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skia2/samplecode/SamplePath.cpp
Mike Reed 66fa45616c identify interesting cubic points 
Bug: skia:
Change-Id: Ib649fe2c487c4f0183c2e7e5f5aadd7381a865ba
Reviewed-on: https://skia-review.googlesource.com/117623
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
2018-04-10 11:12:22 +00:00

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/*
* 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 "SampleCode.h"
#include "SkAnimTimer.h"
#include "SkView.h"
#include "SkBitmap.h"
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "SkGraphics.h"
#include "SkPath.h"
#include "SkRegion.h"
#include "SkShader.h"
#include "SkUtils.h"
#include "SkColorPriv.h"
#include "SkColorFilter.h"
#include "SkParsePath.h"
#include "SkTime.h"
#include "SkTypeface.h"
#include "SkGeometry.h"
#include <stdlib.h>
// http://code.google.com/p/skia/issues/detail?id=32
static void test_cubic() {
SkPoint src[4] = {
{ 556.25000f, 523.03003f },
{ 556.23999f, 522.96002f },
{ 556.21997f, 522.89001f },
{ 556.21997f, 522.82001f }
};
SkPoint dst[11];
dst[10].set(42, -42); // one past the end, that we don't clobber these
SkScalar tval[] = { 0.33333334f, 0.99999994f };
SkChopCubicAt(src, dst, tval, 2);
#if 0
for (int i = 0; i < 11; i++) {
SkDebugf("--- %d [%g %g]\n", i, dst[i].fX, dst[i].fY);
}
#endif
}
static void test_cubic2() {
const char* str = "M2242 -590088L-377758 9.94099e+07L-377758 9.94099e+07L2242 -590088Z";
SkPath path;
SkParsePath::FromSVGString(str, &path);
{
SkRect r = path.getBounds();
SkIRect ir;
r.round(&ir);
SkDebugf("[%g %g %g %g] [%x %x %x %x]\n",
SkScalarToDouble(r.fLeft), SkScalarToDouble(r.fTop),
SkScalarToDouble(r.fRight), SkScalarToDouble(r.fBottom),
ir.fLeft, ir.fTop, ir.fRight, ir.fBottom);
}
SkBitmap bitmap;
bitmap.allocN32Pixels(300, 200);
SkCanvas canvas(bitmap);
SkPaint paint;
paint.setAntiAlias(true);
canvas.drawPath(path, paint);
}
class PathView : public SampleView {
SkScalar fPrevSecs;
public:
SkScalar fDStroke, fStroke, fMinStroke, fMaxStroke;
SkPath fPath[6];
bool fShowHairline;
bool fOnce;
PathView() {
fPrevSecs = 0;
fOnce = false;
}
void init() {
if (fOnce) {
return;
}
fOnce = true;
test_cubic();
test_cubic2();
fShowHairline = false;
fDStroke = 1;
fStroke = 10;
fMinStroke = 10;
fMaxStroke = 180;
const SkScalar V = 85;
fPath[0].moveTo(40, 70);
fPath[0].lineTo(70, 70 + SK_ScalarHalf);
fPath[0].lineTo(110, 70);
fPath[1].moveTo(40, 70);
fPath[1].lineTo(70, 70 - SK_ScalarHalf);
fPath[1].lineTo(110, 70);
fPath[2].moveTo(V, V);
fPath[2].lineTo(50, V);
fPath[2].lineTo(50, 50);
fPath[3].moveTo(50, 50);
fPath[3].lineTo(50, V);
fPath[3].lineTo(V, V);
fPath[4].moveTo(50, 50);
fPath[4].lineTo(50, V);
fPath[4].lineTo(52, 50);
fPath[5].moveTo(52, 50);
fPath[5].lineTo(50, V);
fPath[5].lineTo(50, 50);
this->setBGColor(0xFFDDDDDD);
}
protected:
// overrides from SkEventSink
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "Paths");
return true;
}
return this->INHERITED::onQuery(evt);
}
void drawPath(SkCanvas* canvas, const SkPath& path, SkPaint::Join j) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeJoin(j);
