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skia2/tests/PathOpsTestCommon.cpp
John Stiles 886a904595 Update SkTQSort to use half-open ranges. 
C++ algorithms have largely standardized on a [begin, end) half-open
range, as seen in standard library containers. SkTQSort now adheres to
this model, and takes vec.begin() and vec.end() as its inputs.

To avoid confusion between inclusive and half-open ranges inside the
implementation, internal helper functions now take "left" and "count"
arguments instead of "left"/"right" or "begin"/"end". This avoids any
ambiguity.

(Although performance was not the main goal, this CL appears to
slightly improve our sorting benchmark on my machine.)

Change-Id: I5e96b6730be96cf23d001ee0915c69764b2c024a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/302579
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
2020-07-14 22:13:59 +00:00

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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/core/SkPathPriv.h"
#include "src/core/SkTSort.h"
#include "src/pathops/SkPathOpsBounds.h"
#include "src/pathops/SkPathOpsConic.h"
#include "src/pathops/SkPathOpsCubic.h"
#include "src/pathops/SkPathOpsLine.h"
#include "src/pathops/SkPathOpsQuad.h"
#include "src/pathops/SkPathOpsTSect.h"
#include "src/pathops/SkReduceOrder.h"
#include "tests/PathOpsTestCommon.h"
#include <utility>
static double calc_t_div(const SkDCubic& cubic, double precision, double start) {
const double adjust = sqrt(3.) / 36;
SkDCubic sub;
const SkDCubic* cPtr;
if (start == 0) {
cPtr = &cubic;
} else {
// OPTIMIZE: special-case half-split ?
sub = cubic.subDivide(start, 1);
cPtr = &sub;
}
const SkDCubic& c = *cPtr;
double dx = c[3].fX - 3 * (c[2].fX - c[1].fX) - c[0].fX;
double dy = c[3].fY - 3 * (c[2].fY - c[1].fY) - c[0].fY;
double dist = sqrt(dx * dx + dy * dy);
double tDiv3 = precision / (adjust * dist);
double t = SkDCubeRoot(tDiv3);
if (start > 0) {
t = start + (1 - start) * t;
}
return t;
}
static bool add_simple_ts(const SkDCubic& cubic, double precision, SkTArray<double, true>* ts) {
double tDiv = calc_t_div(cubic, precision, 0);
if (tDiv >= 1) {
return true;
}
if (tDiv >= 0.5) {
ts->push_back(0.5);
return true;
}
return false;
}
static void addTs(const SkDCubic& cubic, double precision, double start, double end,
SkTArray<double, true>* ts) {
double tDiv = calc_t_div(cubic, precision, 0);
double parts = ceil(1.0 / tDiv);
for (double index = 0; index < parts; ++index) {
double newT = start + (index / parts) * (end - start);
if (newT > 0 && newT < 1) {
ts->push_back(newT);
}
}
}
static void toQuadraticTs(const SkDCubic* cubic, double precision, SkTArray<double, true>* ts) {
SkReduceOrder reducer;
int order = reducer.reduce(*cubic, SkReduceOrder::kAllow_Quadratics);
if (order < 3) {
return;
}
double inflectT[5];
int inflections = cubic->findInflections(inflectT);
SkASSERT(inflections <= 2);
if (!cubic->endsAreExtremaInXOrY()) {
inflections += cubic->findMaxCurvature(&inflectT[inflections]);
SkASSERT(inflections <= 5);
}
SkTQSort<double>(inflectT, inflectT + inflections);
// OPTIMIZATION: is this filtering common enough that it needs to be pulled out into its
// own subroutine?
while (inflections && approximately_less_than_zero(inflectT[0])) {
memmove(inflectT, &inflectT[1], sizeof(inflectT[0]) * --inflections);
}
int start = 0;
int next = 1;
while (next < inflections) {
if (!approximately_equal(inflectT[start], inflectT[next])) {
++start;
++next;
continue;
}
memmove(&inflectT[start], &inflectT[next], sizeof(inflectT[0]) * (--inflections - start));
}
while (inflections && approximately_greater_than_one(inflectT[inflections - 1])) {
--inflections;
}
SkDCubicPair pair;
if (inflections == 1) {
pair = cubic->chopAt(inflectT[0]);
int orderP1 = reducer.reduce(pair.first(), SkReduceOrder::kNo_Quadratics);
if (orderP1 < 2) {
--inflections;
} else {
int orderP2 = reducer.reduce(pair.second(), SkReduceOrder::kNo_Quadratics);
if (orderP2 < 2) {
--inflections;
}
}
}
if (inflections == 0 && add_simple_ts(*cubic, precision, ts)) {
return;
}
if (inflections == 1) {
pair = cubic->chopAt(inflectT[0]);
addTs(pair.first(), precision, 0, inflectT[0], ts);
addTs(pair.second(), precision, inflectT[0], 1, ts);
return;
}
if (inflections > 1) {
SkDCubic part = cubic->subDivide(0, inflectT[0]);
addTs(part, precision, 0, inflectT[0], ts);
int last = inflections - 1;
for (int idx = 0; idx < last; ++idx) {
