst);
-        CASE(SrcOver);
-        CASE(DstOver);
-        CASE(SrcIn);
-        CASE(DstIn);
-        CASE(SrcOut);
-        CASE(DstOut);
-        CASE(SrcATop);
-        CASE(DstATop);
-        CASE(Xor);
-        CASE(Plus);
-        CASE(Modulate);
-        CASE(Screen);
-        CASE(Multiply);
-        CASE(Difference);
-        CASE(Exclusion);
-        CASE(HardLight);
-        CASE(Overlay);
-        CASE(Darken);
-        CASE(Lighten);
-    #undef CASE
-
-    #define CASE(Mode) case SkXfermode::k##Mode##_Mode: \
-        return SkNEW_ARGS(SkPMFloatXfermode, (rec, mode, &Mode))
-        CASE(ColorDodge);
-        CASE(ColorBurn);
-        CASE(SoftLight);
-    #undef CASE
-
-        default: break;
-    }
-    return nullptr;
-}
-
-#endif
-
-} // namespace
-
-#endif//Sk4pxXfermode_DEFINED