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author | senorblanco@chromium.org <senorblanco@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-05-26 20:03:03 +0000 |
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committer | senorblanco@chromium.org <senorblanco@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-05-26 20:03:03 +0000 |
commit | a4fc8d30896e63e7074ac06dbd7b13b00732f3c0 (patch) | |
tree | dafaca3fb8892930dce03ee8a6a7d266b46be18f /skia/sgl/SkGeometry.cpp | |
parent | 6131db47e71532f62aae3badcd34a82a64cb9f2a (diff) | |
download | chromium_src-a4fc8d30896e63e7074ac06dbd7b13b00732f3c0.zip chromium_src-a4fc8d30896e63e7074ac06dbd7b13b00732f3c0.tar.gz chromium_src-a4fc8d30896e63e7074ac06dbd7b13b00732f3c0.tar.bz2 |
Remove the remainder of the skia source code from the Chromium repo. It now lives over in third_party/skia (I only removed the headers in the first CL, since it was too unwieldy with all these deletes).
BUG=none
TEST=If it builds, you're happy.
R=dglazkov
Review URL: http://codereview.chromium.org/113827
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@16893 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'skia/sgl/SkGeometry.cpp')
-rw-r--r-- | skia/sgl/SkGeometry.cpp | 1072 |
1 files changed, 0 insertions, 1072 deletions
diff --git a/skia/sgl/SkGeometry.cpp b/skia/sgl/SkGeometry.cpp deleted file mode 100644 index 4f22e92..0000000 --- a/skia/sgl/SkGeometry.cpp +++ /dev/null @@ -1,1072 +0,0 @@ -/* libs/graphics/sgl/SkGeometry.cpp -** -** Copyright 2006, The Android Open Source Project -** -** Licensed under the Apache License, Version 2.0 (the "License"); -** you may not use this file except in compliance with the License. -** You may obtain a copy of the License at -** -** http://www.apache.org/licenses/LICENSE-2.0 -** -** Unless required by applicable law or agreed to in writing, software -** distributed under the License is distributed on an "AS IS" BASIS, -** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -** See the License for the specific language governing permissions and -** limitations under the License. -*/ - -#include "SkGeometry.h" -#include "Sk64.h" -#include "SkMatrix.h" - -/** If defined, this makes eval_quad and eval_cubic do more setup (sometimes - involving integer multiplies by 2 or 3, but fewer calls to SkScalarMul. - May also introduce overflow of fixed when we compute our setup. -*/ -#ifdef SK_SCALAR_IS_FIXED - #define DIRECT_EVAL_OF_POLYNOMIALS -#endif - -//////////////////////////////////////////////////////////////////////// - -#ifdef SK_SCALAR_IS_FIXED - static int is_not_monotonic(int a, int b, int c, int d) - { - return (((a - b) | (b - c) | (c - d)) & ((b - a) | (c - b) | (d - c))) >> 31; - } - - static int is_not_monotonic(int a, int b, int c) - { - return (((a - b) | (b - c)) & ((b - a) | (c - b))) >> 31; - } -#else - static int is_not_monotonic(float a, float b, float c) - { - float ab = a - b; - float bc = b - c; - if (ab < 0) - bc = -bc; - return ab == 0 || bc < 0; - } -#endif - -//////////////////////////////////////////////////////////////////////// - -static bool is_unit_interval(SkScalar x) -{ - return x > 0 && x < SK_Scalar1; -} - -static int valid_unit_divide(SkScalar numer, SkScalar denom, SkScalar* ratio) -{ - SkASSERT(ratio); - - if (numer < 0) - { - numer = -numer; - denom = -denom; - } - - if (denom == 0 || numer == 0 || numer >= denom) - return 0; - - SkScalar r = SkScalarDiv(numer, denom); - SkASSERT(r >= 0 && r < SK_Scalar1); - if (r == 0) // catch underflow if numer <<<< denom - return 