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/*
* 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 "SkMSAN.h"
#include "SkNx.h"
#include "SkXfermode_proccoeff.h"
namespace {
// Most xfermodes can be done most efficiently 4 pixels at a time in 8 or 16-bit fixed point.
#define XFERMODE(Xfermode) \
struct Xfermode { Sk4px operator()(const Sk4px&, const Sk4px&) const; }; \
inline Sk4px Xfermode::operator()(const Sk4px& d, const Sk4px& s) const
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 ()(s,d); }
XFERMODE(DstOut) { return SrcOut ()(s,d); }
XFERMODE(DstOver) { return SrcOver()(s,d); }
// [ S * Da + (1 - Sa) * D]
XFERMODE(SrcATop) { return (s * d.alphas() + d * s.alphas().inv()).div255(); }
XFERMODE(DstATop) { return SrcATop()(s,d); }
//[ 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()(s,d); }
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(Xfermode) \
struct Xfermode { Sk4f operator()(const Sk4f&, const Sk4f&) const; }; \
inline Sk4f Xfermode::operator()(const Sk4f& d, const Sk4f& s) const
static inline Sk4f a_rgb(const Sk4f& a, const Sk4f& rgb) {
static_assert(SK_A32_SHIFT == 24, "");
return a * Sk4f(0,0,0,1) + rgb * Sk4f(1,1,1,0);
}
static inline Sk4f alphas(const Sk4f& f) {
return f[SK_A32_SHIFT/8];
}
XFERMODE(ColorDodge) {
auto sa = alphas(s),
da = alphas(d),
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 a_rgb(srcover, colors);
}
XFERMODE(ColorBurn) {
auto sa = alphas(s),
da = alphas(d),
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 a_rgb(srcover, colors);
}
XFERMODE(SoftLight) {
auto sa = alphas(s),
da = alphas(d),
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 a_rgb(alpha, colors);
}
#undef XFERMODE
// A reasonable fallback mode for doing AA is to simply apply the transfermode first,
// then linearly interpolate the AA.
template <typename Xfermode>
static Sk4px xfer_aa(const Sk4px& d, const Sk4px& s, const Sk4px& aa) {
Sk4px bw = Xfermode()(d, s);
return (bw * aa + d * aa.inv()).div255();
}
// For some transfermodes we specialize AA, either for correctness or performance.
#define XFERMODE_AA(Xfermode) \
template <> Sk4px xfer_aa<Xfermode>(const Sk4px& d, const Sk4px& s, const 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
// Src and Clear modes are safe to use with unitialized dst buffers,
// even if the implementation branches based on bytes from dst (e.g. asserts in Debug mode).
// For those modes, just lie to MSAN that dst is always intialized.
template <typename Xfermode> static void mark_dst_initialized_if_safe(void*, void*) {}
template <> void mark_dst_initialized_if_safe<Src>(void* dst, void* end) {
sk_msan_mark_initialized(dst, end, "Src doesn't read dst.");
}
template <> void mark_dst_initialized_if_safe<Clear>(void* dst, void* end) {
sk_msan_mark_initialized(dst, end, "Clear doesn't read dst.");
}
template <typename Xfermode>
class Sk4pxXfermode : public SkProcCoeffXfermode {
public:
Sk4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
: INHERITED(rec, mode) {}
void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
if (nullptr == aa) {
Sk4px::MapDstSrc(n, dst, src, Xfermode());
} else {
Sk4px::MapDstSrcAlpha(n, dst, src, aa, xfer_aa<Xfermode>);
}
}
void xfer16(uint16_t dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
mark_dst_initialized_if_safe<Xfermode>(dst, dst+n);
SkPMColor dst32[4];
while (n >= 4) {
dst32[0] = SkPixel16ToPixel32(dst[0]);
dst32[1] = SkPixel16ToPixel32(dst[1]);
dst32[2] = SkPixel16ToPixel32(dst[2]);
dst32[3] = SkPixel16ToPixel32(dst[3]);
this->xfer32(dst32, src, 4, aa);
dst[0] = SkPixel32ToPixel16(dst32[0]);
dst[1] = SkPixel32ToPixel16(dst32[1]);
dst[2] = SkPixel32ToPixel16(dst32[2]);
dst[3] = SkPixel32ToPixel16(dst32[3]);
dst += 4;
src += 4;
aa += aa ? 4 : 0;
n -= 4;
}
while (n) {
SkPMColor dst32 = SkPixel16ToPixel32(*dst);
this->xfer32(&dst32, src, 1, aa);
*dst = SkPixel32ToPixel16(dst32);
dst += 1;
src += 1;
aa += aa ? 1 : 0;
n -= 1;
}
}
private:
typedef SkProcCoeffXfermode INHERITED;
};
template <typename Xfermode>
class Sk4fXfermode : public SkProcCoeffXfermode {
public:
Sk4fXfermode(const ProcCoeff& rec, SkXfermode::Mode mode)
: INHERITED(rec, mode) {}
void xfer32(SkPMColor dst[], const SkPMColor src[], int n, const SkAlpha aa[]) const override {
for (int i = 0; i < n; i++) {
dst[i] = Xfer32_1(dst[i], src[i], aa ? aa+i : nullptr);
}
}
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 = Xfer32_1(dst32, src[i], aa ? aa+i : nullptr);
dst[i] = SkPixel32ToPixel16(dst32);
}
}
private:
static SkPMColor Xfer32_1(SkPMColor dst, const SkPMColor src, const SkAlpha* aa) {
Sk4f d = Load(dst),
s = Load(src),
b = Xfermode()(d, s);
if (aa) {
Sk4f a = Sk4f(*aa) * Sk4f(1.0f/255);
b = b*a + d*(Sk4f(1)-a);
}
return Round(b);
}
static Sk4f Load(SkPMColor c) {
return SkNx_cast<float>(Sk4b::Load(&c)) * Sk4f(1.0f/255);
}
static SkPMColor Round(const Sk4f& f) {
SkPMColor c;
SkNx_cast<uint8_t>(f * Sk4f(255) + Sk4f(0.5f)).store(&c);
return c;
}
typedef SkProcCoeffXfermode INHERITED;
};
} // namespace
namespace SK_OPTS_NS {
static SkXfermode* create_xfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
switch (mode) {
#define CASE(Xfermode) \
case SkXfermode::k##Xfermode##_Mode: return new Sk4pxXfermode<Xfermode>(rec, 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(Xfermode) \
case SkXfermode::k##Xfermode##_Mode: return new Sk4fXfermode<Xfermode>(rec, mode)
CASE(ColorDodge);
CASE(ColorBurn);
CASE(SoftLight);
#undef CASE
default: break;
}
return nullptr;
}
} // namespace SK_OPTS_NS
#endif//Sk4pxXfermode_DEFINED