gradients.cpp File Reference

#include "gm/gm.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorSpace.h"
#include "include/core/SkFont.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPicture.h"
#include "include/core/SkPictureRecorder.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkGradientShader.h"
#include "include/private/base/SkAssert.h"
#include "tools/ToolUtils.h"
#include "tools/fonts/FontToolUtils.h"
#include <initializer_list>
#include <math.h>

Go to the source code of this file.

Classes
struct	GradRun

Macros
#define	SIZE   121
#define	DEF_POWERLESS_HUE_GM(colorSpace)

Functions
static sk_sp< SkShader >	make_linear (const GradRun &run, SkTileMode mode)
static sk_sp< SkShader >	make_radial (const GradRun &run, SkTileMode mode)
static sk_sp< SkShader >	make_conical (const GradRun &run, SkTileMode mode)
static sk_sp< SkShader >	make_sweep (const GradRun &run, SkTileMode)
	DEF_SIMPLE_GM (gradients_dup_color_stops, canvas, 704, 564)
static void	draw_many_stops (SkCanvas *canvas)
	DEF_SIMPLE_GM (gradient_many_stops, canvas, 500, 500)
static void	draw_many_hard_stops (SkCanvas *canvas)
	DEF_SIMPLE_GM (gradient_many_hard_stops, canvas, 500, 500)
static void	draw_circle_shader (SkCanvas *canvas, SkScalar cx, SkScalar cy, SkScalar r, sk_sp< SkShader >(*shaderFunc)())
	DEF_SIMPLE_GM (fancy_gradients, canvas, 800, 300)
	DEF_SIMPLE_GM (sweep_tiling, canvas, 690, 512)
	DEF_SIMPLE_GM (rgbw_sweep_gradient, canvas, 100, 100)
	DEF_SIMPLE_GM (gradients_interesting, canvas, 640, 1300)
	DEF_SIMPLE_GM_BG (gradients_color_space, canvas, 265, 255, SK_ColorGRAY)
	DEF_SIMPLE_GM_BG (gradients_hue_method, canvas, 285, 155, SK_ColorGRAY)
	DEF_SIMPLE_GM_BG (gradients_color_space_tilemode, canvas, 360, 105, SK_ColorGRAY)
	DEF_SIMPLE_GM_BG (gradients_color_space_many_stops, canvas, 500, 500, SK_ColorGRAY)
static void	draw_powerless_hue_gradients (SkCanvas *canvas, SkGradientShader::Interpolation::ColorSpace colorSpace)

Macro Definition Documentation

DEF_POWERLESS_HUE_GM

#define DEF_POWERLESS_HUE_GM

(

colorSpace

)

Value:

    DEF_SIMPLE_GM(gradients_powerless_hue_##colorSpace, canvas, 415, 330) {                       \
        draw_powerless_hue_gradients(canvas,                                                      \
                                     SkGradientShader::Interpolation::ColorSpace::k##colorSpace); \
    }

Definition at line 1394 of file gradients.cpp.

                                                                          {                       \
        draw_powerless_hue_gradients(canvas,                                                      \
                                     SkGradientShader::Interpolation::ColorSpace::k##colorSpace); \
    }

SIZE

#define SIZE   121

Definition at line 776 of file gradients.cpp.

Function Documentation

DEF_SIMPLE_GM() [1/7]

DEF_SIMPLE_GM	(	fancy_gradients	,
		canvas	,
		800	,
		300
	)

Definition at line 927 of file gradients.cpp.

                                                 {
    draw_circle_shader(canvas, 150, 150, 100, []() -> sk_sp<SkShader> {
        // Checkerboard using two linear gradients + picture shader.
        SkScalar kTileSize = 80 / sqrtf(2);
        SkColor colors1[] = { 0xff000000, 0xff000000,
                              0xffffffff, 0xffffffff,
                              0xff000000, 0xff000000 };
        SkColor colors2[] = { 0xff000000, 0xff000000,
                              0x00000000, 0x00000000,
                              0xff000000, 0xff000000 };
        SkScalar pos[] = { 0, .25f, .25f, .75f, .75f, 1 };
        static_assert(std::size(colors1) == std::size(pos), "color/pos size mismatch");
        static_assert(std::size(colors2) == std::size(pos), "color/pos size mismatch");
 