paint.setStrokeWidth(fStroke);
if (fShowHairline) {
SkPath fill;
paint.getFillPath(path, &fill);
paint.setStrokeWidth(0);
canvas->drawPath(fill, paint);
} else {
canvas->drawPath(path, paint);
}
paint.setColor(SK_ColorRED);
paint.setStrokeWidth(0);
canvas->drawPath(path, paint);
}
void onDrawContent(SkCanvas* canvas) override {
this->init();
canvas->translate(50, 50);
static const SkPaint::Join gJoins[] = {
SkPaint::kBevel_Join,
SkPaint::kMiter_Join,
SkPaint::kRound_Join
};
for (size_t i = 0; i < SK_ARRAY_COUNT(gJoins); i++) {
canvas->save();
for (size_t j = 0; j < SK_ARRAY_COUNT(fPath); j++) {
this->drawPath(canvas, fPath[j], gJoins[i]);
canvas->translate(200, 0);
}
canvas->restore();
canvas->translate(0, 200);
}
}
bool onAnimate(const SkAnimTimer& timer) override {
SkScalar currSecs = timer.scaled(100);
SkScalar delta = currSecs - fPrevSecs;
fPrevSecs = currSecs;
fStroke += fDStroke * delta;
if (fStroke > fMaxStroke || fStroke < fMinStroke) {
fDStroke = -fDStroke;
}
return true;
}
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
fShowHairline = !fShowHairline;
return this->INHERITED::onFindClickHandler(x, y, modi);
}
private:
typedef SampleView INHERITED;
};
DEF_SAMPLE( return new PathView; )
//////////////////////////////////////////////////////////////////////////////
#include "SkCornerPathEffect.h"
#include "SkRandom.h"
class ArcToView : public SampleView {
bool fDoFrame, fDoCorner, fDoConic;
SkPaint fPtsPaint, fSkeletonPaint, fCornerPaint;
public:
enum {
N = 4
};
SkPoint fPts[N];
ArcToView()
: fDoFrame(false), fDoCorner(false), fDoConic(false)
{
SkRandom rand;
for (int i = 0; i < N; ++i) {
fPts[i].fX = 20 + rand.nextUScalar1() * 640;
fPts[i].fY = 20 + rand.nextUScalar1() * 480;
}
const SkScalar rad = 50;
fPtsPaint.setAntiAlias(true);
fPtsPaint.setStrokeWidth(15);
fPtsPaint.setStrokeCap(SkPaint::kRound_Cap);
fCornerPaint.setAntiAlias(true);
fCornerPaint.setStyle(SkPaint::kStroke_Style);
fCornerPaint.setStrokeWidth(13);
fCornerPaint.setColor(SK_ColorGREEN);
fCornerPaint.setPathEffect(SkCornerPathEffect::Make(rad*2));
fSkeletonPaint.setAntiAlias(true);
fSkeletonPaint.setStyle(SkPaint::kStroke_Style);
fSkeletonPaint.setColor(SK_ColorRED);
}
void toggle(bool& value) {
value = !value;
}
protected:
// overrides from SkEventSink
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "ArcTo");
return true;
}
SkUnichar uni;
if (SampleCode::CharQ(*evt, &uni)) {
switch (uni) {
case '1': this->toggle(fDoFrame); return true;
case '2': this->toggle(fDoCorner); return true;
case '3': this->toggle(fDoConic); return true;
default: break;
}
}
return this->INHERITED::onQuery(evt);
}
void makePath(SkPath* path) {
path->moveTo(fPts[0]);
for (int i = 1; i < N; ++i) {
path->lineTo(fPts[i]);
}
if (!fDoFrame) {
path->close();
}
}
void onDrawContent(SkCanvas* canvas) override {
canvas->drawPoints(SkCanvas::kPoints_PointMode, N, fPts, fPtsPaint);
SkPath path;
this->makePath(&path);
if (fDoCorner) {
canvas->drawPath(path, fCornerPaint);
}
canvas->drawPath(path, fSkeletonPaint);
}
bool onClick(Click* click) override {
int32_t index;
if (click->fMeta.findS32("index", &index)) {
