gm/lcdblendmodes.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "gm/gm.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkFont.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkPaint.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/SkSurface.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypeface.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkGradient.h"
#include "tools/ToolUtils.h"
#include "tools/fonts/FontToolUtils.h"

#include <array>

namespace skiagm {

constexpr int kColWidth = 180;
constexpr int kNumCols = 4;
constexpr int kWidth = kColWidth * kNumCols;
constexpr int kHeight = 750;

static sk_sp<SkShader> make_shader(const SkRect& bounds) {
    const SkPoint pts[] = {
        { bounds.left(), bounds.top() },
        { bounds.right(), bounds.bottom() },
    };
    const SkColor4f colors[] = {
        SkColors::kRed, SkColors::kGreen,
    };
    return SkShaders::LinearGradient(pts, {{colors, {}, SkTileMode::kRepeat}, {}});
}

class LcdBlendGM : public skiagm::GM {
public:
    LcdBlendGM() {
        const int kPointSize = 25;
        fTextHeight = SkIntToScalar(kPointSize);
    }

protected:
    SkString getName() const override { return SkString("lcdblendmodes"); }

    void onOnceBeforeDraw() override {
        fCheckerboard = ToolUtils::create_checkerboard_shader(SK_ColorBLACK, SK_ColorWHITE, 4);
    }

    SkISize getISize() override { return SkISize::Make(kWidth, kHeight); }

    void onDraw(SkCanvas* canvas) override {
        SkPaint p;
        p.setAntiAlias(false);
        p.setStyle(SkPaint::kFill_Style);
        p.setShader(fCheckerboard);
        SkRect r = SkRect::MakeWH(SkIntToScalar(kWidth), SkIntToScalar(kHeight));
        canvas->drawRect(r, p);

        SkImageInfo info = SkImageInfo::MakeN32Premul(kWidth, kHeight);
        SkSurfaceProps props = SkSurfaceProps(0, kRGB_H_SkPixelGeometry);
        auto surface(ToolUtils::makeSurface(canvas, info, &props));

        SkCanvas* surfCanvas = surface->getCanvas();
        this->drawColumn(surfCanvas, SK_ColorBLACK, SK_ColorWHITE, false);
        surfCanvas->translate(SkIntToScalar(kColWidth), 0);
        this->drawColumn(surfCanvas, SK_ColorWHITE, SK_ColorBLACK, false);
        surfCanvas->translate(SkIntToScalar(kColWidth), 0);
        this->drawColumn(surfCanvas, SK_ColorGREEN, SK_ColorMAGENTA, false);
        surfCanvas->translate(SkIntToScalar(kColWidth), 0);
        this->drawColumn(surfCanvas, SK_ColorCYAN, SK_ColorMAGENTA, true);

        SkPaint surfPaint;
        surfPaint.setBlendMode(SkBlendMode::kSrcOver);
        surface->draw(canvas, 0, 0, SkSamplingOptions(), &surfPaint);
    }

    void drawColumn(SkCanvas* canvas, SkColor backgroundColor, SkColor textColor, bool useGrad) {
        static constexpr auto gModes = std::to_array<SkBlendMode>({
                SkBlendMode::kClear,
                SkBlendMode::kSrc,
                SkBlendMode::kDst,
                SkBlendMode::kSrcOver,
                SkBlendMode::kDstOver,
                SkBlendMode::kSrcIn,
                SkBlendMode::kDstIn,
                SkBlendMode::kSrcOut,
                SkBlendMode::kDstOut,
                SkBlendMode::kSrcATop,
                SkBlendMode::kDstATop,
                SkBlendMode::kXor,
                SkBlendMode::kPlus,
                SkBlendMode::kModulate,
                SkBlendMode::kScreen,
                SkBlendMode::kOverlay,
                SkBlendMode::kDarken,
                SkBlendMode::kLighten,
                SkBlendMode::kColorDodge,
                SkBlendMode::kColorBurn,
                SkBlendMode::kHardLight,
                SkBlendMode::kSoftLight,
                SkBlendMode::kDifference,
                SkBlendMode::kExclusion,
                SkBlendMode::kMultiply,
                SkBlendMode::kHue,
                SkBlendMode::kSaturation,
                SkBlendMode::kColor,
                SkBlendMode::kLuminosity,
        });
        // Draw background rect
        SkPaint backgroundPaint;
        backgroundPaint.setColor(backgroundColor);
        canvas->drawRect(SkRect::MakeIWH(kColWidth, kHeight), backgroundPaint);
        SkScalar y = fTextHeight;
        for (size_t m = 0; m < std::size(gModes); m++) {
            SkPaint paint;
            paint.setColor(textColor);
            paint.setBlendMode(gModes[m]);
            SkFont font(ToolUtils::DefaultPortableTypeface(), fTextHeight);
            font.setSubpixel(true);
            font.setEdging(SkFont::Edging::kSubpixelAntiAlias);
            if (useGrad) {
                SkRect r;
                r.setXYWH(0, y - fTextHeight, SkIntToScalar(kColWidth), fTextHeight);
                paint.setShader(make_shader(r));
            }
            SkString string(SkBlendMode_Name(gModes[m]));
            canvas->drawString(string, 0, y, font, paint);
            y+=fTextHeight;
        }
    }

private:
    SkScalar fTextHeight;
    sk_sp<SkShader> fCheckerboard;
    using INHERITED = skiagm::GM;
};

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

DEF_GM( return new LcdBlendGM; )
}  // namespace skiagm