        SkPictureRecorder recorder;
        recorder.beginRecording(SkRect::MakeWH(kTileSize, kTileSize));
 
        SkPaint p;
 
        SkPoint pts1[] = { { 0, 0 }, { kTileSize, kTileSize }};
        p.setShader(SkGradientShader::MakeLinear(pts1, colors1, pos, std::size(colors1),
                                                 SkTileMode::kClamp, 0, nullptr));
        recorder.getRecordingCanvas()->drawPaint(p);
 
        SkPoint pts2[] = { { 0, kTileSize }, { kTileSize, 0 }};
        p.setShader(SkGradientShader::MakeLinear(pts2, colors2, pos, std::size(colors2),
                                                 SkTileMode::kClamp, 0, nullptr));
        recorder.getRecordingCanvas()->drawPaint(p);
 
        SkMatrix m = SkMatrix::I();
        m.preRotate(45);
        return recorder.finishRecordingAsPicture()->makeShader(
                                           SkTileMode::kRepeat, SkTileMode::kRepeat,
                                           SkFilterMode::kNearest, &m, nullptr);
    });
 
    draw_circle_shader(canvas, 400, 150, 100, []() -> sk_sp<SkShader> {
        // Checkerboard using a sweep gradient + picture shader.
        SkScalar kTileSize = 80;
        SkColor colors[] = { 0xff000000, 0xff000000,
                             0xffffffff, 0xffffffff,
                             0xff000000, 0xff000000,
                             0xffffffff, 0xffffffff };
        SkScalar pos[] = { 0, .25f, .25f, .5f, .5f, .75f, .75f, 1 };
        static_assert(std::size(colors) == std::size(pos), "color/pos size mismatch");
 
        SkPaint p;
        p.setShader(SkGradientShader::MakeSweep(kTileSize / 2, kTileSize / 2,
                                                colors, pos, std::size(colors), 0, nullptr));
        SkPictureRecorder recorder;
        recorder.beginRecording(SkRect::MakeWH(kTileSize, kTileSize))->drawPaint(p);
 
        return recorder.finishRecordingAsPicture()->makeShader(
                                           SkTileMode::kRepeat,
                                           SkTileMode::kRepeat, SkFilterMode::kNearest);
    });
 
    draw_circle_shader(canvas, 650, 150, 100, []() -> sk_sp<SkShader> {
        // Dartboard using sweep + radial.
        const SkColor a = 0xffffffff;
        const SkColor b = 0xff000000;
        SkColor colors[] = { a, a, b, b, a, a, b, b, a, a, b, b, a, a, b, b};
        SkScalar pos[] = { 0, .125f, .125f, .25f, .25f, .375f, .375f, .5f, .5f,
                           .625f, .625f, .75f, .75f, .875f, .875f, 1};
        static_assert(std::size(colors) == std::size(pos), "color/pos size mismatch");
 
        SkPoint center = { 650, 150 };
        sk_sp<SkShader> sweep1 = SkGradientShader::MakeSweep(center.x(), center.y(), colors, pos,
                                                             std::size(colors), 0, nullptr);
        SkMatrix m = SkMatrix::I();
        m.preRotate(22.5f, center.x(), center.y());
        sk_sp<SkShader> sweep2 = SkGradientShader::MakeSweep(center.x(), center.y(), colors, pos,
                                                             std::size(colors), 0, &m);
 
        sk_sp<SkShader> sweep(SkShaders::Blend(SkBlendMode::kExclusion, sweep1, sweep2));
 
        SkScalar radialPos[] = { 0, .02f, .02f, .04f, .04f, .08f, .08f, .16f, .16f, .31f, .31f,
                                 .62f, .62f, 1, 1, 1 };
        static_assert(std::size(colors) == std::size(radialPos),
                      "color/pos size mismatch");
 
        return SkShaders::Blend(SkBlendMode::kExclusion, sweep,
                                SkGradientShader::MakeRadial(center, 100, colors,
                                                             radialPos,
                                                             std::size(radialPos),
                                                             SkTileMode::kClamp));
    });
}

DEF_SIMPLE_GM() [2/7]

DEF_SIMPLE_GM	(	gradient_many_hard_stops	,
		canvas	,
		500	,
		500
	)

Definition at line 909 of file gradients.cpp.