part = cubic->subDivide(inflectT[idx], inflectT[idx + 1]);
addTs(part, precision, inflectT[idx], inflectT[idx + 1], ts);
}
part = cubic->subDivide(inflectT[last], 1);
addTs(part, precision, inflectT[last], 1, ts);
return;
}
addTs(*cubic, precision, 0, 1, ts);
}
void CubicToQuads(const SkDCubic& cubic, double precision, SkTArray<SkDQuad, true>& quads) {
SkTArray<double, true> ts;
toQuadraticTs(&cubic, precision, &ts);
if (ts.count() <= 0) {
SkDQuad quad = cubic.toQuad();
quads.push_back(quad);
return;
}
double tStart = 0;
for (int i1 = 0; i1 <= ts.count(); ++i1) {
const double tEnd = i1 < ts.count() ? ts[i1] : 1;
SkDRect bounds;
bounds.setBounds(cubic);
SkDCubic part = cubic.subDivide(tStart, tEnd);
SkDQuad quad = part.toQuad();
if (quad[1].fX < bounds.fLeft) {
quad[1].fX = bounds.fLeft;
} else if (quad[1].fX > bounds.fRight) {
quad[1].fX = bounds.fRight;
}
if (quad[1].fY < bounds.fTop) {
quad[1].fY = bounds.fTop;
} else if (quad[1].fY > bounds.fBottom) {
quad[1].fY = bounds.fBottom;
}
quads.push_back(quad);
tStart = tEnd;
}
}
void CubicPathToQuads(const SkPath& cubicPath, SkPath* quadPath) {
quadPath->reset();
SkDCubic cubic;
SkTArray<SkDQuad, true> quads;
for (auto [verb, pts, w] : SkPathPriv::Iterate(cubicPath)) {
switch (verb) {
case SkPathVerb::kMove:
quadPath->moveTo(pts[0].fX, pts[0].fY);
continue;
case SkPathVerb::kLine:
quadPath->lineTo(pts[1].fX, pts[1].fY);
break;
case SkPathVerb::kQuad:
quadPath->quadTo(pts[1].fX, pts[1].fY, pts[2].fX, pts[2].fY);
break;
case SkPathVerb::kCubic:
quads.reset();
cubic.set(pts);
CubicToQuads(cubic, cubic.calcPrecision(), quads);
for (int index = 0; index < quads.count(); ++index) {
SkPoint qPts[2] = {
quads[index][1].asSkPoint(),
quads[index][2].asSkPoint()
};
quadPath->quadTo(qPts[0].fX, qPts[0].fY, qPts[1].fX, qPts[1].fY);
}
break;
case SkPathVerb::kClose:
quadPath->close();
break;
default:
SkDEBUGFAIL("bad verb");
return;
}
}
}
void CubicPathToSimple(const SkPath& cubicPath, SkPath* simplePath) {
simplePath->reset();
SkDCubic cubic;
for (auto [verb, pts, w] : SkPathPriv::Iterate(cubicPath)) {
switch (verb) {
case SkPathVerb::kMove:
simplePath->moveTo(pts[0].fX, pts[0].fY);
continue;
case SkPathVerb::kLine:
simplePath->lineTo(pts[1].fX, pts[1].fY);
break;
case SkPathVerb::kQuad:
simplePath->quadTo(pts[1].fX, pts[1].fY, pts[2].fX, pts[2].fY);
break;
case SkPathVerb::kCubic: {
cubic.set(pts);
double tInflects[2];
int inflections = cubic.findInflections(tInflects);
if (inflections > 1 && tInflects[0] > tInflects[1]) {
using std::swap;
swap(tInflects[0], tInflects[1]);
}
double lo = 0;
for (int index = 0; index <= inflections; ++index) {
double hi = index < inflections ? tInflects[index] : 1;
SkDCubic part = cubic.subDivide(lo, hi);
SkPoint cPts[3];
cPts[0] = part[1].asSkPoint();
cPts[1] = part[2].asSkPoint();
cPts[2] = part[3].asSkPoint();
simplePath->cubicTo(cPts[0].fX, cPts[0].fY, cPts[1].fX, cPts[1].fY,
cPts[2].fX, cPts[2].fY);
lo = hi;
}
break;
}
case SkPathVerb::kClose:
simplePath->close();
break;
default:
SkDEBUGFAIL("bad verb");
return;
}
}
}
bool ValidBounds(const SkPathOpsBounds& bounds) {
if (SkScalarIsNaN(bounds.fLeft)) {
return false;
}
if (SkScalarIsNaN(bounds.fTop)) {
return false;
}
if (SkScalarIsNaN(bounds.fRight)) {
return false;
}
return !SkScalarIsNaN(bounds.fBottom);
}
bool ValidConic(const SkDConic& conic) {
for (int index = 0; index < SkDConic::kPointCount; ++index) {
if (!ValidPoint(conic[index])) {
return false;
}
}
if (SkDoubleIsNaN(conic.fWeight)) {
return false;
}
return true;
}
bool ValidCubic(const SkDCubic& cubic) {
for (int index = 0; index < 4; ++index) {
if (!ValidPoint(cubic[index])) {
return false;
}
}
return true;
}
bool ValidLine(const SkDLine& line) {
for (int index = 0; index < 2; ++index) {
if (!ValidPoint(line[index])) {
return false;
}
}
return true;
}
bool ValidPoint(const SkDPoint& pt) {
if (SkDoubleIsNaN(pt.fX)) {
return false;
}
return !SkDoubleIsNaN(pt.fY);
}
bool ValidPoints(const SkPoint* pts, int count) {
for (int index = 0; index < count; ++index) {
if (SkScalarIsNaN(pts[index].fX)) {
return false;
}
if (SkScalarIsNaN(pts[index].fY)) {
return false;
}
}
return true;
}
bool ValidQuad(const SkDQuad& quad) {
for (int index = 0; index < 3; ++index) {
if (!ValidPoint(quad[index])) {
return false;
}
}
return true;
}
bool ValidVector(const SkDVector& v) {
if (SkDoubleIsNaN(v.fX)) {
return false;
}
return !SkDoubleIsNaN(v.fY);
}
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