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/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkRegionPriv.h"
#include "SkBlitter.h"
#include "SkScan.h"
#include "SkTSort.h"
#include "SkTDArray.h"
#include "SkPath.h"
// The rgnbuilder caller *seems* to pass short counts, possible often seens early failure, so
// we may not want to promote this to a "std" routine just yet.
static bool sk_memeq32(const int32_t* SK_RESTRICT a, const int32_t* SK_RESTRICT b, int count) {
for (int i = 0; i < count; ++i) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
class SkRgnBuilder : public SkBlitter {
public:
SkRgnBuilder();
~SkRgnBuilder() override;
// returns true if it could allocate the working storage needed
bool init(int maxHeight, int maxTransitions, bool pathIsInverse);
void done() {
if (fCurrScanline != nullptr) {
fCurrScanline->fXCount = (SkRegion::RunType)((int)(fCurrXPtr - fCurrScanline->firstX()));
if (!this->collapsWithPrev()) { // flush the last line
fCurrScanline = fCurrScanline->nextScanline();
}
}
}
int computeRunCount() const;
void copyToRect(SkIRect*) const;
void copyToRgn(SkRegion::RunType runs[]) const;
void blitH(int x, int y, int width) override;
void blitAntiH(int x, int y, const SkAlpha antialias[], const int16_t runs[]) override {
SkDEBUGFAIL("blitAntiH not implemented");
}
#ifdef SK_DEBUG
void dump() const {
SkDebugf("SkRgnBuilder: Top = %d\n", fTop);
const Scanline* line = (Scanline*)fStorage;
while (line < fCurrScanline) {
SkDebugf("SkRgnBuilder::Scanline: LastY=%d, fXCount=%d", line->fLastY, line->fXCount);
for (int i = 0; i < line->fXCount; i++) {
SkDebugf(" %d", line->firstX()[i]);
}
SkDebugf("\n");
line = line->nextScanline();
}
}
#endif
private:
/*
* Scanline mimics a row in the region, nearly. A row in a region is:
* [Bottom IntervalCount [L R]... Sentinel]
* while a Scanline is
* [LastY XCount [L R]... uninitialized]
* The two are the same length (which is good), but we have to transmute
* the scanline a little when we convert it to a region-row.
*
* Potentially we could recode this to exactly match the row format, in
* which case copyToRgn() could be a single memcpy. Not sure that is worth
* the effort.
*/
struct Scanline {
SkRegion::RunType fLastY;
SkRegion::RunType fXCount;
SkRegion::RunType* firstX() const { return (SkRegion::RunType*)(this + 1); }
Scanline* nextScanline() const {
// add final +1 for the x-sentinel
return (Scanline*)((SkRegion::RunType*)(this + 1) + fXCount + 1);
}
};
SkRegion::RunType* fStorage;
Scanline* fCurrScanline;
Scanline* fPrevScanline;
// points at next avialable x[] in fCurrScanline
SkRegion::RunType* fCurrXPtr;
SkRegion::RunType fTop; // first Y value
int fStorageCount;
bool collapsWithPrev() {
if (fPrevScanline != nullptr &&
fPrevScanline->fLastY + 1 == fCurrScanline->fLastY &&
fPrevScanline->fXCount == fCurrScanline->fXCount &&
sk_memeq32(fPrevScanline->firstX(), fCurrScanline->firstX(), fCurrScanline->fXCount))
{
// update the height of fPrevScanline
fPrevScanline->fLastY = fCurrScanline->fLastY;
return true;
}
return false;
}
};
SkRgnBuilder::SkRgnBuilder()
: fStorage(nullptr) {
}
SkRgnBuilder::~SkRgnBuilder() {
sk_free(fStorage);
}
bool SkRgnBuilder::init(int maxHeight, int maxTransitions, bool pathIsInverse) {