                                                          {
    draw_many_hard_stops(canvas);
}

DEF_SIMPLE_GM() [3/7]

DEF_SIMPLE_GM	(	gradient_many_stops	,
		canvas	,
		500	,
		500
	)

Definition at line 880 of file gradients.cpp.

                                                     {
    draw_many_stops(canvas);
}

DEF_SIMPLE_GM() [4/7]

DEF_SIMPLE_GM	(	gradients_dup_color_stops	,
		canvas	,
		704	,
		564
	)

Definition at line 807 of file gradients.cpp.

                                                           {
    const SkColor preColor  = 0xFFFF0000;   // clamp color before start
    const SkColor postColor = 0xFF0000FF;   // clamp color after end
    const SkColor color0    = 0xFF000000;
    const SkColor color1    = 0xFF00FF00;
    const SkColor badColor  = 0xFF3388BB;   // should never be seen, fills out fixed-size array
 
    const GradRun runs[] = {
        {   { color0, color1, badColor, badColor },
            { 0, 1, -1, -1 },
            2,
        },
        {   { preColor, color0, color1, badColor },
            { 0, 0, 1, -1 },
            3,
        },
        {   { color0, color1, postColor, badColor },
            { 0, 1, 1, -1 },
            3,
        },
        {   { preColor, color0, color1, postColor },
            { 0, 0, 1, 1 },
            4,
        },
        {   { color0, color0, color1, color1 },
            { 0, 0.5f, 0.5f, 1 },
            4,
        },
    };
    sk_sp<SkShader> (*factories[])(const GradRun&, SkTileMode) {
        make_linear, make_radial, make_conical, make_sweep
    };
 
    const SkRect rect = SkRect::MakeWH(SIZE, SIZE);
    const SkScalar dx = SIZE + 20;
    const SkScalar dy = SIZE + 20;
    const SkTileMode mode = SkTileMode::kClamp;
 
    SkPaint paint;
    canvas->translate(10, 10 - dy);
    for (auto factory : factories) {
        canvas->translate(0, dy);
        SkAutoCanvasRestore acr(canvas, true);
        for (const auto& run : runs) {
            paint.setShader(factory(run, mode));
            canvas->drawRect(rect, paint);
            canvas->translate(dx, 0);
        }
    }
}

DEF_SIMPLE_GM() [5/7]

DEF_SIMPLE_GM	(	gradients_interesting	,
		canvas	,
		640	,
		1300
	)

Definition at line 1070 of file gradients.cpp.

                                                        {
    static const SkColor colors2[] = { SK_ColorRED, SK_ColorBLUE };
    static const SkColor colors3[] = { SK_ColorRED, SK_ColorYELLOW, SK_ColorBLUE };
    static const SkColor colors4[] = { SK_ColorRED, SK_ColorYELLOW, SK_ColorYELLOW, SK_ColorBLUE };
 
    static const SkScalar softRight[]  = { 0, .999f,   1 }; // Based on Android launcher "clipping"
    static const SkScalar hardLeft[]   = { 0,     0,   1 };
    static const SkScalar hardRight[]  = { 0,     1,   1 };
    static const SkScalar hardCenter[] = { 0,   .5f, .5f, 1 };
 
    static const struct {
        const SkColor*  colors;
        const SkScalar* pos;
        int             count;
    } configs[] = {
        { colors2,    nullptr, 2 }, // kTwo_ColorType
        { colors3,    nullptr, 3 }, // kThree_ColorType (simple)
        { colors3,  softRight, 3 }, // kThree_ColorType (tricky)
        { colors3,   hardLeft, 3 }, // kHardStopLeftEdged_ColorType
        { colors3,  hardRight, 3 }, // kHardStopRightEdged_ColorType
        { colors4, hardCenter, 4 }, // kSingleHardStop_ColorType
    };
 
    static const SkTileMode modes[] = {
        SkTileMode::kClamp,
        SkTileMode::kRepeat,
        SkTileMode::kMirror,
    };
 
    static constexpr SkScalar size = 200;
    static const SkPoint pts[] = { { size / 3, size / 3 }, { size * 2 / 3, size * 2 / 3} };
 
