/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkEdgeBuilder.h"
#include "SkPath.h"
#include "SkEdge.h"
#include "SkEdgeClipper.h"
#include "SkLineClipper.h"
#include "SkGeometry.h"
template <typename T> static T* typedAllocThrow(SkChunkAlloc& alloc) {
return static_cast<T*>(alloc.allocThrow(sizeof(T)));
}
///////////////////////////////////////////////////////////////////////////////
SkEdgeBuilder::SkEdgeBuilder() : fAlloc(16*1024) {
fEdgeList = nullptr;
}
SkEdgeBuilder::Combine SkEdgeBuilder::CombineVertical(const SkEdge* edge, SkEdge* last) {
if (last->fCurveCount || last->fDX || edge->fX != last->fX) {
return kNo_Combine;
}
if (edge->fWinding == last->fWinding) {
if (edge->fLastY + 1 == last->fFirstY) {
last->fFirstY = edge->fFirstY;
return kPartial_Combine;
}
if (edge->fFirstY == last->fLastY + 1) {
last->fLastY = edge->fLastY;
return kPartial_Combine;
}
return kNo_Combine;
}
if (edge->fFirstY == last->fFirstY) {
if (edge->fLastY == last->fLastY) {
return kTotal_Combine;
}
if (edge->fLastY < last->fLastY) {
last->fFirstY = edge->fLastY + 1;
return kPartial_Combine;
}
last->fFirstY = last->fLastY + 1;
last->fLastY = edge->fLastY;
last->fWinding = edge->fWinding;
return kPartial_Combine;
}
if (edge->fLastY == last->fLastY) {
if (edge->fFirstY > last->fFirstY) {
last->fLastY = edge->fFirstY - 1;
return kPartial_Combine;
}
last->fLastY = last->fFirstY - 1;
last->fFirstY = edge->fFirstY;
last->fWinding = edge->fWinding;
return kPartial_Combine;
}
return kNo_Combine;
}
static bool vertical_line(const SkEdge* edge) {
return !edge->fDX && !edge->fCurveCount;
}
void SkEdgeBuilder::addLine(const SkPoint pts[]) {
SkEdge* edge = typedAllocThrow<SkEdge>(fAlloc);
if (edge->setLine(pts[0], pts[1], fShiftUp)) {
if (vertical_line(edge) && fList.count()) {
Combine combine = CombineVertical(edge, *(fList.end() - 1));
if (kNo_Combine != combine) {
if (kTotal_Combine == combine) {
fList.pop();
}
goto unallocate_edge;
}
}
fList.push(edge);
} else {
unallocate_edge:
;
// TODO: unallocate edge from storage...
}
}
void SkEdgeBuilder::addQuad(const SkPoint pts[]) {
SkQuadraticEdge* edge = typedAllocThrow<SkQuadraticEdge>(fAlloc);
if (edge->setQuadratic(pts, fShiftUp)) {
fList.push(edge);
} else {
// TODO: unallocate edge from storage...
}
}
void SkEdgeBuilder::addCubic(const SkPoint pts[]) {
SkCubicEdge* edge = typedAllocThrow<SkCubicEdge>(fAlloc);
if (edge->setCubic(pts, fShiftUp)) {
fList.push(edge);
} else {
// TODO: unallocate edge from storage...
}
}
void SkEdgeBuilder::addClipper(SkEdgeClipper* clipper) {
SkPoint pts[4];
SkPath::Verb verb;
while ((verb = clipper->next(pts)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kLine_Verb:
this->addLine(pts);
break;
case SkPath::kQuad_Verb:
this->addQuad(pts);
break;
case SkPath::kCubic_Verb:
this->addCubic(pts);
break;
default:
break;
}
}
}
///////////////////////////////////////////////////////////////////////////////
static void setShiftedClip(SkRect* dst, const SkIRect& src, int shift) {
dst->set(SkIntToScalar(src.fLeft >> shift),
SkIntToScalar(src.fTop >> shift),
SkIntToScalar(src.fRight >> shift),
SkIntToScalar(src.fBottom >> shift));
}
SkEdgeBuilder::Combine SkEdgeBuilder::checkVertical(const SkEdge* edge, SkEdge** edgePtr) {
return !vertical_line(edge) || edgePtr <= fEdgeList ? kNo_Combine :
CombineVertical(edge, edgePtr[-1]);
}
int SkEdgeBuilder::buildPoly(const SkPath& path, const SkIRect* iclip, int shiftUp,
bool canCullToTheRight) {
SkPath::Iter iter(path, true);
SkPoint pts[4];
SkPath::Verb verb;
int maxEdgeCount = path.countPoints();
if (iclip) {
// clipping can turn 1 line into (up to) kMaxClippedLineSegments, since
// we turn portions that are clipped out on the left/right into vertical
// segments.
