The Tor Browser / file comparison
comparison: gfx/skia/trunk/src/effects/gradients/SkClampRange.cpp
gfx/skia/trunk/src/effects/gradients/SkClampRange.cpp
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:da3db4dd9268 |
|---|---|
| 1 | |
| 2 /* | |
| 3 * Copyright 2011 Google Inc. | |
| 4 * | |
| 5 * Use of this source code is governed by a BSD-style license that can be | |
| 6 * found in the LICENSE file. | |
| 7 */ | |
| 8 | |
| 9 | |
| 10 #include "SkClampRange.h" | |
| 11 | |
| 12 /* | |
| 13 * returns [0..count] for the number of steps (<= count) for which x0 <= edge | |
| 14 * given each step is followed by x0 += dx | |
| 15 */ | |
| 16 static int chop(int64_t x0, SkFixed edge, int64_t x1, int64_t dx, int count) { | |
| 17 SkASSERT(dx > 0); | |
| 18 SkASSERT(count >= 0); | |
| 19 | |
| 20 if (x0 >= edge) { | |
| 21 return 0; | |
| 22 } | |
| 23 if (x1 <= edge) { | |
| 24 return count; | |
| 25 } | |
| 26 int64_t n = (edge - x0 + dx - 1) / dx; | |
| 27 SkASSERT(n >= 0); | |
| 28 SkASSERT(n <= count); | |
| 29 return (int)n; | |
| 30 } | |
| 31 | |
| 32 static bool overflows_fixed(int64_t x) { | |
| 33 return x < -SK_FixedMax || x > SK_FixedMax; | |
| 34 } | |
| 35 | |
| 36 void SkClampRange::initFor1(SkFixed fx) { | |
| 37 fCount0 = fCount1 = fCount2 = 0; | |
| 38 if (fx <= 0) { | |
| 39 fCount0 = 1; | |
| 40 } else if (fx < 0xFFFF) { | |
| 41 fCount1 = 1; | |
| 42 fFx1 = fx; | |
| 43 } else { | |
| 44 fCount2 = 1; | |
| 45 } | |
| 46 } | |
| 47 | |
| 48 void SkClampRange::init(SkFixed fx0, SkFixed dx0, int count, int v0, int v1) { | |
| 49 SkASSERT(count > 0); | |
| 50 | |
| 51 fV0 = v0; | |
| 52 fV1 = v1; | |
| 53 fOverflowed = false; | |
| 54 | |
| 55 // special case 1 == count, as it is slightly common for skia | |
| 56 // and avoids us ever calling divide or 64bit multiply | |
| 57 if (1 == count) { | |
| 58 this->initFor1(fx0); | |
| 59 return; | |
| 60 } | |
| 61 | |
| 62 int64_t fx = fx0; | |
| 63 int64_t dx = dx0; | |
| 64 // start with ex equal to the last computed value | |
| 65 int64_t ex = fx + (count - 1) * dx; | |
| 66 fOverflowed = overflows_fixed(ex); | |
| 67 | |
| 68 if ((uint64_t)(fx | ex) <= 0xFFFF) { | |
| 69 fCount0 = fCount2 = 0; | |
| 70 fCount1 = count; | |
| 71 fFx1 = fx0; | |
| 72 return; | |
| 73 } | |
| 74 if (fx <= 0 && ex <= 0) { | |
| 75 fCount1 = fCount2 = 0; | |
| 76 fCount0 = count; | |
| 77 return; | |
| 78 } | |
| 79 if (fx >= 0xFFFF && ex >= 0xFFFF) { | |
| 80 fCount0 = fCount1 = 0; | |
| 81 fCount2 = count; | |
| 82 return; | |
| 83 } | |
| 84 | |
| 85 int extraCount = 0; | |
| 86 | |
| 87 // now make ex be 1 past the last computed value | |
| 88 ex += dx; | |
| 89 fOverflowed = overflows_fixed(ex); | |
| 90 // now check for over/under flow | |
| 91 if (fOverflowed) { | |
| 92 int originalCount = count; | |
| 93 int64_t ccount; | |
| 94 bool swap = dx < 0; | |
| 95 if (swap) { | |
| 96 dx = -dx; | |
| 97 fx = -fx; | |
| 98 } | |
| 99 ccount = (SK_FixedMax - fx + dx - 1) / dx; | |
| 100 if (swap) { | |
| 101 dx = -dx; | |
| 102 fx = -fx; | |
| 103 } | |
| 104 SkASSERT(ccount > 0 && ccount <= SK_FixedMax); | |
| 105 | |
| 106 count = (int)ccount; | |
| 107 if (0 == count) { | |
| 108 this->initFor1(fx0); | |
| 109 if (dx > 0) { | |
| 110 fCount2 += originalCount - 1; | |
| 111 } else { | |
| 112 fCount0 += originalCount - 1; | |
| 113 } | |
| 114 return; | |
| 115 } | |
| 116 extraCount = originalCount - count; | |
| 117 ex = fx + dx * count; | |
| 118 } | |
| 119 | |
| 120 bool doSwap = dx < 0; | |
| 121 | |
| 122 if (doSwap) { | |
| 123 ex -= dx; | |
| 124 fx -= dx; | |
| 125 SkTSwap(fx, ex); | |
| 126 dx = -dx; | |
| 127 } | |
| 128 | |
| 129 | |
| 130 fCount0 = chop(fx, 0, ex, dx, count); | |
| 131 count -= fCount0; | |
| 132 fx += fCount0 * dx; | |
| 133 SkASSERT(fx >= 0); | |
| 134 SkASSERT(fCount0 == 0 || (fx - dx) < 0); | |
| 135 fCount1 = chop(fx, 0xFFFF, ex, dx, count); | |
| 136 count -= fCount1; | |
| 137 fCount2 = count; | |
| 138 | |
| 139 #ifdef SK_DEBUG | |
| 140 fx += fCount1 * dx; | |
| 141 SkASSERT(fx <= ex); | |
| 142 if (fCount2 > 0) { | |
| 143 SkASSERT(fx >= 0xFFFF); | |
| 144 if (fCount1 > 0) { | |
| 145 SkASSERT(fx - dx < 0xFFFF); | |
| 146 } | |
| 147 } | |
| 148 #endif | |
| 149 | |
| 150 if (doSwap) { | |
| 151 SkTSwap(fCount0, fCount2); | |
| 152 SkTSwap(fV0, fV1); | |
| 153 dx = -dx; | |
| 154 } | |
| 155 | |
| 156 if (fCount1 > 0) { | |
| 157 fFx1 = fx0 + fCount0 * (int)dx; | |
| 158 } | |
| 159 | |
| 160 if (dx > 0) { | |
| 161 fCount2 += extraCount; | |
| 162 } else { | |
| 163 fCount0 += extraCount; | |
| 164 } | |
| 165 } |
