samplecode/SampleSlides.cpp - platform/external/skia - Gitiles

 /*
  * 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 "Sample.h"
 #include "SkBlurMask.h"
 #include "SkBlurMaskFilter.h"
 #include "SkCanvas.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkGradientShader.h"
 #include "SkPaint.h"
 #include "SkVertices.h"

 #include "sk_tool_utils.h"

 #define BG_COLOR    0xFFDDDDDD

 typedef void (*SlideProc)(SkCanvas*);

 ///////////////////////////////////////////////////////////////////////////////

 #include "Sk1DPathEffect.h"
 #include "Sk2DPathEffect.h"
 #include "SkCornerPathEffect.h"
 #include "SkDashPathEffect.h"
 #include "SkDiscretePathEffect.h"

 static void compose_pe(SkPaint* paint) {
     SkPathEffect* pe = paint->getPathEffect();
     sk_sp<SkPathEffect> corner = SkCornerPathEffect::Make(25);
     sk_sp<SkPathEffect> compose;
     if (pe) {
         compose = SkPathEffect::MakeCompose(sk_ref_sp(pe), corner);
     } else {
         compose = corner;
     }
     paint->setPathEffect(compose);
 }

 static void hair_pe(SkPaint* paint) {
     paint->setStrokeWidth(0);
 }

 static void hair2_pe(SkPaint* paint) {
     paint->setStrokeWidth(0);
     compose_pe(paint);
 }

 static void stroke_pe(SkPaint* paint) {
     paint->setStrokeWidth(12);
     compose_pe(paint);
 }

 static void dash_pe(SkPaint* paint) {
     SkScalar inter[] = { 20, 10, 10, 10 };
     paint->setStrokeWidth(12);
     paint->setPathEffect(SkDashPathEffect::Make(inter, SK_ARRAY_COUNT(inter), 0));
     compose_pe(paint);
 }

 static const int gXY[] = {
 4, 0, 0, -4, 8, -4, 12, 0, 8, 4, 0, 4
 };

 static void scale(SkPath* path, SkScalar scale) {
     SkMatrix m;
     m.setScale(scale, scale);
     path->transform(m);
 }

 static void one_d_pe(SkPaint* paint) {
     SkPath  path;
     path.moveTo(SkIntToScalar(gXY[0]), SkIntToScalar(gXY[1]));
     for (unsigned i = 2; i < SK_ARRAY_COUNT(gXY); i += 2)
         path.lineTo(SkIntToScalar(gXY[i]), SkIntToScalar(gXY[i+1]));
     path.close();
     path.offset(SkIntToScalar(-6), 0);
     scale(&path, 1.5f);

     paint->setPathEffect(SkPath1DPathEffect::Make(path, SkIntToScalar(21), 0,
                                                   SkPath1DPathEffect::kRotate_Style));
     compose_pe(paint);
 }

 typedef void (*PE_Proc)(SkPaint*);
 static const PE_Proc gPE[] = { hair_pe, hair2_pe, stroke_pe, dash_pe, one_d_pe };

 static void fill_pe(SkPaint* paint) {
     paint->setStyle(SkPaint::kFill_Style);
     paint->setPathEffect(nullptr);
 }

 static void discrete_pe(SkPaint* paint) {
     paint->setPathEffect(SkDiscretePathEffect::Make(10, 4));
 }

 static sk_sp<SkPathEffect> MakeTileEffect() {
     SkMatrix m;
     m.setScale(SkIntToScalar(12), SkIntToScalar(12));

     SkPath path;
     path.addCircle(0, 0, SkIntToScalar(5));

     return SkPath2DPathEffect::Make(m, path);
 }

 static void tile_pe(SkPaint* paint) {
     paint->setPathEffect(MakeTileEffect());
 }

 static const PE_Proc gPE2[] = { fill_pe, discrete_pe, tile_pe };

 static void patheffect_slide(SkCanvas* canvas) {
     SkPaint paint;
     paint.setAntiAlias(true);
     paint.setStyle(SkPaint::kStroke_Style);

     SkPath path;
     path.moveTo(20, 20);
     path.lineTo(70, 120);
     path.lineTo(120, 30);
     path.lineTo(170, 80);
     path.lineTo(240, 50);

     size_t i;
     canvas->save();
     for (i = 0; i < SK_ARRAY_COUNT(gPE); i++) {
         gPE[i](&paint);
         canvas->drawPath(path, paint);
         canvas->translate(0, 75);
     }
     canvas->restore();

     path.reset();
     SkRect r = { 0, 0, 250, 120 };
     path.addOval(r, SkPath::kCW_Direction);
     r.inset(50, 50);
     path.addRect(r, SkPath::kCCW_Direction);

     canvas->translate(320, 20);
     for (i = 0; i < SK_ARRAY_COUNT(gPE2); i++) {
         gPE2[i](&paint);
         canvas->drawPath(path, paint);
         canvas->translate(0, 160);
     }
 }