    SkPaint p;
    for (const auto& cfg : configs) {
        {
            SkAutoCanvasRestore acr(canvas, true);
            for (auto mode : modes) {
                p.setShader(SkGradientShader::MakeLinear(pts, cfg.colors, cfg.pos, cfg.count,
                                                         mode));
                canvas->drawRect(SkRect::MakeWH(size, size), p);
                canvas->translate(size * 1.1f, 0);
            }
        }
        canvas->translate(0, size * 1.1f);
    }
}

DEF_SIMPLE_GM() [6/7]

DEF_SIMPLE_GM	(	rgbw_sweep_gradient	,
		canvas	,
		100	,
		100
	)

Definition at line 1055 of file gradients.cpp.

                                                     {
    static constexpr SkScalar size = 100;
    static constexpr SkColor colors[] = {SK_ColorWHITE, SK_ColorWHITE,
                                         SK_ColorBLUE, SK_ColorBLUE,
                                         SK_ColorRED, SK_ColorRED,
                                         SK_ColorGREEN, SK_ColorGREEN};
    static constexpr SkScalar   pos[] = { 0, .25f, .25f, .50f, .50f, .75, .75, 1 };
    static_assert(std::size(colors) == std::size(pos), "size mismatch");
 
    SkPaint p;
    p.setShader(SkGradientShader::MakeSweep(size / 2, size / 2, colors, pos, std::size(colors)));
    canvas->drawRect(SkRect::MakeWH(size, size), p);
}

DEF_SIMPLE_GM() [7/7]

DEF_SIMPLE_GM	(	sweep_tiling	,
		canvas	,
		690	,
		512
	)

Definition at line 1016 of file gradients.cpp.

                                              {
    static constexpr SkScalar size = 160;
    static constexpr SkColor colors[] = { SK_ColorBLUE, SK_ColorYELLOW, SK_ColorGREEN };
    static constexpr SkScalar   pos[] = { 0, .25f, .50f };
    static_assert(std::size(colors) == std::size(pos), "size mismatch");
 
    static constexpr SkTileMode modes[] = { SkTileMode::kClamp,
                                            SkTileMode::kRepeat,
                                            SkTileMode::kMirror };
 
    static const struct {
        SkScalar start, end;
    } angles[] = {
        { -330, -270 },
        {   30,   90 },
        {  390,  450 },
        {  -30,  800 },
    };
 
    SkPaint p;
    const SkRect r = SkRect::MakeWH(size, size);
 
    for (auto mode : modes) {
        {
            SkAutoCanvasRestore acr(canvas, true);
 
            for (auto angle : angles) {
                p.setShader(SkGradientShader::MakeSweep(size / 2, size / 2, colors, pos,
                                                        std::size(colors), mode,
                                                        angle.start, angle.end, 0, nullptr));
 
                canvas->drawRect(r, p);
                canvas->translate(size * 1.1f, 0);
            }
        }
        canvas->translate(0, size * 1.1f);
    }
}

DEF_SIMPLE_GM_BG() [1/4]

DEF_SIMPLE_GM_BG	(	gradients_color_space	,
		canvas	,
		265	,
		255	,
		SK_ColorGRAY
	)

Definition at line 1118 of file gradients.cpp.

                                                                        {
    using CS = SkGradientShader::Interpolation::ColorSpace;
 
    struct Config {
        CS fColorSpace;
        const char* fLabel;
    };
    static const Config kConfigs[] = {
        { CS::kSRGB,          "sRGB" },
        { CS::kSRGBLinear,    "Linear" },
        { CS::kLab,           "Lab" },
        { CS::kOKLab,         "OKLab" },
        { CS::kOKLabGamutMap, "OKLabGamutMap" },
        { CS::kLCH,           "LCH" },
        { CS::kOKLCH,         "OKLCH" },
        { CS::kOKLCHGamutMap, "OKLCHGamutMap" },
        { CS::kHSL,           "HSL" },
        { CS::kHWB,           "HWB" },
    };
 
    SkPoint pts[] = {{0, 0}, {200, 0}};
    SkColor4f colors[] = {SkColors::kBlue, SkColors::kYellow};
 
