samplecode/SampleGradients.cpp

   1 /*
   2  * Copyright 2011 Google Inc.
   3  *
   4  * Use of this source code is governed by a BSD-style license that can be
   5  * found in the LICENSE file.
   6  */
   7 #include "SampleCode.h"
   8 #include "SkView.h"
   9 #include "SkCanvas.h"
  10 #include "SkGradientShader.h"
  11
  12 static sk_sp<SkShader> setgrad(const SkRect& r, SkColor c0, SkColor c1) {
  13     SkColor colors[] = { c0, c1 };
  14     SkPoint pts[] = { { r.fLeft, r.fTop }, { r.fRight, r.fTop } };
  15     return SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kClamp_TileMode);
  16 }
  17
  18 static void test_alphagradients(SkCanvas* canvas) {
  19     SkRect r;
  20     r.set(SkIntToScalar(10), SkIntToScalar(10),
  21           SkIntToScalar(410), SkIntToScalar(30));
  22     SkPaint p, p2;
  23     p2.setStyle(SkPaint::kStroke_Style);
  24
  25     p.setShader(setgrad(r, 0xFF00FF00, 0x0000FF00));
  26     canvas->drawRect(r, p);
  27     canvas->drawRect(r, p2);
  28
  29     r.offset(0, r.height() + SkIntToScalar(4));
  30     p.setShader(setgrad(r, 0xFF00FF00, 0x00000000));
  31     canvas->drawRect(r, p);
  32     canvas->drawRect(r, p2);
  33
  34     r.offset(0, r.height() + SkIntToScalar(4));
  35     p.setShader(setgrad(r, 0xFF00FF00, 0x00FF0000));
  36     canvas->drawRect(r, p);
  37     canvas->drawRect(r, p2);
  38 }
  39
  40 ///////////////////////////////////////////////////////////////////////////////
  41
  42 struct GradData {
  43     int             fCount;
  44     const SkColor*  fColors;
  45     const SkScalar* fPos;
  46 };
  47
  48 static const SkColor gColors[] = {
  49     SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorWHITE, SK_ColorBLACK
  50 };
  51 static const SkScalar gPos0[] = { 0, SK_Scalar1 };
  52 static const SkScalar gPos1[] = { SK_Scalar1/4, SK_Scalar1*3/4 };
  53 static const SkScalar gPos2[] = {
  54     0, SK_Scalar1/8, SK_Scalar1/2, SK_Scalar1*7/8, SK_Scalar1
  55 };
  56
  57 static const GradData gGradData[] = {
  58     { 2, gColors, nullptr },
  59     { 2, gColors, gPos0 },
  60     { 2, gColors, gPos1 },
  61     { 5, gColors, nullptr },
  62     { 5, gColors, gPos2 }
  63 };
  64
  65 static sk_sp<SkShader> MakeLinear(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
  66     return SkGradientShader::MakeLinear(pts, data.fColors, data.fPos, data.fCount, tm);
  67 }
  68
  69 static sk_sp<SkShader> MakeRadial(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
  70     SkPoint center;
  71     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
  72                SkScalarAve(pts[0].fY, pts[1].fY));
  73     return SkGradientShader::MakeRadial(center, center.fX, data.fColors,
  74                                         data.fPos, data.fCount, tm);
  75 }
  76
  77 static sk_sp<SkShader> MakeSweep(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
  78     SkPoint center;
  79     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
  80                SkScalarAve(pts[0].fY, pts[1].fY));
  81     return SkGradientShader::MakeSweep(center.fX, center.fY, data.fColors, data.fPos, data.fCount);
  82 }
  83
  84 static sk_sp<SkShader> Make2Conical(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm) {
  85     SkPoint center0, center1;
  86     center0.set(SkScalarAve(pts[0].fX, pts[1].fX),
  87                 SkScalarAve(pts[0].fY, pts[1].fY));
  88     center1.set(SkScalarInterp(pts[0].fX, pts[1].fX, SkIntToScalar(3)/5),
  89                 SkScalarInterp(pts[0].fY, pts[1].fY, SkIntToScalar(1)/4));
  90     return SkGradientShader::MakeTwoPointConical(
  91                             center1, (pts[1].fX - pts[0].fX) / 7,
  92                             center0, (pts[1].fX - pts[0].fX) / 2,
  93                             data.fColors, data.fPos, data.fCount, tm);
  94 }
  95
  96 static sk_sp<SkShader> Make2ConicalConcentric(const SkPoint pts[2], const GradData& data,
  97                                        SkShader::TileMode tm) {
  98     SkPoint center;
  99     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
 100                SkScalarAve(pts[0].fY, pts[1].fY));
 101     return SkGradientShader::MakeTwoPointConical(
 102                             center, (pts[1].fX - pts[0].fX) / 7,
 103                             center, (pts[1].fX - pts[0].fX) / 2,
 104                             data.fColors, data.fPos, data.fCount, tm);
 105 }
 106
 107 typedef sk_sp<SkShader> (*GradMaker)(const SkPoint pts[2], const GradData& data, SkShader::TileMode tm);
 108
 109 static const GradMaker gGradMakers[] = {
 110     MakeLinear, MakeRadial, MakeSweep, Make2Conical, Make2ConicalConcentric
 111 };
 112
 113 ///////////////////////////////////////////////////////////////////////////////
 114
 115 class GradientsView : public SampleView {
 116 public:
 117     GradientsView() {
 118         this->setBGColor(0xFFDDDDDD);
 119     }
 120
 121 protected:
 122     bool onQuery(SkEvent* evt) override {
 123         if (SampleCode::TitleQ(*evt)) {
 124             SampleCode::TitleR(evt, "Gradients");
 125             return true;
 126         }
 127         return this->INHERITED::onQuery(evt);
 128     }
 129
 130     void onDrawContent(SkCanvas* canvas) override {
 131         SkPoint pts[2] = {
 132             { 0, 0 },
 133             { SkIntToScalar(100), SkIntToScalar(100) }
 134         };
 135         SkRect r = { 0, 0, SkIntToScalar(100), SkIntToScalar(100) };
 136         SkPaint paint;
 137         paint.setDither(true);
 138
 139         canvas->save();
 140         canvas->translate(SkIntToScalar(20), SkIntToScalar(10));
 141
 142         for (int tm = 0; tm < SkShader::kTileModeCount; ++tm) {
 143             canvas->save();
 144             for (size_t i = 0; i < SK_ARRAY_COUNT(gGradData); i++) {
 145                 canvas->save();
 146                 for (size_t j = 0; j < SK_ARRAY_COUNT(gGradMakers); j++) {
 147                     paint.setShader(gGradMakers[j](pts, gGradData[i], (SkShader::TileMode)tm));
 148                     canvas->drawRect(r, paint);
 149                     canvas->translate(0, SkIntToScalar(120));
 150                 }
 151                 canvas->restore();
 152                 canvas->translate(SkIntToScalar(120), 0);
 153             }
 154             canvas->restore();
 155             canvas->translate(SK_ARRAY_COUNT(gGradData)*SkIntToScalar(120), 0);
 156         }
 157         canvas->restore();
 158
 159         canvas->translate(0, SkIntToScalar(370));
 160         if (false) { // avoid bit rot, suppress warning
 161             test_alphagradients(canvas);
 162         }
 163         this->inval(nullptr);
 164     }
 165
 166 private:
 167     typedef SampleView INHERITED;
 168 };
 169
 170 ///////////////////////////////////////////////////////////////////////////////
 171
 172 static SkView* MyFactory() { return new GradientsView; }
 173 static SkViewRegister reg(MyFactory);