 ///////////////////////////////////////////////////////////////////////////////

 #include "SkGradientShader.h"

 struct GradData {
     int             fCount;
     const SkColor*  fColors;
     const SkScalar* fPos;
 };

 static const SkColor gColors[] = {
 SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorWHITE, SK_ColorBLACK
 };
 static const SkScalar gPos0[] = { 0, SK_Scalar1 };
 static const SkScalar gPos1[] = { SK_Scalar1/4, SK_Scalar1*3/4 };
 static const SkScalar gPos2[] = {
 0, SK_Scalar1/8, SK_Scalar1/2, SK_Scalar1*7/8, SK_Scalar1
 };

 static const GradData gGradData[] = {
 { 2, gColors, nullptr },
 { 2, gColors, gPos0 },
 { 2, gColors, gPos1 },
 { 5, gColors, nullptr },
 { 5, gColors, gPos2 }
 };

 static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
     return SkGradientShader::MakeLinear(pts, data.fColors, data.fPos, data.fCount, tm);
 }

 static sk_sp<SkShader> MakeRadial(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
     SkPoint center;
     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
                SkScalarAve(pts[0].fY, pts[1].fY));
     return SkGradientShader::MakeRadial(center, center.fX, data.fColors,
                                           data.fPos, data.fCount, tm);
 }

 static sk_sp<SkShader> MakeSweep(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
     SkPoint center;
     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
                SkScalarAve(pts[0].fY, pts[1].fY));
     return SkGradientShader::MakeSweep(center.fX, center.fY, data.fColors, data.fPos, data.fCount);
 }

 static sk_sp<SkShader> Make2Conical(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
     SkPoint center0, center1;
     center0.set(SkScalarAve(pts[0].fX, pts[1].fX),
                 SkScalarAve(pts[0].fY, pts[1].fY));
     center1.set(SkScalarInterp(pts[0].fX, pts[1].fX, SkIntToScalar(3)/5),
                 SkScalarInterp(pts[0].fY, pts[1].fY, SkIntToScalar(1)/4));
     return SkGradientShader::MakeTwoPointConical(center1, (pts[1].fX - pts[0].fX) / 7,
                                                   center0, (pts[1].fX - pts[0].fX) / 2,
                                                   data.fColors, data.fPos, data.fCount, tm);
 }

 typedef sk_sp<SkShader> (*GradMaker)(const SkPoint pts[2], const GradData&, SkShader::TileMode);
 static const GradMaker gGradMakers[] = {
     MakeLinear, MakeRadial, MakeSweep, Make2Conical
 };

 static void gradient_slide(SkCanvas* canvas) {
     SkPoint pts[2] = {
         { 0, 0 },
         { SkIntToScalar(100), SkIntToScalar(100) }
     };
     SkShader::TileMode tm = SkShader::kClamp_TileMode;
     SkRect r = { 0, 0, SkIntToScalar(100), SkIntToScalar(100) };
     SkPaint paint;
     paint.setAntiAlias(true);
     paint.setDither(true);

     canvas->translate(SkIntToScalar(20), SkIntToScalar(10));
     for (size_t i = 0; i < SK_ARRAY_COUNT(gGradData); i++) {
         canvas->save();
         for (size_t j = 0; j < SK_ARRAY_COUNT(gGradMakers); j++) {
             paint.setShader(gGradMakers[j](pts, gGradData[i], tm));
             canvas->drawRect(r, paint);
             canvas->translate(0, SkIntToScalar(120));
         }
         canvas->restore();
         canvas->translate(SkIntToScalar(120), 0);
     }
 }

 ///////////////////////////////////////////////////////////////////////////////

 #include "SkPathMeasure.h"

 static SkScalar getpathlen(const SkPath& path) {
     SkPathMeasure   meas(path, false);
     return meas.getLength();
 }

 static void textonpath_slide(SkCanvas* canvas) {
     const char* text = "Displacement";
     size_t len =strlen(text);
     SkPath path;
     path.moveTo(100, 300);
     path.quadTo(300, 100, 500, 300);
     path.offset(0, -100);

     SkPaint paint;
     paint.setAntiAlias(true);
     paint.setTextSize(40);

     paint.setStyle(SkPaint::kStroke_Style);
     canvas->drawPath(path, paint);
     paint.setStyle(SkPaint::kFill_Style);