    SkPaint labelPaint;
    SkPaint p;
    SkGradientShader::Interpolation interpolation;
    canvas->translate(5, 5);
    SkFont font = ToolUtils::DefaultPortableFont();
 
    for (const Config& config : kConfigs) {
        interpolation.fColorSpace = config.fColorSpace;
        p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), nullptr, 2,
                                                 SkTileMode::kClamp, interpolation, nullptr));
        canvas->drawRect({0, 0, 200, 20}, p);
        canvas->drawSimpleText(config.fLabel, strlen(config.fLabel), SkTextEncoding::kUTF8, 210, 15,
                               font, labelPaint);
        canvas->translate(0, 25);
    }
}

DEF_SIMPLE_GM_BG() [2/4]

DEF_SIMPLE_GM_BG	(	gradients_color_space_many_stops	,
		canvas	,
		500	,
		500	,
		SK_ColorGRAY
	)

Definition at line 1240 of file gradients.cpp.

                                                                                   {
    // Test exotic (CSS) gradient color spaces with many stops. Rather than test every combination,
    // we pick one color space that has a sufficiently strange interpolated representation (OKLCH)
    // and just use that. We're mostly interested in making sure that the texture fallback on GPU
    // works correctly.
    const SkPoint pts[] = { {50, 50}, {450, 465}};
 
    const unsigned kStopCount = 200;
    SkColor4f colors[kStopCount];
    for (unsigned i = 0; i < kStopCount; i++) {
        switch (i % 5) {
            case 0: colors[i] = SkColors::kRed; break;
            case 1: colors[i] = SkColors::kGreen; break;
            case 2: colors[i] = SkColors::kGreen; break;
            case 3: colors[i] = SkColors::kBlue; break;
            case 4: colors[i] = SkColors::kRed; break;
        }
    }
 
    SkPaint p;
 
    SkGradientShader::Interpolation interpolation;
    interpolation.fColorSpace = SkGradientShader::Interpolation::ColorSpace::kOKLCH;
    p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), nullptr,
                                             std::size(colors), SkTileMode::kClamp, interpolation,
                                             nullptr));
 
    canvas->drawRect(SkRect::MakeXYWH(0, 0, 500, 500), p);
}

DEF_SIMPLE_GM_BG() [3/4]

DEF_SIMPLE_GM_BG	(	gradients_color_space_tilemode	,
		canvas	,
		360	,
		105	,
		SK_ColorGRAY
	)

Definition at line 1216 of file gradients.cpp.

                                                                                 {
    // Test exotic (CSS) gradient color spaces in conjunction with tile modes. Rather than test
    // every combination, we pick one color space that has a sufficiently strange interpolated
    // representation (OKLCH) and just use that. We're mostly interested in making sure that things
    // like decal mode are implemented at the correct time in the pipeline, relative to hue
    // conversion, re-premultiplication, etc.
    SkPoint pts[] = {{20, 0}, {120, 0}};
    SkColor4f colors[] = {SkColors::kBlue, SkColors::kYellow};
 
    SkPaint p;
    SkGradientShader::Interpolation interpolation;
    interpolation.fColorSpace = SkGradientShader::Interpolation::ColorSpace::kOKLCH;
 
    canvas->translate(5, 5);
 
    for (int tm = 0; tm < kSkTileModeCount; ++tm) {
        p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), nullptr, 2,
                                                 static_cast<SkTileMode>(tm), interpolation,
                                                 nullptr));
        canvas->drawRect({0, 0, 350, 20}, p);
        canvas->translate(0, 25);
    }
}

DEF_SIMPLE_GM_BG() [4/4]

DEF_SIMPLE_GM_BG	(	gradients_hue_method	,
		canvas	,
		285	,
		155	,
		SK_ColorGRAY
	)

Definition at line 1158 of file gradients.cpp.