SkASSERT((unsigned)index < N);
fPts[index] = click->fCurr;
return true;
}
return false;
}
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
const SkScalar tol = 4;
const SkRect r = SkRect::MakeXYWH(x - tol, y - tol, tol * 2, tol * 2);
for (int i = 0; i < N; ++i) {
if (r.intersects(SkRect::MakeXYWH(fPts[i].fX, fPts[i].fY, 1, 1))) {
Click* click = new Click(this);
click->fMeta.setS32("index", i);
return click;
}
}
return this->INHERITED::onFindClickHandler(x, y, modi);
}
private:
typedef SampleView INHERITED;
};
DEF_SAMPLE( return new ArcToView; )
/////////////
class FatStroke : public SampleView {
bool fClosed, fShowStroke, fShowHidden, fShowSkeleton;
int fJoinType, fCapType;
float fWidth = 30;
SkPaint fPtsPaint, fHiddenPaint, fSkeletonPaint, fStrokePaint;
public:
enum {
N = 4
};
SkPoint fPts[N];
FatStroke() : fClosed(false), fShowStroke(true), fShowHidden(false), fShowSkeleton(true),
fJoinType(0), fCapType(0)
{
SkRandom rand;
for (int i = 0; i < N; ++i) {
fPts[i].fX = 20 + rand.nextUScalar1() * 640;
fPts[i].fY = 20 + rand.nextUScalar1() * 480;
}
fPtsPaint.setAntiAlias(true);
fPtsPaint.setStrokeWidth(10);
fPtsPaint.setStrokeCap(SkPaint::kRound_Cap);
fHiddenPaint.setAntiAlias(true);
fHiddenPaint.setStyle(SkPaint::kStroke_Style);
fHiddenPaint.setColor(0xFF0000FF);
fStrokePaint.setAntiAlias(true);
fStrokePaint.setStyle(SkPaint::kStroke_Style);
fStrokePaint.setStrokeWidth(50);
fStrokePaint.setColor(0x8000FF00);
fSkeletonPaint.setAntiAlias(true);
fSkeletonPaint.setStyle(SkPaint::kStroke_Style);
fSkeletonPaint.setColor(SK_ColorRED);
}
void toggle(bool& value) {
value = !value;
}
void toggle3(int& value) {
value = (value + 1) % 3;
}
protected:
// overrides from SkEventSink
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "FatStroke");
return true;
}
SkUnichar uni;
if (SampleCode::CharQ(*evt, &uni)) {
switch (uni) {
case '1': this->toggle(fShowSkeleton); return true;
case '2': this->toggle(fShowStroke); return true;
case '3': this->toggle(fShowHidden); return true;
case '4': this->toggle3(fJoinType); return true;
case '5': this->toggle3(fCapType); return true;
case '6': this->toggle(fClosed); return true;
case '-': fWidth -= 5; return true;
case '=': fWidth += 5; return true;
default: break;
}
}
return this->INHERITED::onQuery(evt);
}
void makePath(SkPath* path) {
path->moveTo(fPts[0]);
for (int i = 1; i < N; ++i) {
path->lineTo(fPts[i]);
}
if (fClosed) {
path->close();
}
}
void onDrawContent(SkCanvas* canvas) override {
canvas->drawColor(0xFFEEEEEE);
SkPath path;
this->makePath(&path);
fStrokePaint.setStrokeWidth(fWidth);
fStrokePaint.setStrokeJoin((SkPaint::Join)fJoinType);
fStrokePaint.setStrokeCap((SkPaint::Cap)fCapType);
if (fShowStroke) {
canvas->drawPath(path, fStrokePaint);
}
if (fShowHidden) {
SkPath hidden;
fStrokePaint.getFillPath(path, &hidden);
canvas->drawPath(hidden, fHiddenPaint);
}
if (fShowSkeleton) {
canvas->drawPath(path, fSkeletonPaint);
}
canvas->drawPoints(SkCanvas::kPoints_PointMode, N, fPts, fPtsPaint);
}
bool onClick(Click* click) override {
int32_t index;
if (click->fMeta.findS32("index", &index)) {