0; - *ratio = r; - return 1; -} - -/** From Numerical Recipes in C. - - Q = -1/2 (B + sign(B) sqrt[B*B - 4*A*C]) - x1 = Q / A - x2 = C / Q -*/ -int SkFindUnitQuadRoots(SkScalar A, SkScalar B, SkScalar C, SkScalar roots[2]) -{ - SkASSERT(roots); - - if (A == 0) - return valid_unit_divide(-C, B, roots); - - SkScalar* r = roots; - -#ifdef SK_SCALAR_IS_FLOAT - float R = B*B - 4*A*C; - if (R < 0) // complex roots - return 0; - R = sk_float_sqrt(R); -#else - Sk64 RR, tmp; - - RR.setMul(B,B); - tmp.setMul(A,C); - tmp.shiftLeft(2); - RR.sub(tmp); - if (RR.isNeg()) - return 0; - SkFixed R = RR.getSqrt(); -#endif - - SkScalar Q = (B < 0) ? -(B-R)/2 : -(B+R)/2; - r += valid_unit_divide(Q, A, r); - r += valid_unit_divide(C, Q, r); - if (r - roots == 2) - { - if (roots[0] > roots[1]) - SkTSwap<SkScalar>(roots[0], roots[1]); - else if (roots[0] == roots[1]) // nearly-equal? - r -= 1; // skip the double root - } - return (int)(r - roots); -} - -#ifdef SK_SCALAR_IS_FIXED -/** Trim A/B/C down so that they are all <= 32bits - and then call SkFindUnitQuadRoots() -*/ -static int Sk64FindFixedQuadRoots(const Sk64& A, const Sk64& B, const Sk64& C, SkFixed roots[2]) -{ - int na = A.shiftToMake32(); - int nb = B.shiftToMake32(); - int nc = C.shiftToMake32(); - - int shift = SkMax32(na, SkMax32(nb, nc)); - SkASSERT(shift >= 0); - - return SkFindUnitQuadRoots(A.getShiftRight(shift), B.getShiftRight(shift), C.getShiftRight(shift), roots); -} -#endif - -///////////////////////////////////////////////////////////////////////////////////// -///////////////////////////////////////////////////////////////////////////////////// - -static SkScalar eval_quad(const SkScalar src[], SkScalar t) -{ - SkASSERT(src); - SkASSERT(t >= 0 && t <= SK_Scalar1); - -#ifdef DIRECT_EVAL_OF_POLYNOMIALS - SkScalar C = src[0]; - SkScalar A = src[4] - 2 * src[2] + C; - SkScalar B = 2 * (src[2] - C); - return SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C); -#else - SkScalar ab = SkScalarInterp(src[0], src[2], t); - SkScalar bc = SkScalarInterp(src[2], src[4], t); - return SkScalarInterp(ab, bc, t); -#endif -} - -static SkScalar eval_quad_derivative(const SkScalar src[], SkScalar t) -{ - SkScalar A = src[4] - 2 * src[2] + src[0]; - SkScalar B = src[2] - src[0]; - - return 2 * SkScalarMulAdd(A, t, B); -} - -static SkScalar eval_quad_derivative_at_half(const SkScalar src[]) -{ - SkScalar A = src[4] - 2 * src[2] + src[0]; - SkScalar B = src[2] - src[0]; - return A + 2 * B; -} - -void SkEvalQuadAt(const SkPoint src[3], SkScalar t, SkPoint* pt, SkVector* tangent) -{ - SkASSERT(src); - SkASSERT(t >= 0 && t <= SK_Scalar1); - - if (pt) - pt->set(eval_quad(&src[0].fX, t), eval_quad(&src[0].fY, t)); - if (tangent) - tangent->set(eval_quad_derivative(&src[0].fX, t), - eval_quad_derivative(&src[0].fY, t)); -} - -void SkEvalQuadAtHalf(const SkPoint src[3], SkPoint* pt, SkVector* tangent) -{ - SkASSERT(src); - - if (pt) - { - SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX); - SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY); - SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX); - SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY); - pt->set(SkScalarAve(x01, x12), SkScalarAve(y01, y12)); - } - if (tangent) - tangent->set(eval_quad_derivative_at_half(&src[0].fX), - eval_quad_derivative_at_half(&src[0].fY)); -} - -static void interp_quad_coords(const SkScalar* src, SkScalar* dst, SkScalar t) -{ - SkScalar ab = SkScalarInterp(src[0], src[2], t); - SkScalar bc = SkScalarInterp(src[2], src[4], t); - - dst[0] = src[0]; - dst[2] = ab; - dst[4] = SkScalarInterp(ab, bc, t); - dst[6] = bc; - dst[8] = src[4]; -} - -void SkChopQuadAt(const SkPoint src[3], SkPoint dst[5], SkScalar t) -{ - SkASSERT(t > 0 && t < SK_Scalar1); - - interp_quad_coords(&src[0].fX, &dst[0].fX, t); - interp_quad_coords(&src[0].fY, &dst[0].fY, t); -} - -void SkChopQuadAtHalf(const SkPoint src[3], SkPoint dst[5]) -{ - SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX); - SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY); - SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX); - SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY); - - dst[0] = src[0]; - dst[1].set(x01, y01); - dst[2].set(SkScalarAve(x01, x12), SkScalarAve(y01, y12)); - dst[3].set(x12, y12); - dst[4] = src[2]; -} - -/** Quad'(t) = At + B, where - A = 2(a - 2b + c) - B = 2(b - a) - Solve for t, only if it fits between 0 < t < 1 -*/ -int SkFindQuadExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar tValue[1]) -{ - /* At + B == 0 - t = -B / A - */ -#ifdef SK_SCALAR_IS_FIXED - return is_not_monotonic(a, b, c) && valid_unit_divide(a - b, a - b - b + c, tValue); -#else - return valid_unit_divide(a - b, a - b - b + c, tValue); -#endif -} - -static void flatten_double_quad_extrema(SkScalar coords[14]) -{ - coords[2] = coords[6] = coords[4]; -} - -static void force_quad_monotonic_in_y(SkPoint pts[3]) -{ - // zap pts[1].fY to the nearest value - SkScalar ab = SkScalarAbs(pts[0].fY - pts[1].fY); - SkScalar bc = SkScalarAbs(pts[1].fY - pts[2].fY); - pts[1].fY = ab < bc ? pts[0].fY : pts[2].fY; -} - -/* Returns 0 for 1 quad, and 1 for two quads, either way the answer is - stored in dst[]. Guarantees that the 1/2 quads will be monotonic. -*/ -int SkChopQuadAtYExtrema(const SkPoint src[3], SkPoint dst[5]) -{ - SkASSERT(src); - SkASSERT(dst); - -#if 0 - static bool once = true; - if (once) - { - once = false; - SkPoint s[3] = { 0, 26398, 0, 26331, 0, 20621428 }; - SkPoint d[6]; - - int n = SkChopQuadAtYExtrema(s, d); - SkDebugf("chop=%d, Y=[%x %x %x %x %x %x]\n", n, d[0].fY, d[1].fY, d[2].fY, d[3].fY, d[4].fY, d[5].fY); - } -#endif - - SkScalar a = src[0].fY; - SkScalar b = src[1].fY; - SkScalar c = src[2].fY; - - if (is_not_monotonic(a, b, c)) - { - SkScalar tValue; - if (valid_unit_divide(a - b, a - b - b + c, &tValue)) - { - SkChopQuadAt(src, dst, tValue); - flatten_double_quad_extrema(&dst[0].fY); - return 1; - } - // if we get here, we need to force dst to be monotonic, even though - // we couldn't compute a unit_divide value (probably underflow). - b = SkScalarAbs(a - b) < SkScalarAbs(b - c) ? a : c; - } - dst[0].set(src[0].fX, a); - dst[1].set(src[1].fX, b); - dst[2].set(src[2].fX, c); - return 0; -} - -// F(t) = a (1 - t) ^ 2 + 2 b t (1 - t) + c t ^ 2 -// F'(t) = 2 (b - a) + 2 (a - 2b + c) t -// F''(t) = 2 (a - 2b + c) -// -// A = 2 (b - a) -// B = 2 (a - 2b + c) -// -// Maximum curvature for a quadratic means solving -// Fx' Fx'' + Fy' Fy'' = 0 -// -// t = - (Ax Bx + Ay By) / (Bx ^ 2 + By ^ 2) -// -int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5]) -{ - SkScalar Ax = src[1].fX - src[0].fX; - SkScalar Ay = src[1].fY - src[0].fY; - SkScalar Bx = src[0].fX - src[1].fX - src[1].fX + src[2].fX; - SkScalar By = src[0].fY - src[1].fY - src[1].fY + src[2].fY; - SkScalar t = 0; // 0 means don't chop - -#ifdef SK_SCALAR_IS_FLOAT - (void)valid_unit_divide(-(Ax * Bx + Ay * By), Bx * Bx + By * By, &t); -#else - // !!! should I use SkFloat here? seems like it - Sk64 numer, denom, tmp; - - numer.setMul(Ax, -Bx); - tmp.setMul(Ay, -By); - numer.add(tmp); - - if (numer.isPos()) // do nothing if numer <= 0 - { - denom.setMul(Bx, Bx); - tmp.setMul(By, By); - denom.add(tmp); - SkASSERT(!denom.isNeg()); - if (numer < denom) - { - t = numer.getFixedDiv(denom); - SkASSERT(t >= 0 && t <= SK_Fixed1); // assert that we're numerically stable (ha!) - if ((unsigned)t >= SK_Fixed1) // runtime check for numerical stability - t = 0; // ignore the chop - } - } -#endif - - if (t == 0) - { - memcpy(dst, src, 3 * sizeof(SkPoint)); - return 1; - } - else - { - SkChopQuadAt(src, dst, t); - return 2; - } -} - -//////////////////////////////////////////////////////////////////////////////////////// -///// CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS // CUBICS ///// -//////////////////////////////////////////////////////////////////////////////////////// - -static void get_cubic_coeff(const SkScalar pt[], SkScalar coeff[4]) -{ - coeff[0] = pt[6] + 3*(pt[2] - pt[4]) - pt[0]; - coeff[1] = 3*(pt[4] - pt[2] - pt[2] + pt[0]); - coeff[2] = 3*(pt[2] - pt[0]); - coeff[3] = pt[0]; -} - -void SkGetCubicCoeff(const SkPoint pts[4], SkScalar cx[4], SkScalar cy[4]) -{ - SkASSERT(pts); - - if (cx) - get_cubic_coeff(&pts[0].fX, cx); - if (cy) - get_cubic_coeff(&pts[0].fY, cy); -} - -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 -} - -/** return At^2 + Bt + C -*/ -static SkScalar eval_quadratic(SkScalar A, SkScalar B, SkScalar C, SkScalar t) -{ - SkASSERT(t >= 0 && t <= SK_Scalar1); - - return SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C); -} - -static SkScalar eval_cubic_derivative(const SkScalar src[], SkScalar t) -{ - SkScalar A = src[6] + 3*(src[2] - src[4]) - src[0]; - SkScalar B = 2*(src[4] - 2 * src[2] + src[0]); - SkScalar C = src[2] - src[0]; - - return eval_quadratic(A, B, C, t); -} - -static SkScalar eval_cubic_2ndDerivative(const SkScalar src[], SkScalar t) -{ - SkScalar A = src[6] + 3*(src[2] - src[4]) - src[0]; - SkScalar B = src[4] - 2 * src[2] + src[0]; - - return SkScalarMulAdd(A, t, B); -} - -void SkEvalCubicAt(const SkPoint src[4], SkScalar t, SkPoint* loc, SkVector* tangent, SkVector* curvature) -{ - SkASSERT(src); - SkASSERT(t >= 0 && t <= SK_Scalar1); - - if (loc) - loc->set(eval_cubic(&src[0].fX, t), eval_cubic(&src[0].fY, t)); - if (tangent) - tangent->set(eval_cubic_derivative(&src[0].fX, t), - eval_cubic_derivative(&src[0].fY, t)); - if (curvature) - curvature->set(eval_cubic_2ndDerivative(&src[0].fX, t), - eval_cubic_2ndDerivative(&src[0].fY, t)); -} - -/** Cubic'(t) = At^2 + Bt + C, where - A = 3(-a + 3(b - c) + d) - B = 6(a - 2b + c) - C = 3(b - a) - Solve for t, keeping only those that fit betwee 0 < t < 1 -*/ -int SkFindCubicExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar d, SkScalar tValues[2]) -{ -#ifdef SK_SCALAR_IS_FIXED - if (!is_not_monotonic(a, b, c, d)) - return 0; -#endif - - // we divide A,B,C by 3 to simplify - SkScalar A = d - a + 3*(b - c); - SkScalar B = 2*(a - b - b + c); - SkScalar C = b - a; - - return SkFindUnitQuadRoots(A, B, C, tValues); -} - -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 SkChopCubicAt(const SkPoint src[4], SkPoint dst[7], SkScalar t) -{ - SkASSERT(t > 0 && t < SK_Scalar1); - - interp_cubic_coords(&src[0].fX, &dst[0].fX, t); - interp_cubic_coords(&src[0].fY, &dst[0].fY, t); -} - -void SkChopCubicAt(const SkPoint src[4], SkPoint dst[], const SkScalar tValues[], int roots) -{ -#ifdef SK_DEBUG - { - for (int i = 0; i < roots - 1; i++) - { - SkASSERT(is_unit_interval(tValues[i])); - SkASSERT(is_unit_interval(tValues[i+1])); - SkASSERT(tValues[i] < tValues[i+1]); - } - } -#endif - - if (dst) - { - if (roots == 0) // nothing to chop - memcpy(dst, src, 4*sizeof(SkPoint)); - else - { - SkScalar t = tValues[0]; - SkPoint tmp[4]; - - for (int i = 0; i < roots; i++) - { - SkChopCubicAt(src, dst, t); - if (i == roots - 1) - break; - - SkDEBUGCODE(int valid =) valid_unit_divide(tValues[i+1] - tValues[i], SK_Scalar1 - tValues[i], &t); - SkASSERT(valid); - - dst += 3; - memcpy(tmp, dst, 4 * sizeof(SkPoint)); - src = tmp; - } - } - } -} - -void SkChopCubicAtHalf(const SkPoint src[4], SkPoint dst[7]) -{ - SkScalar x01 = SkScalarAve(src[0].fX, src[1].fX); - SkScalar y01 = SkScalarAve(src[0].fY, src[1].fY); - SkScalar x12 = SkScalarAve(src[1].fX, src[2].fX); - SkScalar y12 = SkScalarAve(src[1].fY, src[2].fY); - SkScalar x23 = SkScalarAve(src[2].fX, src[3].fX); - SkScalar y23 = SkScalarAve(src[2].fY, src[3].fY); - - SkScalar x012 = SkScalarAve(x01, x12); - SkScalar y012 = SkScalarAve(y01, y12); - SkScalar x123 = SkScalarAve(x12, x23); - SkScalar y123 = SkScalarAve(y12, y23); - - dst[0] = src[0]; - dst[1].set(x01, y01); - dst[2].set(x012, y012); - dst[3].set(SkScalarAve(x012, x123), SkScalarAve(y012, y123)); - dst[4].set(x123, y123); - dst[5].set(x23, y23); - dst[6] = src[3]; -} - -static void flatten_double_cubic_extrema(SkScalar coords[14]) -{ - coords[4] = coords[8] = coords[6]; -} - -/** Given 4 points on a cubic bezier, chop it into 1, 2, 3 beziers such that - the resulting beziers are monotonic in Y. This is called by the scan converter. - Depending on what is returned, dst[] is treated as follows - 0 dst[0..3] is the original cubic - 1 dst[0..3] and dst[3..6] are the two new cubics - 2 dst[0..3], dst[3..6], dst[6..9] are the three new cubics - If dst == null, it is ignored and only the count is returned. -*/ -int SkChopCubicAtYExtrema(const SkPoint src[4], SkPoint dst[10]) -{ - SkScalar tValues[2]; - int roots = SkFindCubicExtrema(src[0].fY, src[1].fY, src[2].fY, src[3].fY, tValues); - - SkChopCubicAt(src, dst, tValues, roots); - if (dst && roots > 0) - { - // we do some cleanup to ensure our Y extrema are flat - flatten_double_cubic_extrema(&dst[0].fY); - if (roots == 2) - flatten_double_cubic_extrema(&dst[3].fY); - } - return roots; -} - -/** http://www.faculty.idc.ac.il/arik/quality/appendixA.html - - Inflection means that curvature is zero. - Curvature is [F' x F''] / [F'^3] - So we solve F'x X F''y - F'y X F''y == 0 - After some canceling of the cubic term, we get - A = b - a - B = c - 2b + a - C = d - 3c + 3b - a - (BxCy - ByCx)t^2 + (AxCy - AyCx)t + AxBy - AyBx == 0 -*/ -int SkFindCubicInflections(const SkPoint src[4], SkScalar tValues[]) -{ - SkScalar Ax = src[1].fX - src[0].fX; - SkScalar Ay = src[1].fY - src[0].fY; - SkScalar Bx = src[2].fX - 2 * src[1].fX + src[0].fX; - SkScalar By = src[2].fY - 2 * src[1].fY + src[0].fY; - SkScalar Cx = src[3].fX + 3 * (src[1].fX - src[2].fX) - src[0].fX; - SkScalar Cy = src[3].fY + 3 * (src[1].fY - src[2].fY) - src[0].fY; - int count; - -#ifdef SK_SCALAR_IS_FLOAT - count = SkFindUnitQuadRoots(Bx*Cy - By*Cx, Ax*Cy - Ay*Cx, Ax*By - Ay*Bx, tValues); -#else - Sk64 A, B, C, tmp; - - A.setMul(Bx, Cy); - tmp.setMul(By, Cx); - A.sub(tmp); - - B.setMul(Ax, Cy); - tmp.setMul(Ay, Cx); - B.sub(tmp); - - C.setMul(Ax, By); - tmp.setMul(Ay, Bx); - C.sub(tmp); - - count = Sk64FindFixedQuadRoots(A, B, C, tValues); -#endif - - return count; -} - -int SkChopCubicAtInflections(const SkPoint src[], SkPoint dst[10]) -{ - SkScalar tValues[2]; - int count = SkFindCubicInflections(src, tValues); - - if (dst) - { - if (count == 