maxEdgeCount *= SkLineClipper::kMaxClippedLineSegments;
}
size_t maxEdgeSize = maxEdgeCount * sizeof(SkEdge);
size_t maxEdgePtrSize = maxEdgeCount * sizeof(SkEdge*);
// lets store the edges and their pointers in the same block
char* storage = (char*)fAlloc.allocThrow(maxEdgeSize + maxEdgePtrSize);
SkEdge* edge = reinterpret_cast<SkEdge*>(storage);
SkEdge** edgePtr = reinterpret_cast<SkEdge**>(storage + maxEdgeSize);
// Record the beginning of our pointers, so we can return them to the caller
fEdgeList = edgePtr;
if (iclip) {
SkRect clip;
setShiftedClip(&clip, *iclip, shiftUp);
while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kMove_Verb:
case SkPath::kClose_Verb:
// we ignore these, and just get the whole segment from
// the corresponding line/quad/cubic verbs
break;
case SkPath::kLine_Verb: {
SkPoint lines[SkLineClipper::kMaxPoints];
int lineCount = SkLineClipper::ClipLine(pts, clip, lines, canCullToTheRight);
SkASSERT(lineCount <= SkLineClipper::kMaxClippedLineSegments);
for (int i = 0; i < lineCount; i++) {
if (edge->setLine(lines[i], lines[i + 1], shiftUp)) {
Combine combine = checkVertical(edge, edgePtr);
if (kNo_Combine == combine) {
*edgePtr++ = edge++;
} else if (kTotal_Combine == combine) {
--edgePtr;
}
}
}
break;
}
default:
SkDEBUGFAIL("unexpected verb");
break;
}
}
} else {
while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kMove_Verb:
case SkPath::kClose_Verb:
// we ignore these, and just get the whole segment from
// the corresponding line/quad/cubic verbs
break;
case SkPath::kLine_Verb:
if (edge->setLine(pts[0], pts[1], shiftUp)) {
Combine combine = checkVertical(edge, edgePtr);
if (kNo_Combine == combine) {
*edgePtr++ = edge++;
} else if (kTotal_Combine == combine) {
--edgePtr;
}
}
break;
default:
SkDEBUGFAIL("unexpected verb");
break;
}
}
}
SkASSERT((char*)edge <= (char*)fEdgeList);
SkASSERT(edgePtr - fEdgeList <= maxEdgeCount);
return SkToInt(edgePtr - fEdgeList);
}
static void handle_quad(SkEdgeBuilder* builder, const SkPoint pts[3]) {
SkPoint monoX[5];
int n = SkChopQuadAtYExtrema(pts, monoX);
for (int i = 0; i <= n; i++) {
builder->addQuad(&monoX[i * 2]);
}
}
int SkEdgeBuilder::build(const SkPath& path, const SkIRect* iclip, int shiftUp,
bool canCullToTheRight) {
fAlloc.reset();
fList.reset();
fShiftUp = shiftUp;
if (SkPath::kLine_SegmentMask == path.getSegmentMasks()) {
return this->buildPoly(path, iclip, shiftUp, canCullToTheRight);
}
SkAutoConicToQuads quadder;
const SkScalar conicTol = SK_Scalar1 / 4;
SkPath::Iter iter(path, true);
SkPoint pts[4];
SkPath::Verb verb;
if (iclip) {
SkRect clip;
setShiftedClip(&clip, *iclip, shiftUp);
SkEdgeClipper clipper(canCullToTheRight);
while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kMove_Verb:
case SkPath::kClose_Verb:
// we ignore these, and just get the whole segment from
// the corresponding line/quad/cubic verbs
break;
case SkPath::kLine_Verb: {
SkPoint lines[SkLineClipper::kMaxPoints];
int lineCount = SkLineClipper::ClipLine(pts, clip, lines, canCullToTheRight);
for (int i = 0; i < lineCount; i++) {
this->addLine(&lines[i]);
}
break;
}
case SkPath::kQuad_Verb:
if (clipper.clipQuad(pts, clip)) {
this->addClipper(&clipper);
}
break;
case SkPath::kConic_Verb: {
const SkPoint* quadPts = quadder.computeQuads(
pts, iter.conicWeight(), conicTol);
for (int i = 0; i < quadder.countQuads(); ++i) {
if (clipper.clipQuad(quadPts, clip)) {
this->addClipper(&clipper);
}
quadPts += 2;
}
} break;
case SkPath::kCubic_Verb:
if (clipper.clipCubic(pts, clip)) {
this->addClipper(&clipper);
}
break;
default:
SkDEBUGFAIL("unexpected verb");
break;
}
}
} else {
while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kMove_Verb:
case SkPath::kClose_Verb:
// we ignore these, and just get the whole segment from
// the corresponding line/quad/cubic verbs
break;
case SkPath::kLine_Verb:
this->addLine(pts);
break;
case SkPath::kQuad_Verb: {
handle_quad(this, pts);
break;
}
case SkPath::kConic_Verb: {
const SkPoint* quadPts = quadder.computeQuads(
pts, iter.conicWeight(), conicTol);
for (int i = 0; i < quadder.countQuads(); ++i) {
handle_quad(this, quadPts);
quadPts += 2;
}
} break;
case SkPath::kCubic_Verb: {
SkPoint monoY[10];
int n = SkChopCubicAtYExtrema(pts, monoY);
for (int i = 0; i <= n; i++) {
this->addCubic(&monoY[i * 3]);
}
break;
}
default:
SkDEBUGFAIL("unexpected verb");
break;
}
}
}
fEdgeList = fList.begin();
return fList.count();
}