/*
* Spits out a dummy gradient to test blur with shader on paint
*/
static sk_sp<SkShader> make_radial() {
SkPoint pts[2] = {
{ 0, 0 },
{ SkIntToScalar(100), SkIntToScalar(100) }
};
SkShader::TileMode tm = SkShader::kClamp_TileMode;
const SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, };
const SkScalar pos[] = { SK_Scalar1/4, SK_Scalar1*3/4 };
SkMatrix scale;
scale.setScale(0.5f, 0.5f);
scale.postTranslate(25.f, 25.f);
SkPoint center0, center1;
center0.set(SkScalarAve(pts[0].fX, pts[1].fX),
SkScalarAve(pts[0].fY, pts[1].fY));
center1.set(SkScalarInterp(pts[0].fX, pts[1].fX, SkIntToScalar(3)/5),
SkScalarInterp(pts[0].fY, pts[1].fY, SkIntToScalar(1)/4));
return SkGradientShader::MakeTwoPointConical(center1, (pts[1].fX - pts[0].fX) / 7,
center0, (pts[1].fX - pts[0].fX) / 2,
colors, pos, SK_ARRAY_COUNT(colors), tm,
0, &scale);
}
void TextArt::EnvelopeWarp::weight(const SkPoint src[], const SkPoint tSrc[], const SkPoint bSrc[], int count, const SkRect& srcBounds, SkPoint dst[])
{
for (int i = 0; i < count; i++)
{
SkScalar origY = src[i].fY;
SkScalar origX = src[i].fX;
dst[i].fX = bSrc[i].fX;
dst[i].fY = origY;
if (srcBounds.fBottom > 0)
origY -= srcBounds.fBottom;
SkScalar k1 = SkScalarAbs( SkScalarDiv(origY, srcBounds.height()) );
dst[i].fY = SkScalarInterp(bSrc[i].fY, tSrc[i].fY, k1);
if (xWeightingMode_ & XWeightingMode_Interpolating)
{ //in Interpolating mode calculate X as interpolation beween Top and Bottom
dst[i].fX = SkScalarInterp(bSrc[i].fX, tSrc[i].fX, k1);
}
}
}
static void interp_cubic_coords(const SkScalar* src, SkScalar* dst,
SkScalar t) {
SkScalar ab = SkScalarInterp(src[0], src[2], t);
SkScalar bc = SkScalarInterp(src[2], src[4], t);
SkScalar cd = SkScalarInterp(src[4], src[6], t);
SkScalar abc = SkScalarInterp(ab, bc, t);
SkScalar bcd = SkScalarInterp(bc, cd, t);
SkScalar abcd = SkScalarInterp(abc, bcd, t);
dst[0] = src[0];
dst[2] = ab;
dst[4] = abc;
dst[6] = abcd;
dst[8] = bcd;
dst[10] = cd;
dst[12] = src[6];
}
void onDrawContent(SkCanvas* canvas) override {
SkPaint paint;
paint.setTypeface(fTypeface);
paint.setAntiAlias(true);
paint.setFilterQuality(kMedium_SkFilterQuality);
paint.setTextSize(50);
// rough center of each glyph
static constexpr auto kMidX = 35;
static constexpr auto kMidY = 50;
canvas->clear(SK_ColorWHITE);
for (int i = 0; i < kNumChars; ++i) {
canvas->save();
double rot = SkScalarInterp(fChars[i].fStartRotation, fChars[i].fEndRotation,
fCurrTime/kDuration);
canvas->translate(fChars[i].fPosition.fX + kMidX, fChars[i].fPosition.fY - kMidY);
canvas->rotate(SkRadiansToDegrees(rot));
canvas->translate(-35,+50);
canvas->drawString(fChars[i].fChar, 0, 0, paint);
canvas->restore();
}
}
SkInterpolator::Result SkInterpolator::timeToValues(SkMSec time,
SkScalar values[]) const {
SkScalar T;
int index;
SkBool exact;
Result result = timeToT(time, &T, &index, &exact);
if (values) {
const SkScalar* nextSrc = &fValues[index * fElemCount];
if (exact) {
memcpy(values, nextSrc, fElemCount * sizeof(SkScalar));
} else {
SkASSERT(index > 0);
const SkScalar* prevSrc = nextSrc - fElemCount;
for (int i = fElemCount - 1; i >= 0; --i) {
values[i] = SkScalarInterp(prevSrc[i], nextSrc[i], T);
}
}
}
return result;
}
static SkScalar eval_cubic(const SkScalar src[], SkScalar t) {
SkASSERT(src);
SkASSERT(t >= 0 && t <= SK_Scalar1);
if (t == 0) {
return src[0];
}
#ifdef DIRECT_EVAL_OF_POLYNOMIALS
SkScalar D = src[0];
SkScalar A = src[6] + 3*(src[2] - src[4]) - D;
SkScalar B = 3*(src[4] - src[2] - src[2] + D);
SkScalar C = 3*(src[2] - D);
return SkScalarMulAdd(SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C), t, D);
#else
SkScalar ab = SkScalarInterp(src[0], src[2], t);
SkScalar bc = SkScalarInterp(src[2], src[4], t);
SkScalar cd = SkScalarInterp(src[4], src[6], t);
SkScalar abc = SkScalarInterp(ab, bc, t);
SkScalar bcd = SkScalarInterp(bc, cd, t);
return SkScalarInterp(abc, bcd, t);
#endif
}
static SkPoint SkPointInterp(const SkPoint& a, const SkPoint& b, SkScalar t) {
return SkMakePoint(SkScalarInterp(a.fX, b.fX, t),
SkScalarInterp(a.fY, b.fY, t));
}
static bool chopMonoCubicAtY(SkPoint pts[4], SkScalar y, SkScalar* t) {
SkScalar ycrv[4];
ycrv[0] = pts[0].fY - y;
ycrv[1] = pts[1].fY - y;
ycrv[2] = pts[2].fY - y;
ycrv[3] = pts[3].fY - y;
#ifdef NEWTON_RAPHSON // Quadratic convergence, typically <= 3 iterations.
