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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.
*/
#ifndef SkRegionPriv_DEFINED
#define SkRegionPriv_DEFINED
#include "include/core/SkRegion.h"
#include "include/private/base/SkMalloc.h"
#include "include/private/base/SkMath.h"
#include "include/private/base/SkTo.h"
#include <atomic>
#include <functional>
class SkRegionPriv {
public:
inline static constexpr int kRunTypeSentinel = 0x7FFFFFFF;
typedef SkRegion::RunType RunType;
typedef SkRegion::RunHead RunHead;
// Call the function with each span, in Y -> X ascending order.
// We pass a rect, but we will still ensure the span Y->X ordering, so often the height
// of the rect may be 1. It should never be empty.
static void VisitSpans(const SkRegion& rgn, const std::function<void(const SkIRect&)>&);
#ifdef SK_DEBUG
static void Validate(const SkRegion& rgn);
#endif
};
static constexpr int SkRegion_kRunTypeSentinel = 0x7FFFFFFF;
inline bool SkRegionValueIsSentinel(int32_t value) {
return value == (int32_t)SkRegion_kRunTypeSentinel;
}
#define assert_sentinel(value, isSentinel) \
SkASSERT(SkRegionValueIsSentinel(value) == isSentinel)
#ifdef SK_DEBUG
// Given the first interval (just past the interval-count), compute the
// interval count, by search for the x-sentinel
//
static int compute_intervalcount(const SkRegionPriv::RunType runs[]) {
const SkRegionPriv::RunType* curr = runs;
while (*curr < SkRegion_kRunTypeSentinel) {
SkASSERT(curr[0] < curr[1]);
SkASSERT(curr[1] < SkRegion_kRunTypeSentinel);
curr += 2;
}
return SkToInt((curr - runs) >> 1);
}
#endif
struct SkRegion::RunHead {
private:
public:
std::atomic<int32_t> fRefCnt;
int32_t fRunCount;
/**
* Number of spans with different Y values. This does not count the initial
* Top value, nor does it count the final Y-Sentinel value. In the logical
* case of a rectangle, this would return 1, and an empty region would
* return 0.
*/
int getYSpanCount() const {
return fYSpanCount;
}
/**
* Number of intervals in the entire region. This equals the number of
* rects that would be returned by the Iterator. In the logical case of
* a rect, this would return 1, and an empty region would return 0.
*/
int getIntervalCount() const {
return fIntervalCount;
}
static RunHead* Alloc(int count) {
if (count < SkRegion::kRectRegionRuns) {
return nullptr;
}
const int64_t size = sk_64_mul(count, sizeof(RunType)) + sizeof(RunHead);
if (count < 0 || !SkTFitsIn<int32_t>(size)) { SK_ABORT("Invalid Size"); }
RunHead* head = (RunHead*)sk_malloc_throw(size);
head->fRefCnt = 1;
head->fRunCount = count;
// these must be filled in later, otherwise we will be invalid
head->fYSpanCount = 0;
head->fIntervalCount = 0;
return head;
}
static RunHead* Alloc(int count, int yspancount, int intervalCount) {
if (yspancount <= 0 || intervalCount <= 1) {
return nullptr;
}
RunHead* head = Alloc(count);
if (!head) {
return nullptr;
}
head->fYSpanCount = yspancount;
head->fIntervalCount = intervalCount;
return head;
}
SkRegion::RunType* writable_runs() {
SkASSERT(fRefCnt == 1);
return (SkRegion::RunType*)(this + 1);
}
const SkRegion::RunType* readonly_runs() const {
return (const SkRegion::RunType*)(this + 1);
}
RunHead* ensureWritable() {
RunHead* writable = this;
if (fRefCnt > 1) {
// We need to alloc & copy the current region before decrease
// the refcount because it could be freed in the meantime.
writable = Alloc(fRunCount, fYSpanCount, fIntervalCount);
memcpy(writable->writable_runs(), this->readonly_runs(),
fRunCount * sizeof(RunType));
// fRefCount might have changed since we last checked.
// If we own the last reference at this point, we need to
// free the memory.
if (--fRefCnt == 0) {
sk_free(this);
}
}
return writable;
}
/**
* Given a scanline (including its Bottom value at runs[0]), return the next
* scanline. Asserts that there is one (i.e. runs[0] < Sentinel)
*/
static SkRegion::RunType* SkipEntireScanline(const SkRegion::RunType runs[]) {
// we are not the Y Sentinel
SkASSERT(runs[0] < SkRegion_kRunTypeSentinel);
const int intervals = runs[1];
SkASSERT(runs[2 + intervals * 2] == SkRegion_kRunTypeSentinel);
#ifdef SK_DEBUG
{
int n = compute_intervalcount(&runs[2]);
SkASSERT(n == intervals);
}
#endif
// skip the entire line [B N [L R] S]
runs += 1 + 1 + intervals * 2 + 1;
return const_cast<SkRegion::RunType*>(runs);
}
/**
* Return the scanline that contains the Y value. This requires that the Y
* value is already known to be contained within the bounds of the region,
* and so this routine never returns nullptr.
*
* It returns the beginning of the scanline, starting with its Bottom value.
*/
SkRegion::RunType* findScanline(int y) const {
const RunType* runs = this->readonly_runs();
// if the top-check fails, we didn't do a quick check on the bounds
SkASSERT(y >= runs[0]);
runs += 1; // skip top-Y
for (;;) {
int bottom = runs[0];
// If we hit this, we've walked off the region, and our bounds check
// failed.
SkASSERT(bottom < SkRegion_kRunTypeSentinel);
if (y < bottom) {
break;
}
runs = SkipEntireScanline(runs);
}
return const_cast<SkRegion::RunType*>(runs);
}
// Copy src runs into us, computing interval counts and bounds along the way
void computeRunBounds(SkIRect* bounds) {
RunType* runs = this->writable_runs();
bounds->fTop = *runs++;
int bot;
int ySpanCount = 0;
int intervalCount = 0;
int left = SK_MaxS32;
int rite = SK_MinS32;
do {
bot = *runs++;
SkASSERT(bot < SkRegion_kRunTypeSentinel);
ySpanCount += 1;
const int intervals = *runs++;
SkASSERT(intervals >= 0);
SkASSERT(intervals < SkRegion_kRunTypeSentinel);
if (intervals > 0) {
#ifdef SK_DEBUG
{
int n = compute_intervalcount(runs);
SkASSERT(n == intervals);
}
#endif
RunType L = runs[0];
SkASSERT(L < SkRegion_kRunTypeSentinel);
if (left > L) {
left = L;
}
runs += intervals * 2;
RunType R = runs[-1];
SkASSERT(R < SkRegion_kRunTypeSentinel);
if (rite < R) {
rite = R;
}
intervalCount += intervals;
}
SkASSERT(SkRegion_kRunTypeSentinel == *runs);
runs += 1; // skip x-sentinel
// test Y-sentinel
} while (SkRegion_kRunTypeSentinel > *runs);
#ifdef SK_DEBUG
// +1 to skip the last Y-sentinel
int runCount = SkToInt(runs - this->writable_runs() + 1);
SkASSERT(runCount == fRunCount);
#endif
fYSpanCount = ySpanCount;
fIntervalCount = intervalCount;
bounds->fLeft = left;
bounds->fRight = rite;
bounds->fBottom = bot;
}
private:
int32_t fYSpanCount;
int32_t fIntervalCount;
};
#endif