     SkScalar x = 50;
     paint.setColor(0xFF008800);
     canvas->drawTextOnPathHV(text, len, path,
                              x, paint.getTextSize()*2/3, paint);
     paint.setColor(SK_ColorRED);
     canvas->drawTextOnPathHV(text, len, path,
                              x + 60, 0, paint);
     paint.setColor(SK_ColorBLUE);
     canvas->drawTextOnPathHV(text, len, path,
                              x + 120, -paint.getTextSize()*2/3, paint);

     path.offset(0, 200);
     paint.setTextAlign(SkPaint::kRight_Align);

     text = "Matrices";
     len = strlen(text);
     SkScalar pathLen = getpathlen(path);
     SkMatrix matrix;

     paint.setColor(SK_ColorBLACK);
     paint.setStyle(SkPaint::kStroke_Style);
     canvas->drawPath(path, paint);
     paint.setStyle(SkPaint::kFill_Style);

     paint.setTextSize(50);
     canvas->drawTextOnPath(text, len, path, nullptr, paint);

     paint.setColor(SK_ColorRED);
     matrix.setScale(-SK_Scalar1, SK_Scalar1);
     matrix.postTranslate(pathLen, 0);
     canvas->drawTextOnPath(text, len, path, &matrix, paint);

     paint.setColor(SK_ColorBLUE);
     matrix.setScale(SK_Scalar1, -SK_Scalar1);
     canvas->drawTextOnPath(text, len, path, &matrix, paint);

     paint.setColor(0xFF008800);
     matrix.setScale(-SK_Scalar1, -SK_Scalar1);
     matrix.postTranslate(pathLen, 0);
     canvas->drawTextOnPath(text, len, path, &matrix, paint);
 }

 ///////////////////////////////////////////////////////////////////////////////

 #include "DecodeFile.h"
 #include "SkOSFile.h"
 #include "SkRandom.h"
 #include "SkStream.h"

 static sk_sp<SkShader> make_shader0(SkIPoint* size) {
     SkBitmap    bm;

     decode_file("/skimages/logo.gif", &bm);
     size->set(bm.width(), bm.height());
     return SkShader::MakeBitmapShader(bm, SkShader::kClamp_TileMode,
                                         SkShader::kClamp_TileMode);
 }

 static sk_sp<SkShader> make_shader1(const SkIPoint& size) {
     SkPoint pts[] = { { 0, 0 },
                       { SkIntToScalar(size.fX), SkIntToScalar(size.fY) } };
     SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorRED };
     return SkGradientShader::MakeLinear(pts, colors, nullptr,
                                           SK_ARRAY_COUNT(colors), SkShader::kMirror_TileMode);
 }

 class Rec {
 public:
     SkVertices::VertexMode  fMode;
     int                     fCount;
     SkPoint*                fVerts;
     SkPoint*                fTexs;

     Rec() : fCount(0), fVerts(nullptr), fTexs(nullptr) {}
     ~Rec() { delete[] fVerts; delete[] fTexs; }
 };

 static void make_tris(Rec* rec) {
     int n = 10;
     SkRandom    rand;

     rec->fMode = SkVertices::kTriangles_VertexMode;
     rec->fCount = n * 3;
     rec->fVerts = new SkPoint[rec->fCount];

     for (int i = 0; i < n; i++) {
         SkPoint* v = &rec->fVerts[i*3];
         for (int j = 0; j < 3; j++) {
             v[j].set(rand.nextUScalar1() * 250, rand.nextUScalar1() * 250);
         }
     }
 }

 static void make_fan(Rec* rec, int texWidth, int texHeight) {
     const SkScalar tx = SkIntToScalar(texWidth);
     const SkScalar ty = SkIntToScalar(texHeight);
     const int n = 24;

     rec->fMode = SkVertices::kTriangleFan_VertexMode;
     rec->fCount = n + 2;
     rec->fVerts = new SkPoint[rec->fCount];
     rec->fTexs  = new SkPoint[rec->fCount];

     SkPoint* v = rec->fVerts;
     SkPoint* t = rec->fTexs;

     v[0].set(0, 0);
     t[0].set(0, 0);
     for (int i = 0; i < n; i++) {
         SkScalar cos;
         SkScalar sin = SkScalarSinCos(SK_ScalarPI * 2 * i / n, &cos);
         v[i+1].set(cos, sin);
         t[i+1].set(i*tx/n, ty);
     }
     v[n+1] = v[1];
     t[n+1].set(tx, ty);