SkASSERT((unsigned)index < N);
fPts[index] = click->fCurr;
return true;
}
return false;
}
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
const SkScalar tol = 4;
const SkRect r = SkRect::MakeXYWH(x - tol, y - tol, tol * 2, tol * 2);
for (int i = 0; i < N; ++i) {
if (r.intersects(SkRect::MakeXYWH(fPts[i].fX, fPts[i].fY, 1, 1))) {
Click* click = new Click(this);
click->fMeta.setS32("index", i);
return click;
}
}
return this->INHERITED::onFindClickHandler(x, y, modi);
}
private:
typedef SampleView INHERITED;
};
DEF_SAMPLE( return new FatStroke; )
static int compute_parallel_to_base(const SkPoint pts[4], SkScalar t[2]) {
// F = At^3 + Bt^2 + Ct + D
SkVector A = pts[3] - pts[0] + (pts[1] - pts[2]) * 3.0f;
SkVector B = (pts[0] - pts[1] - pts[1] + pts[2]) * 3.0f;
SkVector C = (pts[1] - pts[0]) * 3.0f;
SkVector DA = pts[3] - pts[0];
// F' = 3At^2 + 2Bt + C
SkScalar a = 3 * A.cross(DA);
SkScalar b = 2 * B.cross(DA);
SkScalar c = C.cross(DA);
int n = SkFindUnitQuadRoots(a, b, c, t);
SkString str;
for (int i = 0; i < n; ++i) {
str.appendf(" %g", t[i]);
}
SkDebugf("roots %s\n", str.c_str());
return n;
}
class CubicCurve : public SampleView {
public:
enum {
N = 4
};
SkPoint fPts[N];
CubicCurve() {
SkRandom rand;
for (int i = 0; i < N; ++i) {
fPts[i].fX = 20 + rand.nextUScalar1() * 640;
fPts[i].fY = 20 + rand.nextUScalar1() * 480;
}
}
protected:
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "CubicCurve");
return true;
}
return this->INHERITED::onQuery(evt);
}
void onDrawContent(SkCanvas* canvas) override {
SkPaint paint;
paint.setAntiAlias(true);
{
SkPath path;
path.moveTo(fPts[0]);
path.cubicTo(fPts[1], fPts[2], fPts[3]);
paint.setStyle(SkPaint::kStroke_Style);
canvas->drawPath(path, paint);
}
{
paint.setColor(SK_ColorRED);
SkScalar t[2];
int n = compute_parallel_to_base(fPts, t);
SkPoint loc;
SkVector tan;
for (int i = 0; i < n; ++i) {
SkEvalCubicAt(fPts, t[i], &loc, &tan, nullptr);
tan.setLength(30);
canvas->drawLine(loc - tan, loc + tan, paint);
}
paint.setStrokeWidth(0.5f);
canvas->drawLine(fPts[0], fPts[3], paint);
paint.setColor(SK_ColorBLUE);
paint.setStrokeWidth(6);
SkEvalCubicAt(fPts, 0.5f, &loc, nullptr, nullptr);
canvas->drawPoint(loc, paint);
paint.setColor(0xFF008800);
SkEvalCubicAt(fPts, 1.0f/3, &loc, nullptr, nullptr);
canvas->drawPoint(loc, paint);
SkEvalCubicAt(fPts, 2.0f/3, &loc, nullptr, nullptr);
canvas->drawPoint(loc, paint);
// n = SkFindCubicInflections(fPts, t);
// printf("inflections %d %g %g\n", n, t[0], t[1]);
}
{
paint.setStyle(SkPaint::kFill_Style);
paint.setColor(SK_ColorRED);
for (SkPoint p : fPts) {
canvas->drawCircle(p.fX, p.fY, 8, paint);
}
}
}
bool onClick(Click* click) override {
int32_t index;
if (click->fMeta.findS32("index", &index)) {
SkASSERT((unsigned)index < N);
fPts[index] = click->fCurr;
return true;
}
return false;
}
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
const SkScalar tol = 8;
const SkRect r = SkRect::MakeXYWH(x - tol, y - tol, tol * 2, tol * 2);
for (int i = 0; i < N; ++i) {
if (r.intersects(SkRect::MakeXYWH(fPts[i].fX, fPts[i].fY, 1, 1))) {
Click* click = new Click(this);