// Initial guess.
// TODO(turk): Check for zero denominator? Shouldn't happen unless the curve
// is not only monotonic but degenerate.
#ifdef SK_SCALAR_IS_FLOAT
SkScalar t1 = ycrv[0] / (ycrv[0] - ycrv[3]);
#else // !SK_SCALAR_IS_FLOAT
SkScalar t1 = SkDivBits(ycrv[0], ycrv[0] - ycrv[3], 16);
#endif // !SK_SCALAR_IS_FLOAT
// Newton's iterations.
const SkScalar tol = SK_Scalar1 / 16384; // This leaves 2 fixed noise bits.
SkScalar t0;
const int maxiters = 5;
int iters = 0;
bool converged;
do {
t0 = t1;
SkScalar y01 = SkScalarInterp(ycrv[0], ycrv[1], t0);
SkScalar y12 = SkScalarInterp(ycrv[1], ycrv[2], t0);
SkScalar y23 = SkScalarInterp(ycrv[2], ycrv[3], t0);
SkScalar y012 = SkScalarInterp(y01, y12, t0);
SkScalar y123 = SkScalarInterp(y12, y23, t0);
SkScalar y0123 = SkScalarInterp(y012, y123, t0);
SkScalar yder = (y123 - y012) * 3;
// TODO(turk): check for yder==0: horizontal.
#ifdef SK_SCALAR_IS_FLOAT
t1 -= y0123 / yder;
#else // !SK_SCALAR_IS_FLOAT
t1 -= SkDivBits(y0123, yder, 16);
#endif // !SK_SCALAR_IS_FLOAT
converged = SkScalarAbs(t1 - t0) <= tol; // NaN-safe
++iters;
} while (!converged && (iters < maxiters));
*t = t1; // Return the result.
// The result might be valid, even if outside of the range [0, 1], but
// we never evaluate a Bezier outside this interval, so we return false.
if (t1 < 0 || t1 > SK_Scalar1)
return false; // This shouldn't happen, but check anyway.
return converged;
#else // BISECTION // Linear convergence, typically 16 iterations.
// Check that the endpoints straddle zero.
SkScalar tNeg, tPos; // Negative and positive function parameters.
if (ycrv[0] < 0) {
if (ycrv[3] < 0)
return false;
tNeg = 0;
tPos = SK_Scalar1;
} else if (ycrv[0] > 0) {
if (ycrv[3] > 0)
return false;
tNeg = SK_Scalar1;
tPos = 0;
} else {
*t = 0;
return true;
}
const SkScalar tol = SK_Scalar1 / 65536; // 1 for fixed, 1e-5 for float.
int iters = 0;
do {
SkScalar tMid = (tPos + tNeg) / 2;
SkScalar y01 = SkScalarInterp(ycrv[0], ycrv[1], tMid);
SkScalar y12 = SkScalarInterp(ycrv[1], ycrv[2], tMid);
SkScalar y23 = SkScalarInterp(ycrv[2], ycrv[3], tMid);
SkScalar y012 = SkScalarInterp(y01, y12, tMid);
SkScalar y123 = SkScalarInterp(y12, y23, tMid);
SkScalar y0123 = SkScalarInterp(y012, y123, tMid);
if (y0123 == 0) {
*t = tMid;
return true;
}
if (y0123 < 0) tNeg = tMid;
else tPos = tMid;
++iters;
} while (!(SkScalarAbs(tPos - tNeg) <= tol)); // Nan-safe
*t = (tNeg + tPos) / 2;
return true;
#endif // BISECTION
}