     SkMatrix m;
     m.setScale(SkIntToScalar(100), SkIntToScalar(100));
     m.postTranslate(SkIntToScalar(110), SkIntToScalar(110));
     m.mapPoints(v, rec->fCount);
 }

 static void make_strip(Rec* rec, int texWidth, int texHeight) {
     const SkScalar tx = SkIntToScalar(texWidth);
     const SkScalar ty = SkIntToScalar(texHeight);
     const int n = 24;

     rec->fMode = SkVertices::kTriangleStrip_VertexMode;
     rec->fCount = 2 * (n + 1);
     rec->fVerts = new SkPoint[rec->fCount];
     rec->fTexs  = new SkPoint[rec->fCount];

     SkPoint* v = rec->fVerts;
     SkPoint* t = rec->fTexs;

     for (int i = 0; i < n; i++) {
         SkScalar cos;
         SkScalar sin = SkScalarSinCos(SK_ScalarPI * 2 * i / n, &cos);
         v[i*2 + 0].set(cos/2, sin/2);
         v[i*2 + 1].set(cos, sin);

         t[i*2 + 0].set(tx * i / n, ty);
         t[i*2 + 1].set(tx * i / n, 0);
     }
     v[2*n + 0] = v[0];
     v[2*n + 1] = v[1];

     t[2*n + 0].set(tx, ty);
     t[2*n + 1].set(tx, 0);

     SkMatrix m;
     m.setScale(SkIntToScalar(100), SkIntToScalar(100));
     m.postTranslate(SkIntToScalar(110), SkIntToScalar(110));
     m.mapPoints(v, rec->fCount);
 }

 static void mesh_slide(SkCanvas* canvas) {
     Rec fRecs[3];
     SkIPoint    size;

     auto fShader0 = make_shader0(&size);
     auto fShader1 = make_shader1(size);

     make_strip(&fRecs[0], size.fX, size.fY);
     make_fan(&fRecs[1], size.fX, size.fY);
     make_tris(&fRecs[2]);

     SkPaint paint;
     paint.setDither(true);
     paint.setFilterQuality(kLow_SkFilterQuality);

     for (size_t i = 0; i < SK_ARRAY_COUNT(fRecs); i++) {
         auto verts = SkVertices::MakeCopy(fRecs[i].fMode, fRecs[i].fCount,
                                           fRecs[i].fVerts, fRecs[i].fTexs, nullptr);
         canvas->save();

         paint.setShader(nullptr);
         canvas->drawVertices(verts, SkBlendMode::kModulate, paint);

         canvas->translate(SkIntToScalar(210), 0);

         paint.setShader(fShader0);
         canvas->drawVertices(verts, SkBlendMode::kModulate, paint);

         canvas->translate(SkIntToScalar(210), 0);

         paint.setShader(fShader1);
         canvas->drawVertices(verts, SkBlendMode::kModulate, paint);
         canvas->restore();

         canvas->translate(0, SkIntToScalar(250));
     }
 }

 ///////////////////////////////////////////////////////////////////////////////

 #include "SkTypeface.h"

 ///////////////////////////////////////////////////////////////////////////////

 #include "SkImageEncoder.h"

 static const SlideProc gProc[] = {
     patheffect_slide,
     gradient_slide,
     textonpath_slide,
     mesh_slide,
 };

 class SlideView : public Sample {
     int fIndex;
     bool fOnce;
 public:
     SlideView() {
         fOnce = false;
     }

     void init() {
         if (fOnce) {
             return;
         }
         fOnce = true;

         fIndex = 0;

         SkBitmap bm;
         bm.allocN32Pixels(1024, 768);
         SkCanvas canvas(bm);
         SkScalar s = SkIntToScalar(1024) / 640;
         canvas.scale(s, s);
         for (size_t i = 0; i < SK_ARRAY_COUNT(gProc); i++) {
             canvas.save();
             canvas.drawColor(BG_COLOR);
             gProc[i](&canvas);
             canvas.restore();
             SkString str;
             str.printf("/skimages/slide_" SK_SIZE_T_SPECIFIER ".png", i);
             sk_tool_utils::EncodeImageToFile(str.c_str(), bm, SkEncodedImageFormat::kPNG, 100);
         }
         this->setBGColor(BG_COLOR);
     }

 protected:
     bool onQuery(Sample::Event* evt) override {
         if (Sample::TitleQ(*evt)) {
             Sample::TitleR(evt, "Slides");
             return true;
         }
         return this->INHERITED::onQuery(evt);
     }

     void onDrawContent(SkCanvas* canvas) override {
         this->init();
         gProc[fIndex](canvas);
     }

     Sample::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned) override {
         this->init();
         fIndex = (fIndex + 1) % SK_ARRAY_COUNT(gProc);
         return nullptr;
     }

 private:
     typedef Sample INHERITED;
 };