click->fMeta.setS32("index", i);
return click;
}
}
return this->INHERITED::onFindClickHandler(x, y, modi);
}
private:
typedef SampleView INHERITED;
};
DEF_SAMPLE( return new CubicCurve; )
static SkPoint lerp(SkPoint a, SkPoint b, float t) {
return a * (1 - t) + b * t;
}
class CubicCurve2 : public SampleView {
public:
enum {
N = 7
};
SkPoint fPts[N];
SkPoint* fQuad = fPts + 4;
SkScalar fT = 0.5f;
bool fShowSub = false;
CubicCurve2() {
fPts[0] = { 90, 300 };
fPts[1] = { 30, 60 };
fPts[2] = { 250, 30 };
fPts[3] = { 350, 200 };
fQuad[0] = fPts[0] + SkVector{ 300, 0};
fQuad[1] = fPts[1] + SkVector{ 300, 0};
fQuad[2] = fPts[2] + SkVector{ 300, 0};
}
protected:
bool onQuery(SkEvent* evt) override {
if (SampleCode::TitleQ(*evt)) {
SampleCode::TitleR(evt, "CubicCurve2");
return true;
}
SkUnichar uni;
if (SampleCode::CharQ(*evt, &uni)) {
switch (uni) {
case 's': fShowSub = !fShowSub; break;
case '-': fT -= 1.0f / 32; break;
case '=': fT += 1.0f / 32; break;
default: goto DONE;
}
fT = std::min(1.0f, std::max(0.0f, fT));
return true;
}
DONE:
return this->INHERITED::onQuery(evt);
}
void showFrame(SkCanvas* canvas, const SkPoint pts[], int count, const SkPaint& p) {
SkPaint paint(p);
SkPoint storage[3 + 2 + 1];
SkPoint* tmp = storage;
const SkPoint* prev = pts;
int n = count;
for (int n = count; n > 0; --n) {
for (int i = 0; i < n; ++i) {
canvas->drawLine(prev[i], prev[i+1], paint);
tmp[i] = lerp(prev[i], prev[i+1], fT);
}
prev = tmp;
tmp += n;
}
paint.setColor(SK_ColorBLUE);
paint.setStyle(SkPaint::kFill_Style);
n = tmp - storage;
for (int i = 0; i < n; ++i) {
canvas->drawCircle(storage[i].fX, storage[i].fY, 4, paint);
}
}
void onDrawContent(SkCanvas* canvas) override {
SkPaint paint;
paint.setAntiAlias(true);
{
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(fPts[0]);
path.cubicTo(fPts[1], fPts[2], fPts[3]);
path.moveTo(fQuad[0]);
path.quadTo(fQuad[1], fQuad[2]);
canvas->drawPath(path, paint);
}
if (fShowSub) {
paint.setColor(SK_ColorRED);
paint.setStrokeWidth(1.7f);
this->showFrame(canvas, fPts, 3, paint);
this->showFrame(canvas, fQuad, 2, paint);
SkString str;
str.printf("t = %g", fT);
paint.setColor(SK_ColorBLACK);
paint.setStyle(SkPaint::kFill_Style);
paint.setTextSize(20);
canvas->drawText(str.c_str(), str.size(), 20, 20, paint);
}
paint.setStyle(SkPaint::kFill_Style);
paint.setColor(SK_ColorRED);
for (SkPoint p : fPts) {
canvas->drawCircle(p.fX, p.fY, 7, paint);
}
}
bool onClick(Click* click) override {
int32_t index;
if (click->fMeta.findS32("index", &index)) {
SkASSERT((unsigned)index < N);
fPts[index] = click->fCurr;
return true;
}
return false;
}
SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
const SkScalar tol = 8;
const SkRect r = SkRect::MakeXYWH(x - tol, y - tol, tol * 2, tol * 2);
for (int i = 0; i < N; ++i) {
if (r.intersects(SkRect::MakeXYWH(fPts[i].fX, fPts[i].fY, 1, 1))) {
Click* click = new Click(this);
click->fMeta.setS32("index", i);
return click;
}
}
return this->INHERITED::onFindClickHandler(x, y, modi);
}
private:
typedef SampleView INHERITED;
};
DEF_SAMPLE( return new CubicCurve2; )
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