if ((maxHeight | maxTransitions) < 0) {
return false;
}
if (pathIsInverse) {
// allow for additional X transitions to "invert" each scanline
// [ L' ... normal transitions ... R' ]
//
maxTransitions += 2;
}
// compute the count with +1 and +3 slop for the working buffer
int64_t count = sk_64_mul(maxHeight + 1, 3 + maxTransitions);
if (pathIsInverse) {
// allow for two "empty" rows for the top and bottom
// [ Y, 1, L, R, S] == 5 (*2 for top and bottom)
count += 10;
}
if (count < 0 || !sk_64_isS32(count)) {
return false;
}
fStorageCount = sk_64_asS32(count);
fStorage = (SkRegion::RunType*)sk_malloc_canfail(fStorageCount, sizeof(SkRegion::RunType));
if (nullptr == fStorage) {
return false;
}
fCurrScanline = nullptr; // signal empty collection
fPrevScanline = nullptr; // signal first scanline
return true;
}
void SkRgnBuilder::blitH(int x, int y, int width) {
if (fCurrScanline == nullptr) { // first time
fTop = (SkRegion::RunType)(y);
fCurrScanline = (Scanline*)fStorage;
fCurrScanline->fLastY = (SkRegion::RunType)(y);
fCurrXPtr = fCurrScanline->firstX();
} else {
SkASSERT(y >= fCurrScanline->fLastY);
if (y > fCurrScanline->fLastY) {
// if we get here, we're done with fCurrScanline
fCurrScanline->fXCount = (SkRegion::RunType)((int)(fCurrXPtr - fCurrScanline->firstX()));
int prevLastY = fCurrScanline->fLastY;
if (!this->collapsWithPrev()) {
fPrevScanline = fCurrScanline;
fCurrScanline = fCurrScanline->nextScanline();
}
if (y - 1 > prevLastY) { // insert empty run
fCurrScanline->fLastY = (SkRegion::RunType)(y - 1);
fCurrScanline->fXCount = 0;
fCurrScanline = fCurrScanline->nextScanline();
}
// setup for the new curr line
fCurrScanline->fLastY = (SkRegion::RunType)(y);
fCurrXPtr = fCurrScanline->firstX();
}
}
// check if we should extend the current run, or add a new one
if (fCurrXPtr > fCurrScanline->firstX() && fCurrXPtr[-1] == x) {
fCurrXPtr[-1] = (SkRegion::RunType)(x + width);
} else {
fCurrXPtr[0] = (SkRegion::RunType)(x);
fCurrXPtr[1] = (SkRegion::RunType)(x + width);
fCurrXPtr += 2;
}
SkASSERT(fCurrXPtr - fStorage < fStorageCount);
}
int SkRgnBuilder::computeRunCount() const {
if (fCurrScanline == nullptr) {
return 0;
}
const SkRegion::RunType* line = fStorage;
const SkRegion::RunType* stop = (const SkRegion::RunType*)fCurrScanline;
return 2 + (int)(stop - line);
}
void SkRgnBuilder::copyToRect(SkIRect* r) const {
SkASSERT(fCurrScanline != nullptr);
// A rect's scanline is [bottom intervals left right sentinel] == 5
SkASSERT((const SkRegion::RunType*)fCurrScanline - fStorage == 5);
const Scanline* line = (const Scanline*)fStorage;
SkASSERT(line->fXCount == 2);
r->set(line->firstX()[0], fTop, line->firstX()[1], line->fLastY + 1);
}
void SkRgnBuilder::copyToRgn(SkRegion::RunType runs[]) const {
SkASSERT(fCurrScanline != nullptr);
SkASSERT((const SkRegion::RunType*)fCurrScanline - fStorage > 4);
const Scanline* line = (const Scanline*)fStorage;
const Scanline* stop = fCurrScanline;
*runs++ = fTop;
do {
*runs++ = (SkRegion::RunType)(line->fLastY + 1);
int count = line->fXCount;
*runs++ = count >> 1; // intervalCount
if (count) {
memcpy(runs, line->firstX(), count * sizeof(SkRegion::RunType));
runs += count;
}