 //////////////////////////////////////////////////////////////////////////////

 DEF_SAMPLE( return new SlideView(); )
	/*
	* 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 "Sample.h"
	#include "SkBlurMask.h"
	#include "SkBlurMaskFilter.h"
	#include "SkCanvas.h"
	#include "SkReadBuffer.h"
	#include "SkWriteBuffer.h"
	#include "SkGradientShader.h"
	#include "SkPaint.h"
	#include "SkVertices.h"

	#include "sk_tool_utils.h"

	#define BG_COLOR 0xFFDDDDDD

	typedef void (SlideProc)(SkCanvas);

	///////////////////////////////////////////////////////////////////////////////

	#include "Sk1DPathEffect.h"
	#include "Sk2DPathEffect.h"
	#include "SkCornerPathEffect.h"
	#include "SkDashPathEffect.h"
	#include "SkDiscretePathEffect.h"

	static void compose_pe(SkPaint* paint) {
	SkPathEffect* pe = paint->getPathEffect();
	sk_sp<SkPathEffect> corner = SkCornerPathEffect::Make(25);
	sk_sp<SkPathEffect> compose;
	if (pe) {
	compose = SkPathEffect::MakeCompose(sk_ref_sp(pe), corner);
	} else {
	compose = corner;
	}
	paint->setPathEffect(compose);
	}

	static void hair_pe(SkPaint* paint) {
	paint->setStrokeWidth(0);
	}

	static void hair2_pe(SkPaint* paint) {
	paint->setStrokeWidth(0);
	compose_pe(paint);
	}

	static void stroke_pe(SkPaint* paint) {
	paint->setStrokeWidth(12);
	compose_pe(paint);
	}

	static void dash_pe(SkPaint* paint) {
	SkScalar inter[] = { 20, 10, 10, 10 };
	paint->setStrokeWidth(12);
	paint->setPathEffect(SkDashPathEffect::Make(inter, SK_ARRAY_COUNT(inter), 0));
	compose_pe(paint);
	}

	static const int gXY[] = {
	4, 0, 0, -4, 8, -4, 12, 0, 8, 4, 0, 4
	};

	static void scale(SkPath* path, SkScalar scale) {
	SkMatrix m;
	m.setScale(scale, scale);
	path->transform(m);
	}

	static void one_d_pe(SkPaint* paint) {
	SkPath path;
	path.moveTo(SkIntToScalar(gXY[0]), SkIntToScalar(gXY[1]));
	for (unsigned i = 2; i < SK_ARRAY_COUNT(gXY); i += 2)
	path.lineTo(SkIntToScalar(gXY[i]), SkIntToScalar(gXY[i+1]));
	path.close();
	path.offset(SkIntToScalar(-6), 0);
	scale(&path, 1.5f);

	paint->setPathEffect(SkPath1DPathEffect::Make(path, SkIntToScalar(21), 0,
	SkPath1DPathEffect::kRotate_Style));
	compose_pe(paint);
	}

	typedef void (PE_Proc)(SkPaint);
	static const PE_Proc gPE[] = { hair_pe, hair2_pe, stroke_pe, dash_pe, one_d_pe };

	static void fill_pe(SkPaint* paint) {
	paint->setStyle(SkPaint::kFill_Style);
	paint->setPathEffect(nullptr);
	}

	static void discrete_pe(SkPaint* paint) {
	paint->setPathEffect(SkDiscretePathEffect::Make(10, 4));
	}

	static sk_sp<SkPathEffect> MakeTileEffect() {
	SkMatrix m;
	m.setScale(SkIntToScalar(12), SkIntToScalar(12));

	SkPath path;
	path.addCircle(0, 0, SkIntToScalar(5));

	return SkPath2DPathEffect::Make(m, path);
	}

	static void tile_pe(SkPaint* paint) {
	paint->setPathEffect(MakeTileEffect());
	}

	static const PE_Proc gPE2[] = { fill_pe, discrete_pe, tile_pe };

	static void patheffect_slide(SkCanvas* canvas) {
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setStyle(SkPaint::kStroke_Style);

	SkPath path;
	path.moveTo(20, 20);
	path.lineTo(70, 120);
	path.lineTo(120, 30);
	path.lineTo(170, 80);
	path.lineTo(240, 50);

	size_t i;
	canvas->save();
	for (i = 0; i < SK_ARRAY_COUNT(gPE); i++) {
	gPE[i](&paint);
	canvas->drawPath(path, paint);
	canvas->translate(0, 75);
	}
	canvas->restore();

	path.reset();
	SkRect r = { 0, 0, 250, 120 };
	path.addOval(r, SkPath::kCW_Direction);
	r.inset(50, 50);
	path.addRect(r, SkPath::kCCW_Direction);

	canvas->translate(320, 20);
	for (i = 0; i < SK_ARRAY_COUNT(gPE2); i++) {
	gPE2[i](&paint);
	canvas->drawPath(path, paint);
	canvas->translate(0, 160);
	}
	}