0) - memcpy(dst, src, 4 * sizeof(SkPoint)); - else - SkChopCubicAt(src, dst, tValues, count); - } - return count + 1; -} - -template <typename T> void bubble_sort(T array[], int count) -{ - for (int i = count - 1; i > 0; --i) - for (int j = i; j > 0; --j) - if (array[j] < array[j-1]) - { - T tmp(array[j]); - array[j] = array[j-1]; - array[j-1] = tmp; - } -} - -#include "SkFP.h" - -// newton refinement -#if 0 -static SkScalar refine_cubic_root(const SkFP coeff[4], SkScalar root) -{ - // x1 = x0 - f(t) / f'(t) - - SkFP T = SkScalarToFloat(root); - SkFP N, D; - - // f' = 3*coeff[0]*T^2 + 2*coeff[1]*T + coeff[2] - D = SkFPMul(SkFPMul(coeff[0], SkFPMul(T,T)), 3); - D = SkFPAdd(D, SkFPMulInt(SkFPMul(coeff[1], T), 2)); - D = SkFPAdd(D, coeff[2]); - - if (D == 0) - return root; - - // f = coeff[0]*T^3 + coeff[1]*T^2 + coeff[2]*T + coeff[3] - N = SkFPMul(SkFPMul(SkFPMul(T, T), T), coeff[0]); - N = SkFPAdd(N, SkFPMul(SkFPMul(T, T), coeff[1])); - N = SkFPAdd(N, SkFPMul(T, coeff[2])); - N = SkFPAdd(N, coeff[3]); - - if (N) - { - SkScalar delta = SkFPToScalar(SkFPDiv(N, D)); - - if (delta) - root -= delta; - } - return root; -} -#endif - -#if defined _WIN32 && _MSC_VER >= 1300 && defined SK_SCALAR_IS_FIXED // disable warning : unreachable code if building fixed point for windows desktop -#pragma warning ( disable : 4702 ) -#endif - -/* Solve coeff(t) == 0, returning the number of roots that - lie withing 0 < t < 1. - coeff[0]t^3 + coeff[1]t^2 + coeff[2]t + coeff[3] -*/ -static int solve_cubic_polynomial(const SkFP coeff[4], SkScalar tValues[3]) -{ -#ifndef SK_SCALAR_IS_FLOAT - return 0; // this is not yet implemented for software float -#endif - - if (SkScalarNearlyZero(coeff[0])) // we're just a quadratic - { - return SkFindUnitQuadRoots(coeff[1], coeff[2], coeff[3], tValues); - } - - SkFP a, b, c, Q, R; - - { - SkASSERT(coeff[0] != 0); - - SkFP inva = SkFPInvert(coeff[0]); - a = SkFPMul(coeff[1], inva); - b = SkFPMul(coeff[2], inva); - c = SkFPMul(coeff[3], inva); - } - Q = SkFPDivInt(SkFPSub(SkFPMul(a,a), SkFPMulInt(b, 3)), 9); -// R = (2*a*a*a - 9*a*b + 27*c) / 54; - R = SkFPMulInt(SkFPMul(SkFPMul(a, a), a), 2); - R = SkFPSub(R, SkFPMulInt(SkFPMul(a, b), 9)); - R = SkFPAdd(R, SkFPMulInt(c, 27)); - R = SkFPDivInt(R, 54); - - SkFP Q3 = SkFPMul(SkFPMul(Q, Q), Q); - SkFP R2MinusQ3 = SkFPSub(SkFPMul(R,R), Q3); - SkFP adiv3 = SkFPDivInt(a, 3); - - SkScalar* roots = tValues; - SkScalar r; - - if (SkFPLT(R2MinusQ3, 0)) // we have 3 real roots - { -#ifdef SK_SCALAR_IS_FLOAT - float theta = sk_float_acos(R / sk_float_sqrt(Q3)); - float neg2RootQ = -2 * sk_float_sqrt(Q); - - r = neg2RootQ * sk_float_cos(theta/3) - adiv3; - if (is_unit_interval(r)) - *roots++ = r; - - r = neg2RootQ * sk_float_cos((theta + 2*SK_ScalarPI)/3) - adiv3; - if (is_unit_interval(r)) - *roots++ = r; - - r = neg2RootQ * sk_float_cos((theta - 2*SK_ScalarPI)/3) - adiv3; - if (is_unit_interval(r)) - *roots++ = r; - - // now sort the roots - bubble_sort(tValues, (int)(roots - tValues)); -#endif - } - else // we have 1 real root - { - SkFP A = SkFPAdd(SkFPAbs(R), SkFPSqrt(R2MinusQ3)); - A = SkFPCubeRoot(A); - if (SkFPGT(R, 0)) - A = SkFPNeg(A); - - if (A != 0) - A = SkFPAdd(A, SkFPDiv(Q, A)); - r = SkFPToScalar(SkFPSub(A, adiv3)); - if (is_unit_interval(r)) - *roots++ = r; - } - - return (int)(roots - tValues); -} - -/* Looking for F' dot F'' == 0 - - A = b - a - B = c - 2b + a - C = d - 3c + 3b - a - - F' = 3Ct^2 + 6Bt + 3A - F'' = 6Ct + 6B - - F' dot F'' -> CCt^3 + 3BCt^2 + (2BB + CA)t + AB -*/ -static void formulate_F1DotF2(const