                                                                       {
    using HM = SkGradientShader::Interpolation::HueMethod;
 
    struct Config {
        HM fHueMethod;
        const char* fLabel;
    };
    static const Config kConfigs[] = {
        { HM::kShorter,    "Shorter" },
        { HM::kLonger,     "Longer" },
        { HM::kIncreasing, "Increasing" },
        { HM::kDecreasing, "Decreasing" },
    };
 
    SkPoint pts[] = {{0, 0}, {200, 0}};
    SkColor4f colors[] = {SkColors::kRed, SkColors::kGreen, SkColors::kRed, SkColors::kRed };
 
    SkPaint labelPaint;
    SkPaint p;
    SkGradientShader::Interpolation interpolation;
    interpolation.fColorSpace = SkGradientShader::Interpolation::ColorSpace::kHSL;
    canvas->translate(5, 5);
    SkFont font = ToolUtils::DefaultPortableFont();
 
    for (const Config& config : kConfigs) {
        interpolation.fHueMethod = config.fHueMethod;
        p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), nullptr, 4,
                                                 SkTileMode::kClamp, interpolation, nullptr));
        canvas->drawRect({0, 0, 200, 20}, p);
        canvas->drawSimpleText(config.fLabel, strlen(config.fLabel), SkTextEncoding::kUTF8, 210, 15,
                               font, labelPaint);
        canvas->translate(0, 25);
    }
 
    // Test a bug (skia:13941) with how gradient shaders handle explicit positions.
    // If there are no explicit positions at 0 or 1, those are automatically added, with copies of
    // the first/last color. When using kLonger, this can produce extra gradient that should
    // actually be solid. This gradient *should* be:
    //   |- solid red -|- red to green, the long way -|- solid green -|
    interpolation.fHueMethod = HM::kLonger;
    SkScalar middlePos[] = { 0.3f, 0.7f };
    p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), middlePos, 2,
                                             SkTileMode::kClamp, interpolation, nullptr));
    canvas->drawRect({0, 0, 200, 20}, p);
    canvas->translate(0, 25);
 
    // However... if the user explicitly includes those duplicate color stops in kLonger mode,
    // we expect the gradient to do a full rotation in those regions:
    //  |- full circle, red to red -|- red to green -|- full circle, green to green -|
    colors[0] = colors[1] = SkColors::kRed;
    colors[2] = colors[3] = SkColors::kGreen;
    SkScalar allPos[] = { 0.0f, 0.3f, 0.7f, 1.0f };
    p.setShader(SkGradientShader::MakeLinear(pts, colors, SkColorSpace::MakeSRGB(), allPos, 4,
                                             SkTileMode::kClamp, interpolation, nullptr));
    canvas->drawRect({0, 0, 200, 20}, p);
    canvas->translate(0, 25);
}

draw_circle_shader()

static void draw_circle_shader ( SkCanvas *  canvas, SkScalar  cx, SkScalar  cy, SkScalar  r, sk_sp< SkShader >(*)()  shaderFunc  )

static

Definition at line 913 of file gradients.cpp.

                                                                {
    SkPaint p;
    p.setAntiAlias(true);
    p.setShader(shaderFunc());
    canvas->drawCircle(cx, cy, r, p);
 
    p.setShader(nullptr);
    p.setColor(SK_ColorGRAY);
    p.setStyle(SkPaint::kStroke_Style);
    p.setStrokeWidth(2);
    canvas->drawCircle(cx, cy, r, p);
}

draw_many_hard_stops()

static void draw_many_hard_stops ( SkCanvas *  canvas )

static

Definition at line 884 of file gradients.cpp.

                                                   {
    const unsigned kStopCount = 300;
    const SkPoint pts[] = {{50, 50}, {450, 450}};
 
    SkColor colors[kStopCount];
    SkScalar pos[kStopCount];
    for (unsigned i = 0; i < kStopCount; i++) {
        switch (i % 6) {
            case 0: colors[i] = SK_ColorRED;   break;
            case 1: colors[i] = SK_ColorGREEN; break;
            case 2: colors[i] = SK_ColorGREEN; break;
            case 3: colors[i] = SK_ColorBLUE;  break;
            case 4: colors[i] = SK_ColorBLUE;  break;
            case 5: colors[i] = SK_ColorRED;   break;
        }
        pos[i] = (2.0f * (i / 2)) / kStopCount;
    }
 
    SkPaint p;
    p.setShader(SkGradientShader::MakeLinear(pts, colors, pos, std::size(colors),
                                             SkTileMode::kClamp));
 
    canvas->drawRect(SkRect::MakeXYWH(0, 0, 500, 500), p);
}

draw_many_stops()

static void draw_many_stops ( SkCanvas *  canvas )

static

Definition at line 858 of file gradients.cpp.