	///////////////////////////////////////////////////////////////////////////////

	#include "SkGradientShader.h"

	struct GradData {
	int fCount;
	const SkColor* fColors;
	const SkScalar* fPos;
	};

	static const SkColor gColors[] = {
	SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorWHITE, SK_ColorBLACK
	};
	static const SkScalar gPos0[] = { 0, SK_Scalar1 };
	static const SkScalar gPos1[] = { SK_Scalar1/4, SK_Scalar1*3/4 };
	static const SkScalar gPos2[] = {
	0, SK_Scalar1/8, SK_Scalar1/2, SK_Scalar1*7/8, SK_Scalar1
	};

	static const GradData gGradData[] = {
	{ 2, gColors, nullptr },
	{ 2, gColors, gPos0 },
	{ 2, gColors, gPos1 },
	{ 5, gColors, nullptr },
	{ 5, gColors, gPos2 }
	};

	static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
	return SkGradientShader::MakeLinear(pts, data.fColors, data.fPos, data.fCount, tm);
	}

	static sk_sp<SkShader> MakeRadial(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
	SkPoint center;
	center.set(SkScalarAve(pts[0].fX, pts[1].fX),
	SkScalarAve(pts[0].fY, pts[1].fY));
	return SkGradientShader::MakeRadial(center, center.fX, data.fColors,
	data.fPos, data.fCount, tm);
	}

	static sk_sp<SkShader> MakeSweep(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
	SkPoint center;
	center.set(SkScalarAve(pts[0].fX, pts[1].fX),
	SkScalarAve(pts[0].fY, pts[1].fY));
	return SkGradientShader::MakeSweep(center.fX, center.fY, data.fColors, data.fPos, data.fCount);
	}

	static sk_sp<SkShader> Make2Conical(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
	SkPoint center0, center1;
	center0.set(SkScalarAve(pts[0].fX, pts[1].fX),
	SkScalarAve(pts[0].fY, pts[1].fY));
	center1.set(SkScalarInterp(pts[0].fX, pts[1].fX, SkIntToScalar(3)/5),
	SkScalarInterp(pts[0].fY, pts[1].fY, SkIntToScalar(1)/4));
	return SkGradientShader::MakeTwoPointConical(center1, (pts[1].fX - pts[0].fX) / 7,
	center0, (pts[1].fX - pts[0].fX) / 2,
	data.fColors, data.fPos, data.fCount, tm);
	}

	typedef sk_sp<SkShader> (*GradMaker)(const SkPoint pts[2], const GradData&, SkShader::TileMode);
	static const GradMaker gGradMakers[] = {
	MakeLinear, MakeRadial, MakeSweep, Make2Conical
	};

	static void gradient_slide(SkCanvas* canvas) {
	SkPoint pts[2] = {
	{ 0, 0 },
	{ SkIntToScalar(100), SkIntToScalar(100) }
	};
	SkShader::TileMode tm = SkShader::kClamp_TileMode;
	SkRect r = { 0, 0, SkIntToScalar(100), SkIntToScalar(100) };
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setDither(true);

	canvas->translate(SkIntToScalar(20), SkIntToScalar(10));
	for (size_t i = 0; i < SK_ARRAY_COUNT(gGradData); i++) {
	canvas->save();
	for (size_t j = 0; j < SK_ARRAY_COUNT(gGradMakers); j++) {
	paint.setShader(gGradMakers[j](pts, gGradData[i], tm));
	canvas->drawRect(r, paint);
	canvas->translate(0, SkIntToScalar(120));
	}
	canvas->restore();
	canvas->translate(SkIntToScalar(120), 0);
	}
	}

	///////////////////////////////////////////////////////////////////////////////

	#include "SkPathMeasure.h"

	static SkScalar getpathlen(const SkPath& path) {
	SkPathMeasure meas(path, false);
	return meas.getLength();
	}

	static void textonpath_slide(SkCanvas* canvas) {
	const char* text = "Displacement";
	size_t len =strlen(text);
	SkPath path;
	path.moveTo(100, 300);
	path.quadTo(300, 100, 500, 300);
	path.offset(0, -100);

	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setTextSize(40);

	paint.setStyle(SkPaint::kStroke_Style);
	canvas->drawPath(path, paint);
	paint.setStyle(SkPaint::kFill_Style);

