gfx/skia/trunk/src/core/SkCubicClipper.cpp@129ffea94266 (annotated)
gfx/skia/trunk/src/core/SkCubicClipper.cpp
Sat, 03 Jan 2015 20:18:00 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Sat, 03 Jan 2015 20:18:00 +0100
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
- permissions
- -rw-r--r--
Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.
| michael@0 | 1 | |
| michael@0 | 2 | /* |
| michael@0 | 3 | * Copyright 2009 The Android Open Source Project |
| michael@0 | 4 | * |
| michael@0 | 5 | * Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 6 | * found in the LICENSE file. |
| michael@0 | 7 | */ |
| michael@0 | 8 | |
| michael@0 | 9 | |
| michael@0 | 10 | #include "SkCubicClipper.h" |
| michael@0 | 11 | #include "SkGeometry.h" |
| michael@0 | 12 | |
| michael@0 | 13 | SkCubicClipper::SkCubicClipper() { |
| michael@0 | 14 | fClip.setEmpty(); |
| michael@0 | 15 | } |
| michael@0 | 16 | |
| michael@0 | 17 | void SkCubicClipper::setClip(const SkIRect& clip) { |
| michael@0 | 18 | // conver to scalars, since that's where we'll see the points |
| michael@0 | 19 | fClip.set(clip); |
| michael@0 | 20 | } |
| michael@0 | 21 | |
| michael@0 | 22 | |
| michael@0 | 23 | static bool chopMonoCubicAtY(SkPoint pts[4], SkScalar y, SkScalar* t) { |
| michael@0 | 24 | SkScalar ycrv[4]; |
| michael@0 | 25 | ycrv[0] = pts[0].fY - y; |
| michael@0 | 26 | ycrv[1] = pts[1].fY - y; |
| michael@0 | 27 | ycrv[2] = pts[2].fY - y; |
| michael@0 | 28 | ycrv[3] = pts[3].fY - y; |
| michael@0 | 29 | |
| michael@0 | 30 | #ifdef NEWTON_RAPHSON // Quadratic convergence, typically <= 3 iterations. |
| michael@0 | 31 | // Initial guess. |
| michael@0 | 32 | // TODO(turk): Check for zero denominator? Shouldn't happen unless the curve |
| michael@0 | 33 | // is not only monotonic but degenerate. |
| michael@0 | 34 | SkScalar t1 = ycrv[0] / (ycrv[0] - ycrv[3]); |
| michael@0 | 35 | |
| michael@0 | 36 | // Newton's iterations. |
| michael@0 | 37 | const SkScalar tol = SK_Scalar1 / 16384; // This leaves 2 fixed noise bits. |
| michael@0 | 38 | SkScalar t0; |
| michael@0 | 39 | const int maxiters = 5; |
| michael@0 | 40 | int iters = 0; |
| michael@0 | 41 | bool converged; |
| michael@0 | 42 | do { |
| michael@0 | 43 | t0 = t1; |
| michael@0 | 44 | SkScalar y01 = SkScalarInterp(ycrv[0], ycrv[1], t0); |
| michael@0 | 45 | SkScalar y12 = SkScalarInterp(ycrv[1], ycrv[2], t0); |
| michael@0 | 46 | SkScalar y23 = SkScalarInterp(ycrv[2], ycrv[3], t0); |
| michael@0 | 47 | SkScalar y012 = SkScalarInterp(y01, y12, t0); |
| michael@0 | 48 | SkScalar y123 = SkScalarInterp(y12, y23, t0); |
| michael@0 | 49 | SkScalar y0123 = SkScalarInterp(y012, y123, t0); |
| michael@0 | 50 | SkScalar yder = (y123 - y012) * 3; |
| michael@0 | 51 | // TODO(turk): check for yder==0: horizontal. |
| michael@0 | 52 | t1 -= y0123 / yder; |
| michael@0 | 53 | converged = SkScalarAbs(t1 - t0) <= tol; // NaN-safe |
| michael@0 | 54 | ++iters; |
| michael@0 | 55 | } while (!converged && (iters < maxiters)); |
| michael@0 | 56 | *t = t1; // Return the result. |
| michael@0 | 57 | |
| michael@0 | 58 | // The result might be valid, even if outside of the range [0, 1], but |
| michael@0 | 59 | // we never evaluate a Bezier outside this interval, so we return false. |
| michael@0 | 60 | if (t1 < 0 || t1 > SK_Scalar1) |
| michael@0 | 61 | return false; // This shouldn't happen, but check anyway. |
| michael@0 | 62 | return converged; |
| michael@0 | 63 | |
| michael@0 | 64 | #else // BISECTION // Linear convergence, typically 16 iterations. |
| michael@0 | 65 | |
| michael@0 | 66 | // Check that the endpoints straddle zero. |
| michael@0 | 67 | SkScalar tNeg, tPos; // Negative and positive function parameters. |
