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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkArithmeticMode.h"
#include "SkColorPriv.h"
#include "SkString.h"
#include "SkUnPreMultiply.h"
class SkArithmeticMode_scalar : public SkXfermode {
public:
SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4) {
fK[0] = k1;
fK[1] = k2;
fK[2] = k3;
fK[3] = k4;
}
virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
const SkAlpha aa[]) const SK_OVERRIDE;
SK_DEVELOPER_TO_STRING()
SK_DECLARE_UNFLATTENABLE_OBJECT()
private:
SkScalar fK[4];
typedef SkXfermode INHERITED;
};
static int pinToByte(int value) {
if (value < 0) {
value = 0;
} else if (value > 255) {
value = 255;
}
return value;
}
static int arith(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
int src, int dst) {
SkScalar result = SkScalarMul(k1, src * dst) +
SkScalarMul(k2, src) +
SkScalarMul(k3, dst) +
k4;
int res = SkScalarRoundToInt(result);
return pinToByte(res);
}
static int blend(int src, int dst, int scale) {
return dst + ((src - dst) * scale >> 8);
}
static bool needsUnpremul(int alpha) {
return 0 != alpha && 0xFF != alpha;
}
void SkArithmeticMode_scalar::xfer32(SkPMColor dst[], const SkPMColor src[],
int count, const SkAlpha aaCoverage[]) const {
SkScalar k1 = fK[0] / 255;
SkScalar k2 = fK[1];
SkScalar k3 = fK[2];
SkScalar k4 = fK[3] * 255;
for (int i = 0; i < count; ++i) {
if ((NULL == aaCoverage) || aaCoverage[i]) {
SkPMColor sc = src[i];
SkPMColor dc = dst[i];
int sa = SkGetPackedA32(sc);
int da = SkGetPackedA32(dc);
int srcNeedsUnpremul = needsUnpremul(sa);
int dstNeedsUnpremul = needsUnpremul(sa);
int a, r, g, b;
if (!srcNeedsUnpremul && !dstNeedsUnpremul) {
a = arith(k1, k2, k3, k4, sa, sa);
r = arith(k1, k2, k3, k4, SkGetPackedR32(sc), SkGetPackedR32(dc));
g = arith(k1, k2, k3, k4, SkGetPackedG32(sc), SkGetPackedG32(dc));
b = arith(k1, k2, k3, k4, SkGetPackedB32(sc), SkGetPackedB32(dc));
} else {
int sr = SkGetPackedR32(sc);
int sg = SkGetPackedG32(sc);
int sb = SkGetPackedB32(sc);
if (srcNeedsUnpremul) {
SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(sa);
sr = SkUnPreMultiply::ApplyScale(scale, sr);
sg = SkUnPreMultiply::ApplyScale(scale, sg);
sb = SkUnPreMultiply::ApplyScale(scale, sb);
}
int dr = SkGetPackedR32(dc);
int dg = SkGetPackedG32(dc);
int db = SkGetPackedB32(dc);
if (dstNeedsUnpremul) {
SkUnPreMultiply::Scale scale = SkUnPreMultiply::GetScale(da);
dr = SkUnPreMultiply::ApplyScale(scale, dr);
dg = SkUnPreMultiply::ApplyScale(scale, dg);
db = SkUnPreMultiply::ApplyScale(scale, db);
}
a = arith(k1, k2, k3, k4, sa, sa);
r = arith(k1, k2, k3, k4, sr, dr);
g = arith(k1, k2, k3, k4, sg, dg);
b = arith(k1, k2, k3, k4, sb, db);
}
// apply antialias coverage if necessary
if (aaCoverage && 0xFF != aaCoverage[i]) {
int scale = aaCoverage[i] + (aaCoverage[i] >> 7);
a = blend(a, SkGetPackedA32(sc), scale);
r = blend(r, SkGetPackedR32(sc), scale);
g = blend(g, SkGetPackedG32(sc), scale);
b = blend(b, SkGetPackedB32(sc), scale);
}
// turn the result back into premul
if (0xFF != a) {
int scale = a + (a >> 7);
r = SkAlphaMul(r, scale);
g = SkAlphaMul(g, scale);
b = SkAlphaMul(b, scale);
}
dst[i] = SkPackARGB32(a, r, g, b);
}
}
}
#ifdef SK_DEVELOPER
void SkArithmeticMode_scalar::toString(SkString* str) const {
str->append("SkArithmeticMode_scalar: ");
for (int i = 0; i < 4; ++i) {
str->appendScalar(fK[i]);
if (i < 3) {
str->append(" ");
}
}
}
#endif
///////////////////////////////////////////////////////////////////////////////
static bool fitsInBits(SkScalar x, int bits) {
#ifdef SK_SCALAR_IS_FIXED
x = SkAbs32(x);
x += 1 << 7;
x >>= 8;
return x < (1 << (bits - 1));
#else
return SkScalarAbs(x) < (1 << (bits - 1));
#endif
}
#if 0 // UNUSED
static int32_t toDot8(SkScalar x) {
#ifdef SK_SCALAR_IS_FIXED
x += 1 << 7;
x >>= 8;
return x;
#else
return (int32_t)(x * 256);
#endif
}
#endif
SkXfermode* SkArithmeticMode::Create(SkScalar k1, SkScalar k2,
SkScalar k3, SkScalar k4) {
if (fitsInBits(k1, 8) && fitsInBits(k2, 16) &&
fitsInBits(k2, 16) && fitsInBits(k2, 24)) {
#if 0 // UNUSED
int32_t i1 = toDot8(k1);
int32_t i2 = toDot8(k2);
int32_t i3 = toDot8(k3);
int32_t i4 = toDot8(k4);
if (i1) {
return SkNEW_ARGS(SkArithmeticMode_quad, (i1, i2, i3, i4));
}
if (0 == i2) {
return SkNEW_ARGS(SkArithmeticMode_dst, (i3, i4));
}
if (0 == i3) {
return SkNEW_ARGS(SkArithmeticMode_src, (i2, i4));
}
return SkNEW_ARGS(SkArithmeticMode_linear, (i2, i3, i4));
#endif
}
return SkNEW_ARGS(SkArithmeticMode_scalar, (k1, k2, k3, k4));
}
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