/* scale here is 1/rate */
static int cdf_dgamma (lua_State *L) {
/* stack should contain x, shape and opt. scale */
lua_Number x = luaL_checknumber(L, 1);
lua_Number shape = luaL_checknumber(L, 2);
lua_Number scale = luaL_optnumber(L, 3, 1);
lua_Number d;
check_gamma(L, 1, x, shape, scale);
d = x * scale;
d = exp(shape*log(d)-d-dlngam(&shape))/x;
lua_pushnumber(L, d);
return 1;
}
static int cdf_pgamma (lua_State *L) {
/* stack should contain x, shape and opt. scale */
lua_Number x = luaL_checknumber(L, 1);
lua_Number shape = luaL_checknumber(L, 2);
lua_Number scale = luaL_optnumber(L, 3, 1);
lua_Number p, q, bound;
int which = 1;
int status;
check_gamma(L, 1, x, shape, scale);
cdfgam(&which, &p, &q, &x, &shape, &scale, &status, &bound);
check_status(status, bound);
lua_pushnumber(L, p);
return 1;
}
static int cdf_qgamma (lua_State *L) {
/* stack should contain p, shape and opt. scale */
lua_Number p = luaL_checknumber(L, 1);
lua_Number shape = luaL_checknumber(L, 2);
lua_Number scale = luaL_optnumber(L, 3, 1);
lua_Number x;
check_gamma(L, 2, p, shape, scale);
if (p==0 || p==1) x = (p==0) ? 0 : HUGE_VAL;
else {
lua_Number q = 1-p;
lua_Number bound;
int which = 2;
int status;
cdfgam(&which, &p, &q, &x, &shape, &scale, &status, &bound);
check_status(status, bound);
}
lua_pushnumber(L, x);
return 1;
}
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ApplyGamma, reporter, ctxInfo) {
GrContext* context = ctxInfo.grContext();
static const int kW = 256;
static const int kH = 256;
static const size_t kRowBytes = sizeof(uint32_t) * kW;
GrSurfaceDesc baseDesc;
baseDesc.fConfig = kRGBA_8888_GrPixelConfig;
baseDesc.fWidth = kW;
baseDesc.fHeight = kH;
const SkImageInfo ii = SkImageInfo::MakeN32Premul(kW, kH);
SkAutoTMalloc<uint32_t> srcPixels(kW * kH);
for (int y = 0; y < kH; ++y) {
for (int x = 0; x < kW; ++x) {
srcPixels.get()[y*kW+x] = SkPreMultiplyARGB(x, y, x, 0xFF);
}
}
SkBitmap bm;
bm.installPixels(ii, srcPixels.get(), kRowBytes);
SkAutoTMalloc<uint32_t> read(kW * kH);
// We allow more error on GPUs with lower precision shader variables.
float error = context->caps()->shaderCaps()->floatPrecisionVaries() ? 1.2f : 0.5f;
for (auto toSRGB : { false, true }) {
sk_sp<SkSurface> dst(SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, ii));
if (!dst) {
ERRORF(reporter, "Could not create surfaces for copy surface test.");
continue;
}
SkCanvas* dstCanvas = dst->getCanvas();
dstCanvas->clear(SK_ColorRED);
dstCanvas->flush();
SkPaint gammaPaint;
gammaPaint.setBlendMode(SkBlendMode::kSrc);
gammaPaint.setColorFilter(toSRGB ? SkColorFilter::MakeLinearToSRGBGamma()
: SkColorFilter::MakeSRGBToLinearGamma());
dstCanvas->drawBitmap(bm, 0, 0, &gammaPaint);
dstCanvas->flush();
sk_memset32(read.get(), 0, kW * kH);
if (!dstCanvas->readPixels(ii, read.get(), kRowBytes, 0, 0)) {
ERRORF(reporter, "Error calling readPixels");
continue;
}
bool abort = false;
// Validate that pixels were copied/transformed correctly.
for (int y = 0; y < kH && !abort; ++y) {
for (int x = 0; x < kW && !abort; ++x) {
uint32_t r = read.get()[y * kW + x];
uint32_t s = srcPixels.get()[y * kW + x];
uint32_t expected;
if (!check_gamma(s, r, toSRGB, error, &expected)) {
ERRORF(reporter, "Expected dst %d,%d to contain 0x%08x "
"from src 0x%08x and mode %s. Got %08x", x, y, expected, s,
toSRGB ? "ToSRGB" : "ToLinear", r);
abort = true;
break;
}
}
}
}
}