| michael@0 | 68 | if (ycrv[0] < 0) { |
| michael@0 | 69 | if (ycrv[3] < 0) |
| michael@0 | 70 | return false; |
| michael@0 | 71 | tNeg = 0; |
| michael@0 | 72 | tPos = SK_Scalar1; |
| michael@0 | 73 | } else if (ycrv[0] > 0) { |
| michael@0 | 74 | if (ycrv[3] > 0) |
| michael@0 | 75 | return false; |
| michael@0 | 76 | tNeg = SK_Scalar1; |
| michael@0 | 77 | tPos = 0; |
| michael@0 | 78 | } else { |
| michael@0 | 79 | *t = 0; |
| michael@0 | 80 | return true; |
| michael@0 | 81 | } |
| michael@0 | 82 | |
| michael@0 | 83 | const SkScalar tol = SK_Scalar1 / 65536; // 1 for fixed, 1e-5 for float. |
| michael@0 | 84 | int iters = 0; |
| michael@0 | 85 | do { |
| michael@0 | 86 | SkScalar tMid = (tPos + tNeg) / 2; |
| michael@0 | 87 | SkScalar y01 = SkScalarInterp(ycrv[0], ycrv[1], tMid); |
| michael@0 | 88 | SkScalar y12 = SkScalarInterp(ycrv[1], ycrv[2], tMid); |
| michael@0 | 89 | SkScalar y23 = SkScalarInterp(ycrv[2], ycrv[3], tMid); |
| michael@0 | 90 | SkScalar y012 = SkScalarInterp(y01, y12, tMid); |
| michael@0 | 91 | SkScalar y123 = SkScalarInterp(y12, y23, tMid); |
| michael@0 | 92 | SkScalar y0123 = SkScalarInterp(y012, y123, tMid); |
| michael@0 | 93 | if (y0123 == 0) { |
| michael@0 | 94 | *t = tMid; |
| michael@0 | 95 | return true; |
| michael@0 | 96 | } |
| michael@0 | 97 | if (y0123 < 0) tNeg = tMid; |
| michael@0 | 98 | else tPos = tMid; |
| michael@0 | 99 | ++iters; |
| michael@0 | 100 | } while (!(SkScalarAbs(tPos - tNeg) <= tol)); // Nan-safe |
| michael@0 | 101 | |
| michael@0 | 102 | *t = (tNeg + tPos) / 2; |
| michael@0 | 103 | return true; |
| michael@0 | 104 | #endif // BISECTION |
| michael@0 | 105 | } |
| michael@0 | 106 | |
| michael@0 | 107 | |
| michael@0 | 108 | bool SkCubicClipper::clipCubic(const SkPoint srcPts[4], SkPoint dst[4]) { |
| michael@0 | 109 | bool reverse; |
| michael@0 | 110 | |
| michael@0 | 111 | // we need the data to be monotonically descending in Y |
| michael@0 | 112 | if (srcPts[0].fY > srcPts[3].fY) { |
| michael@0 | 113 | dst[0] = srcPts[3]; |
| michael@0 | 114 | dst[1] = srcPts[2]; |
| michael@0 | 115 | dst[2] = srcPts[1]; |
| michael@0 | 116 | dst[3] = srcPts[0]; |
| michael@0 | 117 | reverse = true; |
| michael@0 | 118 | } else { |
| michael@0 | 119 | memcpy(dst, srcPts, 4 * sizeof(SkPoint)); |
| michael@0 | 120 | reverse = false; |
| michael@0 | 121 | } |
| michael@0 | 122 | |
| michael@0 | 123 | // are we completely above or below |
| michael@0 | 124 | const SkScalar ctop = fClip.fTop; |
| michael@0 | 125 | const SkScalar cbot = fClip.fBottom; |
| michael@0 | 126 | if (dst[3].fY <= ctop || dst[0].fY >= cbot) { |
| michael@0 | 127 | return false; |
| michael@0 | 128 | } |
| michael@0 | 129 | |
| michael@0 | 130 | SkScalar t; |
| michael@0 | 131 | SkPoint tmp[7]; // for SkChopCubicAt |
| michael@0 | 132 | |
| michael@0 | 133 | // are we partially above |
| michael@0 | 134 | if (dst[0].fY < ctop && chopMonoCubicAtY(dst, ctop, &t)) { |
| michael@0 | 135 | SkChopCubicAt(dst, tmp, t); |
| michael@0 | 136 | dst[0] = tmp[3]; |
| michael@0 | 137 | dst[1] = tmp[4]; |
| michael@0 | 138 | dst[2] = tmp[5]; |
| michael@0 | 139 | } |
| michael@0 | 140 | |
| michael@0 | 141 | // are we partially below |
| michael@0 | 142 | if (dst[3].fY > cbot && chopMonoCubicAtY(dst, cbot, &t)) { |
| michael@0 | 143 | SkChopCubicAt(dst, tmp, t); |
| michael@0 | 144 | dst[1] = tmp[1]; |
| michael@0 | 145 | dst[2] = tmp[2]; |
| michael@0 | 146 | dst[3] = tmp[3]; |
| michael@0 | 147 | } |
| michael@0 | 148 | |
| michael@0 | 149 | if (reverse) { |
| michael@0 | 150 | SkTSwap<SkPoint>(dst[0], dst[3]); |
| michael@0 | 151 | SkTSwap<SkPoint>(dst[1], dst[2]); |
| michael@0 | 152 | } |
| michael@0 | 153 | return true; |
| michael@0 | 154 | } |
