SkColor SkHSVToColor(U8CPU a, const SkScalar hsv[3]) {
SkASSERT(hsv);
U8CPU s = SkUnitScalarClampToByte(hsv[1]);
U8CPU v = SkUnitScalarClampToByte(hsv[2]);
if (0 == s) { // shade of gray
return SkColorSetARGB(a, v, v, v);
}
SkFixed hx = (hsv[0] < 0 || hsv[0] >= SkIntToScalar(360)) ? 0 : SkScalarToFixed(hsv[0]/60);
SkFixed f = hx & 0xFFFF;
unsigned v_scale = SkAlpha255To256(v);
unsigned p = SkAlphaMul(255 - s, v_scale);
unsigned q = SkAlphaMul(255 - (s * f >> 16), v_scale);
unsigned t = SkAlphaMul(255 - (s * (SK_Fixed1 - f) >> 16), v_scale);
unsigned r, g, b;
SkASSERT((unsigned)(hx >> 16) < 6);
switch (hx >> 16) {
case 0: r = v; g = t; b = p; break;
case 1: r = q; g = v; b = p; break;
case 2: r = p; g = v; b = t; break;
case 3: r = p; g = q; b = v; break;
case 4: r = t; g = p; b = v; break;
default: r = v; g = p; b = q; break;
}
return SkColorSetARGB(a, r, g, b);
}
static uint8_t* create_half_plane_profile(int profileWidth) {
SkASSERT(!(profileWidth & 0x1));
// The full kernel is 6 sigmas wide.
float sigma = profileWidth / 6.f;
int halfKernelSize = profileWidth / 2;
SkAutoTArray<float> halfKernel(halfKernelSize);
uint8_t* profile = new uint8_t[profileWidth];
// The half kernel should sum to 0.5.
const float tot = 2.f * make_unnormalized_half_kernel(halfKernel.get(), halfKernelSize, sigma);
float sum = 0.f;
// Populate the profile from the right edge to the middle.
for (int i = 0; i < halfKernelSize; ++i) {
halfKernel[halfKernelSize - i - 1] /= tot;
sum += halfKernel[halfKernelSize - i - 1];
profile[profileWidth - i - 1] = SkUnitScalarClampToByte(sum);
}
// Populate the profile from the middle to the left edge (by flipping the half kernel and
// continuing the summation).
for (int i = 0; i < halfKernelSize; ++i) {
sum += halfKernel[i];
profile[halfKernelSize - i - 1] = SkUnitScalarClampToByte(sum);
}
// Ensure tail goes to 0.
profile[profileWidth - 1] = 0;
return profile;
}
sk_sp<SkMaskFilter> SkBlurMaskFilter::MakeEmboss(SkScalar blurSigma, const SkScalar direction[3],
SkScalar ambient, SkScalar specular) {
if (direction == nullptr) {
return nullptr;
}
SkEmbossMaskFilter::Light light;
memcpy(light.fDirection, direction, sizeof(light.fDirection));
// ambient should be 0...1 as a scalar
light.fAmbient = SkUnitScalarClampToByte(ambient);
// specular should be 0..15.99 as a scalar
static const SkScalar kSpecularMultiplier = SkIntToScalar(255) / 16;
light.fSpecular = static_cast<U8CPU>(SkScalarPin(specular, 0, 16) * kSpecularMultiplier + 0.5);
return SkEmbossMaskFilter::Make(blurSigma, light);
}
// Apply the half-kernel at 't' away from the center of the circle
static uint8_t eval_at(float t, float halfWidth, float* halfKernel, int kernelWH) {
SkASSERT(!(kernelWH & 1));
const float kernelOff = (kernelWH-1)/2.0f;
float acc = 0;
for (int y = 0; y < kernelWH/2; ++y) {
if (kernelOff-y > halfWidth+0.5f) {
// All disk() samples in this row will be 0.0f
continue;
}
for (int x = 0; x < kernelWH; ++x) {
float image = disk(t - kernelOff + x, -kernelOff + y, halfWidth);
float kernel = halfKernel[y*kernelWH+x];
acc += kernel * image;
}
}
return SkUnitScalarClampToByte(acc);
}
// Apply a Gaussian at point (evalX, 0) to a circle centered at the origin with radius circleR.
// This relies on having a half kernel computed for the Gaussian and a table of applications of
// the half kernel in y to columns at (evalX - halfKernel, evalX - halfKernel + 1, ..., evalX +
// halfKernel) passed in as yKernelEvaluations.
static uint8_t eval_at(float evalX, float circleR, const float* halfKernel, int halfKernelSize,
const float* yKernelEvaluations) {
float acc = 0;
float x = evalX - halfKernelSize;
for (int i = 0; i < halfKernelSize; ++i, x += 1.f) {
if (x < -circleR || x > circleR) {
continue;
}
float verticalEval = yKernelEvaluations[i];
acc += verticalEval * halfKernel[halfKernelSize - i - 1];
}
for (int i = 0; i < halfKernelSize; ++i, x += 1.f) {
if (x < -circleR || x > circleR) {
continue;
}
float verticalEval = yKernelEvaluations[i + halfKernelSize];
acc += verticalEval * halfKernel[i];
}
// Since we applied a half kernel in y we multiply acc by 2 (the circle is symmetric about
// the x axis).
return SkUnitScalarClampToByte(2.f * acc);
}
