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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 SkScanPriv_DEFINED
#define SkScanPriv_DEFINED
#include "SkPath.h"
#include "SkScan.h"
#include "SkBlitter.h"
class SkScanClipper {
SkScanClipper(SkBlitter* blitter, const SkRegion* clip, const SkIRect& bounds,
bool skipRejectTest = false);
SkBlitter* getBlitter() const { return fBlitter; }
const SkIRect* getClipRect() const { return fClipRect; }
SkRectClipBlitter fRectBlitter;
SkRgnClipBlitter fRgnBlitter;
#ifdef SK_DEBUG
SkRectClipCheckBlitter fRectClipCheckBlitter;
SkBlitter* fBlitter;
const SkIRect* fClipRect;
void sk_fill_path(const SkPath& path, const SkIRect& clipRect,
SkBlitter* blitter, int start_y, int stop_y, int shiftEdgesUp,
bool pathContainedInClip);
// blit the rects above and below avoid, clipped to clip
void sk_blit_above(SkBlitter*, const SkIRect& avoid, const SkRegion& clip);
void sk_blit_below(SkBlitter*, const SkIRect& avoid, const SkRegion& clip);
template<class EdgeType>
static inline void remove_edge(EdgeType* edge) {
edge->fPrev->fNext = edge->fNext;
edge->fNext->fPrev = edge->fPrev;
template<class EdgeType>
static inline void insert_edge_after(EdgeType* edge, EdgeType* afterMe) {
edge->fPrev = afterMe;
edge->fNext = afterMe->fNext;
afterMe->fNext->fPrev = edge;
afterMe->fNext = edge;
template<class EdgeType>
static void backward_insert_edge_based_on_x(EdgeType* edge) {
SkFixed x = edge->fX;
EdgeType* prev = edge->fPrev;
while (prev->fPrev && prev->fX > x) {
prev = prev->fPrev;
if (prev->fNext != edge) {
insert_edge_after(edge, prev);
// Start from the right side, searching backwards for the point to begin the new edge list
// insertion, marching forwards from here. The implementation could have started from the left
// of the prior insertion, and search to the right, or with some additional caching, binary
// search the starting point. More work could be done to determine optimal new edge insertion.
template<class EdgeType>
static EdgeType* backward_insert_start(EdgeType* prev, SkFixed x) {
while (prev->fPrev && prev->fX > x) {
prev = prev->fPrev;
return prev;
static bool fitsInsideLimit(const SkRect& r, SkScalar max) {
const SkScalar min = -max;
return r.fLeft > min && r.fTop > min &&
r.fRight < max && r.fBottom < max;
static int overflows_short_shift(int value, int shift) {
const int s = 16 + shift;
return (SkLeftShift(value, s) >> s) - value;
Would any of the coordinates of this rectangle not fit in a short,
when left-shifted by shift?
static int rect_overflows_short_shift(SkIRect rect, int shift) {
SkASSERT(!overflows_short_shift(8191, shift));
SkASSERT(overflows_short_shift(8192, shift));
SkASSERT(!overflows_short_shift(32767, 0));
SkASSERT(overflows_short_shift(32768, 0));
// Since we expect these to succeed, we bit-or together
// for a tiny extra bit of speed.
return overflows_short_shift(rect.fLeft, shift) |
overflows_short_shift(rect.fRight, shift) |
overflows_short_shift(rect.fTop, shift) |
overflows_short_shift(rect.fBottom, shift);
static bool safeRoundOut(const SkRect& src, SkIRect* dst, int32_t maxInt) {
const SkScalar maxScalar = SkIntToScalar(maxInt);
if (fitsInsideLimit(src, maxScalar)) {
return true;
return false;
using FillPathFunc = std::function<void(const SkPath& path, SkBlitter* blitter, bool isInverse,
const SkIRect& ir, const SkRegion* clipRgn, const SkIRect* clipRect, bool forceRLE)>;
static inline void do_fill_path(const SkPath& path, const SkRegion& origClip, SkBlitter* blitter,
bool forceRLE, const int SHIFT, FillPathFunc fillPathFunc) {
if (origClip.isEmpty()) {
const bool isInverse = path.isInverseFillType();
SkIRect ir;
if (!safeRoundOut(path.getBounds(), &ir, SK_MaxS32 >> SHIFT)) {
// Bounds can't fit in SkIRect; we'll return without drawing
if (ir.isEmpty()) {
if (isInverse) {
// If the intersection of the path bounds and the clip bounds
// will overflow 32767 when << by SHIFT, we can't supersample,
// so draw without antialiasing.
SkIRect clippedIR;
if (isInverse) {
// If the path is an inverse fill, it's going to fill the entire
// clip, and we care whether the entire clip exceeds our limits.
clippedIR = origClip.getBounds();
} else {
if (!clippedIR.intersect(ir, origClip.getBounds())) {
if (rect_overflows_short_shift(clippedIR, SHIFT)) {
SkScan::FillPath(path, origClip, blitter);
// Our antialiasing can't handle a clip larger than 32767, so we restrict
// the clip to that limit here. (the runs[] uses int16_t for its index).
// A more general solution (one that could also eliminate the need to
// disable aa based on ir bounds (see overflows_short_shift) would be
// to tile the clip/target...
SkRegion tmpClipStorage;
const SkRegion* clipRgn = &origClip;
static const int32_t kMaxClipCoord = 32767;
const SkIRect& bounds = origClip.getBounds();
if (bounds.fRight > kMaxClipCoord || bounds.fBottom > kMaxClipCoord) {
SkIRect limit = { 0, 0, kMaxClipCoord, kMaxClipCoord };
tmpClipStorage.op(origClip, limit, SkRegion::kIntersect_Op);
clipRgn = &tmpClipStorage;
// for here down, use clipRgn, not origClip
SkScanClipper clipper(blitter, clipRgn, ir);
const SkIRect* clipRect = clipper.getClipRect();
if (clipper.getBlitter() == nullptr) { // clipped out
if (isInverse) {
SkASSERT(clipper.getClipRect() == nullptr ||
*clipper.getClipRect() == clipRgn->getBounds());
// now use the (possibly wrapped) blitter
blitter = clipper.getBlitter();
if (isInverse) {
sk_blit_above(blitter, ir, *clipRgn);
SkASSERT(SkIntToScalar(ir.fTop) <= path.getBounds().fTop);
fillPathFunc(path, blitter, isInverse, ir, clipRgn, clipRect, forceRLE);
if (isInverse) {
sk_blit_below(blitter, ir, *clipRgn);