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Diffstat (limited to 'libsgl/sgl/SkAlphaRuns.cpp')
| -rw-r--r-- | libsgl/sgl/SkAlphaRuns.cpp | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/libsgl/sgl/SkAlphaRuns.cpp b/libsgl/sgl/SkAlphaRuns.cpp new file mode 100644 index 0000000..46b0206 --- /dev/null +++ b/libsgl/sgl/SkAlphaRuns.cpp @@ -0,0 +1,185 @@ +/* libs/graphics/sgl/SkAlphaRuns.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 "SkAntiRun.h" + +void SkAlphaRuns::reset(int width) +{ + SkASSERT(width > 0); + + fRuns[0] = SkToS16(width); + fRuns[width] = 0; + fAlpha[0] = 0; + + SkDEBUGCODE(fWidth = width;) + SkDEBUGCODE(this->validate();) +} + +void SkAlphaRuns::Break(int16_t runs[], uint8_t alpha[], int x, int count) +{ + SkASSERT(count > 0 && x >= 0); + +// SkAlphaRuns::BreakAt(runs, alpha, x); +// SkAlphaRuns::BreakAt(&runs[x], &alpha[x], count); + + int16_t* next_runs = runs + x; + uint8_t* next_alpha = alpha + x; + + while (x > 0) + { + int n = runs[0]; + SkASSERT(n > 0); + + if (x < n) + { + alpha[x] = alpha[0]; + runs[0] = SkToS16(x); + runs[x] = SkToS16(n - x); + break; + } + runs += n; + alpha += n; + x -= n; + } + + runs = next_runs; + alpha = next_alpha; + x = count; + + for (;;) + { + int n = runs[0]; + SkASSERT(n > 0); + + if (x < n) + { + alpha[x] = alpha[0]; + runs[0] = SkToS16(x); + runs[x] = SkToS16(n - x); + break; + } + x -= n; + if (x <= 0) + break; + + runs += n; + alpha += n; + } +} + +void SkAlphaRuns::add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha, U8CPU maxValue) +{ + SkASSERT(middleCount >= 0); + SkASSERT(x >= 0 && x + (startAlpha != 0) + middleCount + (stopAlpha != 0) <= fWidth); + + int16_t* runs = fRuns; + uint8_t* alpha = fAlpha; + + if (startAlpha) + { + SkAlphaRuns::Break(runs, alpha, x, 1); + /* I should be able to just add alpha[x] + startAlpha. + However, if the trailing edge of the previous span and the leading + edge of the current span round to the same super-sampled x value, + I might overflow to 256 with this add, hence the funny subtract (crud). + */ + unsigned tmp = alpha[x] + startAlpha; + SkASSERT(tmp <= 256); + alpha[x] = SkToU8(tmp - (tmp >> 8)); // was (tmp >> 7), but that seems wrong if we're trying to catch 256 + + runs += x + 1; + alpha += x + 1; + x = 0; + SkDEBUGCODE(this->validate();) + } + if (middleCount) + { + SkAlphaRuns::Break(runs, alpha, x, middleCount); + alpha += x; + runs += x; + x = 0; + do { + alpha[0] = SkToU8(alpha[0] + maxValue); + int n = runs[0]; + SkASSERT(n <= middleCount); + alpha += n; + runs += n; + middleCount -= n; + } while (middleCount > 0); + SkDEBUGCODE(this->validate();) + } + if (stopAlpha) + { + SkAlphaRuns::Break(runs, alpha, x, 1); + alpha[x] = SkToU8(alpha[x] + stopAlpha); + SkDEBUGCODE(this->validate();) + } +} + +#ifdef SK_DEBUG + void SkAlphaRuns::assertValid(int y, int maxStep) const + { + int max = (y + 1) * maxStep - (y == maxStep - 1); + + const int16_t* runs = fRuns; + const uint8_t* alpha = fAlpha; + + while (*runs) + { + SkASSERT(*alpha <= max); + alpha += *runs; + runs += *runs; + } + } + + void SkAlphaRuns::dump() const + { + const int16_t* runs = fRuns; + const uint8_t* alpha = fAlpha; + + SkDebugf("Runs"); + while (*runs) + { + int n = *runs; + + SkDebugf(" %02x", *alpha); + if (n > 1) + SkDebugf(",%d", n); + alpha += n; + runs += n; + } + SkDebugf("\n"); + } + + void SkAlphaRuns::validate() const + { + SkASSERT(fWidth > 0); + + int count = 0; + const int16_t* runs = fRuns; + + while (*runs) + { + SkASSERT(*runs > 0); + count += *runs; + SkASSERT(count <= fWidth); + runs += *runs; + } + SkASSERT(count == fWidth); + } +#endif + |