*runs++ = SkRegion::kRunTypeSentinel;
line = line->nextScanline();
} while (line < stop);
SkASSERT(line == stop);
*runs = SkRegion::kRunTypeSentinel;
}
static unsigned verb_to_initial_last_index(unsigned verb) {
static const uint8_t gPathVerbToInitialLastIndex[] = {
0, // kMove_Verb
1, // kLine_Verb
2, // kQuad_Verb
2, // kConic_Verb
3, // kCubic_Verb
0, // kClose_Verb
0 // kDone_Verb
};
SkASSERT((unsigned)verb < SK_ARRAY_COUNT(gPathVerbToInitialLastIndex));
return gPathVerbToInitialLastIndex[verb];
}
static unsigned verb_to_max_edges(unsigned verb) {
static const uint8_t gPathVerbToMaxEdges[] = {
0, // kMove_Verb
1, // kLine_Verb
2, // kQuad_VerbB
2, // kConic_VerbB
3, // kCubic_Verb
0, // kClose_Verb
0 // kDone_Verb
};
SkASSERT((unsigned)verb < SK_ARRAY_COUNT(gPathVerbToMaxEdges));
return gPathVerbToMaxEdges[verb];
}
// If returns 0, ignore itop and ibot
static int count_path_runtype_values(const SkPath& path, int* itop, int* ibot) {
SkPath::Iter iter(path, true);
SkPoint pts[4];
SkPath::Verb verb;
int maxEdges = 0;
SkScalar top = SkIntToScalar(SK_MaxS16);
SkScalar bot = SkIntToScalar(SK_MinS16);
while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
maxEdges += verb_to_max_edges(verb);
int lastIndex = verb_to_initial_last_index(verb);
if (lastIndex > 0) {
for (int i = 1; i <= lastIndex; i++) {
if (top > pts[i].fY) {
top = pts[i].fY;
} else if (bot < pts[i].fY) {
bot = pts[i].fY;
}
}
} else if (SkPath::kMove_Verb == verb) {
if (top > pts[0].fY) {
top = pts[0].fY;
} else if (bot < pts[0].fY) {
bot = pts[0].fY;
}
}
}
if (0 == maxEdges) {
return 0; // we have only moves+closes
}
SkASSERT(top <= bot);
*itop = SkScalarRoundToInt(top);
*ibot = SkScalarRoundToInt(bot);
return maxEdges;
}
static bool check_inverse_on_empty_return(SkRegion* dst, const SkPath& path, const SkRegion& clip) {
if (path.isInverseFillType()) {
return dst->set(clip);
} else {
return dst->setEmpty();
}
}
bool SkRegion::setPath(const SkPath& path, const SkRegion& clip) {
SkDEBUGCODE(this->validate();)
if (clip.isEmpty() || !path.isFinite()) {
return this->setEmpty();
}
if (path.isEmpty()) {
return check_inverse_on_empty_return(this, path, clip);
}
// compute worst-case rgn-size for the path
int pathTop, pathBot;
int pathTransitions = count_path_runtype_values(path, &pathTop, &pathBot);
if (0 == pathTransitions) {
return check_inverse_on_empty_return(this, path, clip);
}
int clipTop, clipBot;
int clipTransitions = clip.count_runtype_values(&clipTop, &clipBot);
int top = SkMax32(pathTop, clipTop);
int bot = SkMin32(pathBot, clipBot);
if (top >= bot) {
return check_inverse_on_empty_return(this, path, clip);
}
SkRgnBuilder builder;
if (!builder.init(bot - top,
SkMax32(pathTransitions, clipTransitions),
path.isInverseFillType())) {
// can't allocate working space, so return false
return this->setEmpty();
}
SkScan::FillPath(path, clip, &builder);
builder.done();
int count = builder.computeRunCount();
if (count == 0) {
return this->setEmpty();
} else if (count == kRectRegionRuns) {
builder.copyToRect(&fBounds);
this->setRect(fBounds);
} else {
SkRegion tmp;
tmp.fRunHead = RunHead::Alloc(count);
builder.copyToRgn(tmp.fRunHead->writable_runs());
tmp.fRunHead->computeRunBounds(&tmp.fBounds);
