sk_sp<SkData> encode_bitmap_for_png(SkBitmap bitmap) {
const int w = bitmap.width(),
h = bitmap.height();
// PNG wants unpremultiplied 8-bit RGBA pixels (16-bit could work fine too).
// We leave the gamma of these bytes unspecified, to continue the status quo,
// which we think generally is to interpret them as sRGB.
SkAutoTMalloc<uint32_t> rgba(w*h);
auto srgbColorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
if (bitmap. colorType() == kN32_SkColorType &&
bitmap.colorSpace() == srgbColorSpace.get()) {
// These are premul sRGB 8-bit pixels in SkPMColor order.
// We want unpremul sRGB 8-bit pixels in RGBA order. We'll get there via floats.
bitmap.lockPixels();
auto px = (const uint32_t*)bitmap.getPixels();
if (!px) {
return nullptr;
}
for (int i = 0; i < w*h; i++) {
Sk4f fs = Sk4f_fromS32(px[i]); // Convert up to linear floats.
#if defined(SK_PMCOLOR_IS_BGRA)
fs = SkNx_shuffle<2,1,0,3>(fs); // Shuffle to RGBA, if not there already.
#endif
float invA = 1.0f / fs[3];
fs = fs * Sk4f(invA, invA, invA, 1); // Unpremultiply.
rgba[i] = Sk4f_toS32(fs); // Pack down to sRGB bytes.
}
} else if (bitmap.colorType() == kRGBA_F16_SkColorType) {
// These are premul linear half-float pixels in RGBA order.
// We want unpremul sRGB 8-bit pixels in RGBA order. We'll get there via floats.
bitmap.lockPixels();
auto px = (const uint64_t*)bitmap.getPixels();
if (!px) {
return nullptr;
}
for (int i = 0; i < w*h; i++) {
// Convert up to linear floats.
Sk4f fs(SkHalfToFloat(static_cast<SkHalf>(px[i] >> (0 * 16))),
SkHalfToFloat(static_cast<SkHalf>(px[i] >> (1 * 16))),
SkHalfToFloat(static_cast<SkHalf>(px[i] >> (2 * 16))),
SkHalfToFloat(static_cast<SkHalf>(px[i] >> (3 * 16))));
fs = Sk4f::Max(0.0f, Sk4f::Min(fs, 1.0f)); // Clamp
float invA = 1.0f / fs[3];
fs = fs * Sk4f(invA, invA, invA, 1); // Unpremultiply.
rgba[i] = Sk4f_toS32(fs); // Pack down to sRGB bytes.
}
} else {
static void clear_srgb(const SkXfermode*, uint32_t dst[], const SkPM4f[],
int count, const SkAlpha aa[]) {
if (aa) {
for (int i = 0; i < count; ++i) {
if (aa[i]) {
Sk4f d = Sk4f_fromS32(dst[i]) * Sk4f((255 - aa[i]) * (1/255.0f));
dst[i] = Sk4f_toS32(d);
}
}
} else {
sk_memset32(dst, 0, count);
}
}
static void clear_srgb_n(const SkXfermode::PM4fState& state, uint32_t dst[], const SkPM4f[],
int count, const SkAlpha aa[]) {
if (aa) {
for (int i = 0; i < count; ++i) {
unsigned a = aa[i];
if (a) {
Sk4f d = Sk4f_fromS32(dst[i]) * Sk4f((255 - a) * (1/255.0f));
dst[i] = Sk4f_toS32(d);
}
}
} else {
sk_bzero(dst, count * sizeof(SkPMColor));
}
}
SkColor SkColor4f::toSkColor() const {
return Sk4f_toS32(swizzle_rb(Sk4f::Load(this->vec())));
}
static inline void brute_srcover_srgb_srgb_1(uint32_t* dst, uint32_t src) {
auto d = Sk4f_fromS32(*dst),
s = Sk4f_fromS32( src);
*dst = Sk4f_toS32(s + d * (1.0f - s[3]));
}
template <DstType D> uint32_t store_dst(const Sk4f& x4) {
return (D == kSRGB_Dst) ? Sk4f_toS32(x4) : Sk4f_toL32(x4);
}