SkScalar src[], SkFP coeff[4]) -{ - SkScalar a = src[2] - src[0]; - SkScalar b = src[4] - 2 * src[2] + src[0]; - SkScalar c = src[6] + 3 * (src[2] - src[4]) - src[0]; - - SkFP A = SkScalarToFP(a); - SkFP B = SkScalarToFP(b); - SkFP C = SkScalarToFP(c); - - coeff[0] = SkFPMul(C, C); - coeff[1] = SkFPMulInt(SkFPMul(B, C), 3); - coeff[2] = SkFPMulInt(SkFPMul(B, B), 2); - coeff[2] = SkFPAdd(coeff[2], SkFPMul(C, A)); - coeff[3] = SkFPMul(A, B); -} - -// EXPERIMENTAL: can set this to zero to accept all t-values 0 < t < 1 -//#define kMinTValueForChopping (SK_Scalar1 / 256) -#define kMinTValueForChopping 0 - -/* Looking for F' dot F'' == 0 - - A = b - a - B = c - 2b + a - C = d - 3c + 3b - a - - F' = 3Ct^2 + 6Bt + 3A - F'' = 6Ct + 6B - - F' dot F'' -> CCt^3 + 3BCt^2 + (2BB + CA)t + AB -*/ -int SkFindCubicMaxCurvature(const SkPoint src[4], SkScalar tValues[3]) -{ - SkFP coeffX[4], coeffY[4]; - int i; - - formulate_F1DotF2(&src[0].fX, coeffX); - formulate_F1DotF2(&src[0].fY, coeffY); - - for (i = 0; i < 4; i++) - coeffX[i] = SkFPAdd(coeffX[i],coeffY[i]); - - SkScalar t[3]; - int count = solve_cubic_polynomial(coeffX, t); - int maxCount = 0; - - // now remove extrema where the curvature is zero (mins) - // !!!! need a test for this !!!! - for (i = 0; i < count; i++) - { - // if (not_min_curvature()) - if (t[i] > kMinTValueForChopping && t[i] < SK_Scalar1 - kMinTValueForChopping) - tValues[maxCount++] = t[i]; - } - return maxCount; -} - -int SkChopCubicAtMaxCurvature(const SkPoint src[4], SkPoint dst[13], SkScalar tValues[3]) -{ - SkScalar t_storage[3]; - - if (tValues == NULL) - tValues = t_storage; - - int count = SkFindCubicMaxCurvature(src, tValues); - - if (dst) - { - if (count == 0) - memcpy(dst, src, 4 * sizeof(SkPoint)); - else - SkChopCubicAt(src, dst, tValues, count); - } - return count + 1; -} - -//////////////////////////////////////////////////////////////////////////////// - -/* Find t value for quadratic [a, b, c] = d. - Return 0 if there is no solution within [0, 1) -*/ -static SkScalar quad_solve(SkScalar a, SkScalar b, SkScalar c, SkScalar d) -{ - // At^2 + Bt + C = d - SkScalar A = a - 2 * b + c; - SkScalar B = 2 * (b - a); - SkScalar C = a - d; - - SkScalar roots[2]; - int count = SkFindUnitQuadRoots(A, B, C, roots); - - SkASSERT(count <= 1); - return count == 1 ? roots[0] : 0; -} - -/* given a quad-curve and a point (x,y), chop the quad at that point and return - the new quad's offCurve point. Should only return false if the computed pos - is the start of the curve (i.e. root == 0) -*/ -static bool quad_pt2OffCurve(const SkPoint quad[3], SkScalar x, SkScalar y, SkPoint* offCurve) -{ - const SkScalar* base; - SkScalar value; - - if (SkScalarAbs(x) < SkScalarAbs(y)) { - base = &quad[0].fX; - value = x; - } else { - base = &quad[0].fY; - value = y; - } - - // note: this returns 0 if it thinks value is out of range, meaning the - // root might return something outside of [0, 1) - SkScalar t = quad_solve(base[0], base[2], base[4], value); - - if (t > 0) - { - SkPoint tmp[5]; - SkChopQuadAt(quad, tmp, t); - *offCurve = tmp[1]; - return true; - } else { - /* t == 0 means either the value triggered a root outside of [0, 1) - For our purposes, we can ignore the <= 0 roots, but we want to - catch the >= 1 roots (which given our caller, will basically mean - a root of 1, give-or-take numerical instability). If we are in the - >= 1 case, return the existing offCurve point. - - The test below checks to see if we are close to the "end" of the - curve (near base[4]). Rather than specifying a