this->swap(tmp);
}
SkDEBUGCODE(this->validate();)
return true;
}
/////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////
struct Edge {
enum {
kY0Link = 0x01,
kY1Link = 0x02,
kCompleteLink = (kY0Link | kY1Link)
};
SkRegion::RunType fX;
SkRegion::RunType fY0, fY1;
uint8_t fFlags;
Edge* fNext;
void set(int x, int y0, int y1) {
SkASSERT(y0 != y1);
fX = (SkRegion::RunType)(x);
fY0 = (SkRegion::RunType)(y0);
fY1 = (SkRegion::RunType)(y1);
fFlags = 0;
SkDEBUGCODE(fNext = nullptr;)
}
int top() const {
return SkFastMin32(fY0, fY1);
}
};
static void find_link(Edge* base, Edge* stop) {
SkASSERT(base < stop);
if (base->fFlags == Edge::kCompleteLink) {
SkASSERT(base->fNext);
return;
}
SkASSERT(base + 1 < stop);
int y0 = base->fY0;
int y1 = base->fY1;
Edge* e = base;
if ((base->fFlags & Edge::kY0Link) == 0) {
for (;;) {
e += 1;
if ((e->fFlags & Edge::kY1Link) == 0 && y0 == e->fY1) {
SkASSERT(nullptr == e->fNext);
e->fNext = base;
e->fFlags = SkToU8(e->fFlags | Edge::kY1Link);
break;
}
}
}
e = base;
if ((base->fFlags & Edge::kY1Link) == 0) {
for (;;) {
e += 1;
if ((e->fFlags & Edge::kY0Link) == 0 && y1 == e->fY0) {
SkASSERT(nullptr == base->fNext);
base->fNext = e;
e->fFlags = SkToU8(e->fFlags | Edge::kY0Link);
break;
}
}
}
base->fFlags = Edge::kCompleteLink;
}
static int extract_path(Edge* edge, Edge* stop, SkPath* path) {
while (0 == edge->fFlags) {
edge++; // skip over "used" edges
}
SkASSERT(edge < stop);
Edge* base = edge;
Edge* prev = edge;
edge = edge->fNext;
SkASSERT(edge != base);
int count = 1;
path->moveTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY0));
prev->fFlags = 0;
do {
if (prev->fX != edge->fX || prev->fY1 != edge->fY0) { // skip collinear
path->lineTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY1)); // V
path->lineTo(SkIntToScalar(edge->fX), SkIntToScalar(edge->fY0)); // H
}
prev = edge;
edge = edge->fNext;
count += 1;
prev->fFlags = 0;
} while (edge != base);
path->lineTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY1)); // V
path->close();
return count;
}
struct EdgeLT {
bool operator()(const Edge& a, const Edge& b) const {
return (a.fX == b.fX) ? a.top() < b.top() : a.fX < b.fX;
}
};
bool SkRegion::getBoundaryPath(SkPath* path) const {
// path could safely be nullptr if we're empty, but the caller shouldn't
// *know* that
SkASSERT(path);
if (this->isEmpty()) {
return false;
}
const SkIRect& bounds = this->getBounds();
if (this->isRect()) {
SkRect r;
r.set(bounds); // this converts the ints to scalars
path->addRect(r);
return true;
}
SkRegion::Iterator iter(*this);
SkTDArray<Edge> edges;
for (const SkIRect& r = iter.rect(); !iter.done(); iter.next()) {
Edge* edge = edges.append(2);
edge[0].set(r.fLeft, r.fBottom, r.fTop);
edge[1].set(r.fRight, r.fTop, r.fBottom);
}
int count = edges.count();
Edge* start = edges.begin();
Edge* stop = start + count;
SkTQSort<Edge>(start, stop - 1, EdgeLT());
Edge* e;
for (e = start; e != stop; e++) {
find_link(e, stop);
}
#ifdef SK_DEBUG
for (e = start; e != stop; e++) {
SkASSERT(e->fNext != nullptr);
SkASSERT(e->fFlags == Edge::kCompleteLink);
}
#endif
path->incReserve(count << 1);
do {
SkASSERT(count > 1);
count -= extract_path(start, stop, path);
} while (count > 0);
return true;
}