                                              {
    const unsigned kStopCount = 200;
    const SkPoint pts[] = { {50, 50}, {450, 450}};
 
    SkColor colors[kStopCount];
    for (unsigned i = 0; i < kStopCount; i++) {
        switch (i % 5) {
        case 0: colors[i] = SK_ColorRED;   break;
        case 1: colors[i] = SK_ColorGREEN; break;
        case 2: colors[i] = SK_ColorGREEN; break;
        case 3: colors[i] = SK_ColorBLUE;  break;
        case 4: colors[i] = SK_ColorRED;   break;
        }
    }
 
    SkPaint p;
    p.setShader(SkGradientShader::MakeLinear(pts, colors, nullptr, std::size(colors),
                                             SkTileMode::kClamp));
 
    canvas->drawRect(SkRect::MakeXYWH(0, 0, 500, 500), p);
}

draw_powerless_hue_gradients()

static void draw_powerless_hue_gradients ( SkCanvas *  canvas, SkGradientShader::Interpolation::ColorSpace  colorSpace  )

static

Definition at line 1270 of file gradients.cpp.

                                                                                             {
    ToolUtils::draw_checkerboard(canvas);
 
    auto nextRow = [=]() {
        canvas->restore();
        canvas->translate(0, 25);
        canvas->save();
    };
 
    auto gradient = [&](std::initializer_list<SkColor4f> colors,
                        std::initializer_list<float> pos,
                        bool inPremul = false) {
        using Interpolation = SkGradientShader::Interpolation;
        SkASSERT(pos.size() == 0 || pos.size() == colors.size());
        SkPaint paint;
        SkPoint pts[] = {{0, 0}, {200, 0}};
        Interpolation interpolation;
        interpolation.fColorSpace = colorSpace;
        interpolation.fInPremul = static_cast<Interpolation::InPremul>(inPremul);
        paint.setShader(SkGradientShader::MakeLinear(pts,
                                                     colors.begin(),
                                                     SkColorSpace::MakeSRGB(),
                                                     pos.size() == 0 ? nullptr : pos.begin(),
                                                     colors.size(),
                                                     SkTileMode::kClamp,
                                                     interpolation,
                                                     nullptr));
        canvas->drawRect({0, 0, 200, 20}, paint);
        canvas->translate(205, 0); // next column
    };
 
    canvas->translate(5, 5);
    canvas->save();
 
    // For each test case, the first gradient (first column) has an under-specified result due to a
    // powerless component after conversion to LCH. The second gradient (second column) "hints" the
    // correct result, by slightly tinting the otherwise powerless color.
 
    gradient({SkColors::kWhite,            SkColors::kBlue}, {});
    gradient({{0.99f, 0.99f, 1.00f, 1.0f}, SkColors::kBlue}, {}); // white, with blue hue
    nextRow();
 
    gradient({SkColors::kBlack,            SkColors::kBlue}, {});
    gradient({{0.00f, 0.00f, 0.01f, 1.0f}, SkColors::kBlue}, {}); // black, with blue hue
    nextRow();
 
    // Transparent cases are done in both premul and unpremul interpolation:
 
    gradient({SkColors::kTransparent,      SkColors::kBlue}, {}, /*inPremul=*/false);
    gradient({{0.00f, 0.00f, 0.01f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/false);
    nextRow();
 
    gradient({SkColors::kTransparent,      SkColors::kBlue}, {}, /*inPremul=*/true);
    gradient({{0.00f, 0.00f, 0.01f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/true);
    nextRow();
 
    gradient({{1.00f, 1.00f, 1.00f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/false);
    gradient({{0.99f, 0.99f, 1.00f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/false);
    nextRow();
 
    gradient({{1.00f, 1.00f, 1.00f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/true);
    gradient({{0.99f, 0.99f, 1.00f, 0.0f}, SkColors::kBlue}, {}, /*inPremul=*/true);
    nextRow();
 