tolerance, I just - check to see if value is on to the right/left of the middle point - (depending on the direction/sign of the end points). - */ - if ((base[0] < base[4] && value > base[2]) || - (base[0] > base[4] && value < base[2])) // should root have been 1 - { - *offCurve = quad[1]; - return true; - } - } - return false; -} - -static const SkPoint gQuadCirclePts[kSkBuildQuadArcStorage] = { - { SK_Scalar1, 0 }, - { SK_Scalar1, SK_ScalarTanPIOver8 }, - { SK_ScalarRoot2Over2, SK_ScalarRoot2Over2 }, - { SK_ScalarTanPIOver8, SK_Scalar1 }, - - { 0, SK_Scalar1 }, - { -SK_ScalarTanPIOver8, SK_Scalar1 }, - { -SK_ScalarRoot2Over2, SK_ScalarRoot2Over2 }, - { -SK_Scalar1, SK_ScalarTanPIOver8 }, - - { -SK_Scalar1, 0 }, - { -SK_Scalar1, -SK_ScalarTanPIOver8 }, - { -SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2 }, - { -SK_ScalarTanPIOver8, -SK_Scalar1 }, - - { 0, -SK_Scalar1 }, - { SK_ScalarTanPIOver8, -SK_Scalar1 }, - { SK_ScalarRoot2Over2, -SK_ScalarRoot2Over2 }, - { SK_Scalar1, -SK_ScalarTanPIOver8 }, - - { SK_Scalar1, 0 } -}; - -int SkBuildQuadArc(const SkVector& uStart, const SkVector& uStop, - SkRotationDirection dir, const SkMatrix* userMatrix, - SkPoint quadPoints[]) -{ - // rotate by x,y so that uStart is (1.0) - SkScalar x = SkPoint::DotProduct(uStart, uStop); - SkScalar y = SkPoint::CrossProduct(uStart, uStop); - - SkScalar absX = SkScalarAbs(x); - SkScalar absY = SkScalarAbs(y); - - int pointCount; - - // check for (effectively) coincident vectors - // this can happen if our angle is nearly 0 or nearly 180 (y == 0) - // ... we use the dot-prod to distinguish between 0 and 180 (x > 0) - if (absY <= SK_ScalarNearlyZero && x > 0 && - ((y >= 0 && kCW_SkRotationDirection == dir) || - (y <= 0 && kCCW_SkRotationDirection == dir))) { - - // just return the start-point - quadPoints[0].set(SK_Scalar1, 0); - pointCount = 1; - } else { - if (dir == kCCW_SkRotationDirection) - y = -y; - - // what octant (quadratic curve) is [xy] in? - int oct = 0; - bool sameSign = true; - - if (0 == y) - { - oct = 4; // 180 - SkASSERT(SkScalarAbs(x + SK_Scalar1) <= SK_ScalarNearlyZero); - } - else if (0 == x) - { - SkASSERT(absY - SK_Scalar1 <= SK_ScalarNearlyZero); - if (y > 0) - oct = 2; // 90 - else - oct = 6; // 270 - } - else - { - if (y < 0) - oct += 4; - if ((x < 0) != (y < 0)) - { - oct += 2; - sameSign = false; - } - if ((absX < absY) == sameSign) - oct += 1; - } - - int wholeCount = oct << 1; - memcpy(quadPoints, gQuadCirclePts, (wholeCount + 1) * sizeof(SkPoint)); - - const SkPoint* arc = &gQuadCirclePts[wholeCount]; - if (quad_pt2OffCurve(arc, x, y, &quadPoints[wholeCount + 1])) - { - quadPoints[wholeCount + 2].set(x, y); - wholeCount += 2; - } - pointCount = wholeCount + 1; - } - - // now handle counter-clockwise and the initial unitStart rotation - SkMatrix matrix; - matrix.setSinCos(uStart.fY, uStart.fX); - if (dir == kCCW_SkRotationDirection) { - matrix.preScale(SK_Scalar1, -SK_Scalar1); - } - if (userMatrix) { - matrix.postConcat(*userMatrix); - } - matrix.mapPoints(quadPoints, pointCount); - return pointCount; -} - - -///////////////////////////////////////////////////////////////////////////////////////// -///////////////////////////////////////////////////////////////////////////////////////// - -#ifdef SK_DEBUG - -void SkGeometry::UnitTest() -{ -#ifdef SK_SUPPORT_UNITTEST - SkPoint pts[3], dst[5]; - - pts[0].set(0, 0); - pts[1].set(100, 50); - pts[2].set(0, 100); - - int count = SkChopQuadAtMaxCurvature(pts, dst); - SkASSERT(count == 1 || count == 2); -#endif -} - -#endif - - |