	SkScalar x = 50;
	paint.setColor(0xFF008800);
	canvas->drawTextOnPathHV(text, len, path,
	x, paint.getTextSize()*2/3, paint);
	paint.setColor(SK_ColorRED);
	canvas->drawTextOnPathHV(text, len, path,
	x + 60, 0, paint);
	paint.setColor(SK_ColorBLUE);
	canvas->drawTextOnPathHV(text, len, path,
	x + 120, -paint.getTextSize()*2/3, paint);

	path.offset(0, 200);
	paint.setTextAlign(SkPaint::kRight_Align);

	text = "Matrices";
	len = strlen(text);
	SkScalar pathLen = getpathlen(path);
	SkMatrix matrix;

	paint.setColor(SK_ColorBLACK);
	paint.setStyle(SkPaint::kStroke_Style);
	canvas->drawPath(path, paint);
	paint.setStyle(SkPaint::kFill_Style);

	paint.setTextSize(50);
	canvas->drawTextOnPath(text, len, path, nullptr, paint);

	paint.setColor(SK_ColorRED);
	matrix.setScale(-SK_Scalar1, SK_Scalar1);
	matrix.postTranslate(pathLen, 0);
	canvas->drawTextOnPath(text, len, path, &matrix, paint);

	paint.setColor(SK_ColorBLUE);
	matrix.setScale(SK_Scalar1, -SK_Scalar1);
	canvas->drawTextOnPath(text, len, path, &matrix, paint);

	paint.setColor(0xFF008800);
	matrix.setScale(-SK_Scalar1, -SK_Scalar1);
	matrix.postTranslate(pathLen, 0);
	canvas->drawTextOnPath(text, len, path, &matrix, paint);
	}

	///////////////////////////////////////////////////////////////////////////////

	#include "DecodeFile.h"
	#include "SkOSFile.h"
	#include "SkRandom.h"
	#include "SkStream.h"

	static sk_sp<SkShader> make_shader0(SkIPoint* size) {
	SkBitmap bm;

	decode_file("/skimages/logo.gif", &bm);
	size->set(bm.width(), bm.height());
	return SkShader::MakeBitmapShader(bm, SkShader::kClamp_TileMode,
	SkShader::kClamp_TileMode);
	}

	static sk_sp<SkShader> make_shader1(const SkIPoint& size) {
	SkPoint pts[] = { { 0, 0 },
	{ SkIntToScalar(size.fX), SkIntToScalar(size.fY) } };
	SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorRED };
	return SkGradientShader::MakeLinear(pts, colors, nullptr,
	SK_ARRAY_COUNT(colors), SkShader::kMirror_TileMode);
	}

	class Rec {
	public:
	SkVertices::VertexMode fMode;
	int fCount;
	SkPoint* fVerts;
	SkPoint* fTexs;

	Rec() : fCount(0), fVerts(nullptr), fTexs(nullptr) {}
	~Rec() { delete[] fVerts; delete[] fTexs; }
	};

	static void make_tris(Rec* rec) {
	int n = 10;
	SkRandom rand;

	rec->fMode = SkVertices::kTriangles_VertexMode;
	rec->fCount = n * 3;
	rec->fVerts = new SkPoint[rec->fCount];

	for (int i = 0; i < n; i++) {
	SkPoint* v = &rec->fVerts[i*3];
	for (int j = 0; j < 3; j++) {
	v[j].set(rand.nextUScalar1() * 250, rand.nextUScalar1() * 250);
	}
	}
	}

	static void make_fan(Rec* rec, int texWidth, int texHeight) {
	const SkScalar tx = SkIntToScalar(texWidth);
	const SkScalar ty = SkIntToScalar(texHeight);
	const int n = 24;

	rec->fMode = SkVertices::kTriangleFan_VertexMode;
	rec->fCount = n + 2;
	rec->fVerts = new SkPoint[rec->fCount];
	rec->fTexs = new SkPoint[rec->fCount];

	SkPoint* v = rec->fVerts;
	SkPoint* t = rec->fTexs;

	v[0].set(0, 0);
	t[0].set(0, 0);
	for (int i = 0; i < n; i++) {
	SkScalar cos;
	SkScalar sin = SkScalarSinCos(SK_ScalarPI * 2 * i / n, &cos);
	v[i+1].set(cos, sin);
	t[i+1].set(i*tx/n, ty);
	}
	v[n+1] = v[1];
	t[n+1].set(tx, ty);

