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/* libs/graphics/sgl/SkAntiRun.h
**
** 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.
*/
#ifndef SkAntiRun_DEFINED
#define SkAntiRun_DEFINED
#include "SkBlitter.h"
inline int sk_make_nonzero_neg_one(int x)
{
return (x | -x) >> 31;
}
#if 0
template <int kShift> class SkAntiRun {
static uint8_t coverage_to_alpha(int aa)
{
aa <<= 8 - 2*kShift;
aa -= aa >> (8 - kShift - 1);
return SkToU8(aa);
}
public:
void set(int start, int stop)
{
SkASSERT(start >= 0 && stop > start);
#if 1
int fb = start & kMask;
int fe = stop & kMask;
int n = (stop >> kShift) - (start >> kShift) - 1;
if (n < 0)
{
fb = fe - fb;
n = 0;
fe = 0;
}
else
{
if (fb == 0)
n += 1;
else
fb = (1 << kShift) - fb;
}
fStartAlpha = coverage_to_alpha(fb);
fMiddleCount = n;
fStopAlpha = coverage_to_alpha(fe);
#else
int x0 = start >> kShift;
int x1 = (stop - 1) >> kShift;
int middle = x1 - x0;
int aa;
if (middle == 0)
{
aa = stop - start;
aa <<= 8 - 2*kShift;
aa -= aa >> (8 - kShift - 1);
SkASSERT(aa > 0 && aa < kMax);
fStartAlpha = SkToU8(aa);
fMiddleCount = 0;
fStopAlpha = 0;
}
else
{
int aa = start & kMask;
aa <<= 8 - 2*kShift;
aa -= aa >> (8 - kShift - 1);
SkASSERT(aa >= 0 && aa < kMax);
if (aa)
fStartAlpha = SkToU8(kMax - aa);
else
{
fStartAlpha = 0;
middle += 1;
}
aa = stop & kMask;
aa <<= 8 - 2*kShift;
aa -= aa >> (8 - kShift - 1);
SkASSERT(aa >= 0 && aa < kMax);
middle += sk_make_nonzero_neg_one(aa);
fStopAlpha = SkToU8(aa);
fMiddleCount = middle;
}
SkASSERT(fStartAlpha < kMax);
SkASSERT(fStopAlpha < kMax);
#endif
}
void blit(int x, int y, SkBlitter* blitter)
{
int16_t runs[2];
runs[0] = 1;
runs[1] = 0;
if (fStartAlpha)
{
blitter->blitAntiH(x, y, &fStartAlpha, runs);
x += 1;
}
if (fMiddleCount)
{
blitter->blitH(x, y, fMiddleCount);
x += fMiddleCount;
}
if (fStopAlpha)
blitter->blitAntiH(x, y, &fStopAlpha, runs);
}
uint8_t getStartAlpha() const { return fStartAlpha; }
int getMiddleCount() const { return fMiddleCount; }
uint8_t getStopAlpha() const { return fStopAlpha; }
private:
uint8_t fStartAlpha, fStopAlpha;
int fMiddleCount;
enum {
kMask = (1 << kShift) - 1,
kMax = (1 << (8 - kShift)) - 1
};
};
#endif
////////////////////////////////////////////////////////////////////////////////////
class SkAlphaRuns {
public:
int16_t* fRuns;
uint8_t* fAlpha;
bool empty() const
{
SkASSERT(fRuns[0] > 0);
return fAlpha[0] == 0 && fRuns[fRuns[0]] == 0;
}
void reset(int width);
void add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha, U8CPU maxValue);
SkDEBUGCODE(void assertValid(int y, int maxStep) const;)
SkDEBUGCODE(void dump() const;)
static void Break(int16_t runs[], uint8_t alpha[], int x, int count);
static void BreakAt(int16_t runs[], uint8_t alpha[], int 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;
}
}
private:
SkDEBUGCODE(int fWidth;)
SkDEBUGCODE(void validate() const;)
};
#endif
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