    // Now we test three-stop gradients, where the middle stop needs to be "split" to handle the
    // different hues on either side. Again, the second column explicitly injects those to produce
    // a reference result. See: https://github.com/w3c/csswg-drafts/issues/9295
 
    gradient({SkColors::kRed, SkColors::kWhite, SkColors::kBlue}, {});
    gradient({SkColors::kRed,
              {1.00f, 0.99f, 0.99f, 1.0f},
              {0.99f, 0.99f, 1.00f, 1.0f},
              SkColors::kBlue},
             {0.0f, 0.5f, 0.5f, 1.0f});
    nextRow();
 
    gradient({SkColors::kRed, SkColors::kBlack, SkColors::kBlue}, {});
    gradient({SkColors::kRed,
              {0.01f, 0.00f, 0.00f, 1.0f},
              {0.00f, 0.00f, 0.01f, 1.0f},
              SkColors::kBlue},
             {0.0f, 0.5f, 0.5f, 1.0f});
    nextRow();
 
    gradient({SkColors::kRed, SkColors::kTransparent, SkColors::kBlue}, {});
    gradient({SkColors::kRed,
              {0.01f, 0.00f, 0.00f, 0.0f},
              {0.00f, 0.00f, 0.01f, 0.0f},
              SkColors::kBlue},
             {0.0f, 0.5f, 0.5f, 1.0f});
    nextRow();
 
    // Now do a few black-white tests, to ensure that the hue propagation works correctly, even
    // when there isn't any hue in the adjacent stops.
    using HueMethod = SkGradientShader::Interpolation::HueMethod;
    auto blackWhiteGradient = [&](HueMethod hm) {
        using Interpolation = SkGradientShader::Interpolation;
        SkPaint paint;
        SkPoint pts[] = {{0, 0}, {405, 0}};
        Interpolation interpolation;
        interpolation.fColorSpace = colorSpace;
        interpolation.fHueMethod = hm;
        const SkColor4f colors[] = {SkColors::kWhite, SkColors::kGray,
                                    SkColors::kWhite, SkColors::kDkGray,
                                    SkColors::kWhite, SkColors::kBlack};
        paint.setShader(SkGradientShader::MakeLinear(pts,
                                                     colors,
                                                     SkColorSpace::MakeSRGB(),
                                                     nullptr,
                                                     std::size(colors),
                                                     SkTileMode::kClamp,
                                                     interpolation,
                                                     nullptr));
        canvas->drawRect({0, 0, 405, 20}, paint);
        nextRow();
    };
 
    blackWhiteGradient(HueMethod::kShorter);
    blackWhiteGradient(HueMethod::kIncreasing);
    blackWhiteGradient(HueMethod::kDecreasing);
    blackWhiteGradient(HueMethod::kLonger);
}

make_conical()

static sk_sp< SkShader > make_conical ( const GradRun &  run, SkTileMode  mode  )

static

Definition at line 789 of file gradients.cpp.

                                                                         {
    const SkScalar half = SIZE * 0.5f;
    const SkPoint center { half, half };
    return SkGradientShader::MakeTwoPointConical(center, 20, center, half - 10,
                                                 run.fColors, run.fPos, run.fCount, mode);
}

make_linear()

static sk_sp< SkShader > make_linear ( const GradRun &  run, SkTileMode  mode  )

static

Definition at line 778 of file gradients.cpp.

                                                                        {
    const SkPoint pts[] { { 30, 30 }, { SIZE - 30, SIZE - 30 } };
    return SkGradientShader::MakeLinear(pts, run.fColors, run.fPos, run.fCount, mode);
}

make_radial()

static sk_sp< SkShader > make_radial ( const GradRun &  run, SkTileMode  mode  )

static

Definition at line 783 of file gradients.cpp.

                                                                        {
    const SkScalar half = SIZE * 0.5f;
    return SkGradientShader::MakeRadial({half,half}, half - 10, run.fColors, run.fPos,
                                        run.fCount, mode);
}

make_sweep()

static sk_sp< SkShader > make_sweep ( const GradRun &  run, SkTileMode    )

static

Definition at line 796 of file gradients.cpp.

                                                                  {
    const SkScalar half = SIZE * 0.5f;
    return SkGradientShader::MakeSweep(half, half, run.fColors, run.fPos, run.fCount);
}