	SkMatrix m;
	m.setScale(SkIntToScalar(100), SkIntToScalar(100));
	m.postTranslate(SkIntToScalar(110), SkIntToScalar(110));
	m.mapPoints(v, rec->fCount);
	}

	static void make_strip(Rec* rec, int texWidth, int texHeight) {
	const SkScalar tx = SkIntToScalar(texWidth);
	const SkScalar ty = SkIntToScalar(texHeight);
	const int n = 24;

	rec->fMode = SkVertices::kTriangleStrip_VertexMode;
	rec->fCount = 2 * (n + 1);
	rec->fVerts = new SkPoint[rec->fCount];
	rec->fTexs = new SkPoint[rec->fCount];

	SkPoint* v = rec->fVerts;
	SkPoint* t = rec->fTexs;

	for (int i = 0; i < n; i++) {
	SkScalar cos;
	SkScalar sin = SkScalarSinCos(SK_ScalarPI * 2 * i / n, &cos);
	v[i*2 + 0].set(cos/2, sin/2);
	v[i*2 + 1].set(cos, sin);

	t[i2 + 0].set(tx i / n, ty);
	t[i2 + 1].set(tx i / n, 0);
	}
	v[2*n + 0] = v[0];
	v[2*n + 1] = v[1];

	t[2*n + 0].set(tx, ty);
	t[2*n + 1].set(tx, 0);

	SkMatrix m;
	m.setScale(SkIntToScalar(100), SkIntToScalar(100));
	m.postTranslate(SkIntToScalar(110), SkIntToScalar(110));
	m.mapPoints(v, rec->fCount);
	}

	static void mesh_slide(SkCanvas* canvas) {
	Rec fRecs[3];
	SkIPoint size;

	auto fShader0 = make_shader0(&size);
	auto fShader1 = make_shader1(size);

	make_strip(&fRecs[0], size.fX, size.fY);
	make_fan(&fRecs[1], size.fX, size.fY);
	make_tris(&fRecs[2]);

	SkPaint paint;
	paint.setDither(true);
	paint.setFilterQuality(kLow_SkFilterQuality);

	for (size_t i = 0; i < SK_ARRAY_COUNT(fRecs); i++) {
	auto verts = SkVertices::MakeCopy(fRecs[i].fMode, fRecs[i].fCount,
	fRecs[i].fVerts, fRecs[i].fTexs, nullptr);
	canvas->save();

	paint.setShader(nullptr);
	canvas->drawVertices(verts, SkBlendMode::kModulate, paint);

	canvas->translate(SkIntToScalar(210), 0);

	paint.setShader(fShader0);
	canvas->drawVertices(verts, SkBlendMode::kModulate, paint);

	canvas->translate(SkIntToScalar(210), 0);

	paint.setShader(fShader1);
	canvas->drawVertices(verts, SkBlendMode::kModulate, paint);
	canvas->restore();

	canvas->translate(0, SkIntToScalar(250));
	}
	}

	///////////////////////////////////////////////////////////////////////////////

	#include "SkTypeface.h"

	///////////////////////////////////////////////////////////////////////////////

	#include "SkImageEncoder.h"

	static const SlideProc gProc[] = {
	patheffect_slide,
	gradient_slide,
	textonpath_slide,
	mesh_slide,
	};

	class SlideView : public Sample {
	int fIndex;
	bool fOnce;
	public:
	SlideView() {
	fOnce = false;
	}

	void init() {
	if (fOnce) {
	return;
	}
	fOnce = true;

	fIndex = 0;

	SkBitmap bm;
	bm.allocN32Pixels(1024, 768);
	SkCanvas canvas(bm);
	SkScalar s = SkIntToScalar(1024) / 640;
	canvas.scale(s, s);
	for (size_t i = 0; i < SK_ARRAY_COUNT(gProc); i++) {
	canvas.save();
	canvas.drawColor(BG_COLOR);
	gProc[i](&canvas);
	canvas.restore();
	SkString str;
	str.printf("/skimages/slide_" SK_SIZE_T_SPECIFIER ".png", i);
	sk_tool_utils::EncodeImageToFile(str.c_str(), bm, SkEncodedImageFormat::kPNG, 100);
	}
	this->setBGColor(BG_COLOR);
	}

	protected:
	bool onQuery(Sample::Event* evt) override {
	if (Sample::TitleQ(*evt)) {
	Sample::TitleR(evt, "Slides");
	return true;
	}
	return this->INHERITED::onQuery(evt);
	}

	void onDrawContent(SkCanvas* canvas) override {
	this->init();
	gProc[fIndex](canvas);
	}

	Sample::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned) override {
	this->init();
	fIndex = (fIndex + 1) % SK_ARRAY_COUNT(gProc);
	return nullptr;
	}

	private:
	typedef Sample INHERITED;
	};

	//////////////////////////////////////////////////////////////////////////////

	DEF_SAMPLE( return new SlideView(); )