gm/srcmode.cpp

/*
 * Copyright 2012 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/SkPath.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>

#define W   SkIntToScalar(80)
#define H   SkIntToScalar(60)

typedef void (*PaintProc)(SkPaint*);

static void identity_paintproc(SkPaint* paint) {
    paint->setShader(nullptr);
}

static void gradient_paintproc(SkPaint* paint) {
    const SkColor4f colors[] = { SkColors::kGreen, SkColors::kBlue };
    const SkPoint pts[] = { { 0, 0 }, { W, H } };
    paint->setShader(SkShaders::LinearGradient(pts, {{colors, {}, SkTileMode::kClamp}, {}}));
}

typedef void (*Proc)(SkCanvas*, const SkPaint&, const SkFont&);

static void draw_hair(SkCanvas* canvas, const SkPaint& paint, const SkFont&) {
    SkPaint p(paint);
    p.setStrokeWidth(0);
    canvas->drawLine(0, 0, W, H, p);
}

static void draw_thick(SkCanvas* canvas, const SkPaint& paint, const SkFont&) {
    SkPaint p(paint);
    p.setStrokeWidth(H/5);
    canvas->drawLine(0, 0, W, H, p);
}

static void draw_rect(SkCanvas* canvas, const SkPaint& paint, const SkFont&) {
    canvas->drawRect(SkRect::MakeWH(W, H), paint);
}

static void draw_oval(SkCanvas* canvas, const SkPaint& paint, const SkFont&) {
    canvas->drawOval(SkRect::MakeWH(W, H), paint);
}

static void draw_text(SkCanvas* canvas, const SkPaint& paint, const SkFont& font) {
    canvas->drawString("Hamburge", 0, H*2/3, font, paint);
}

class SrcModeGM : public skiagm::GM {
    SkPath fPath;

    void onOnceBeforeDraw() override { this->setBGColor(SK_ColorBLACK); }

    SkString getName() const override { return SkString("srcmode"); }

    SkISize getISize() override { return {640, 760}; }

    void drawContent(SkCanvas* canvas) {
        canvas->translate(SkIntToScalar(20), SkIntToScalar(20));

        SkPaint paint;
        SkFont  font(ToolUtils::DefaultPortableTypeface(), H / 4);
        paint.setColor(0x80F60000);

        static constexpr auto procs = std::to_array<Proc>({
                draw_hair,
                draw_thick,
                draw_rect,
                draw_oval,
                draw_text,
        });

        static constexpr auto modes = std::to_array<SkBlendMode>({
                SkBlendMode::kSrcOver,
                SkBlendMode::kSrc,
                SkBlendMode::kClear,
        });

        static constexpr auto paintProcs =
                std::to_array<PaintProc>({identity_paintproc, gradient_paintproc});

        for (int aa = 0; aa <= 1; ++aa) {
            paint.setAntiAlias(SkToBool(aa));
            font.setEdging(SkToBool(aa) ? SkFont::Edging::kAntiAlias : SkFont::Edging::kAlias);
            canvas->save();
            for (size_t i = 0; i < std::size(paintProcs); ++i) {
                paintProcs[i](&paint);
                for (size_t x = 0; x < std::size(modes); ++x) {
                    paint.setBlendMode(modes[x]);
                    canvas->save();
                    for (size_t y = 0; y < std::size(procs); ++y) {
                        procs[y](canvas, paint, font);
                        canvas->translate(0, H * 5 / 4);
                    }
                    canvas->restore();
                    canvas->translate(W * 5 / 4, 0);
                }
            }
            canvas->restore();
            canvas->translate(0, (H * 5 / 4) * std::size(procs));
        }
    }

    static sk_sp<SkSurface> compat_surface(SkCanvas* canvas, const SkISize& size) {
        SkImageInfo info = SkImageInfo::MakeN32Premul(size);
        sk_sp<SkSurface> surface = canvas->makeSurface(info);
        if (nullptr == surface) {
            // picture canvas will return null, so fall-back to raster
            surface = SkSurfaces::Raster(info);
        }
        return surface;
    }

    void onDraw(SkCanvas* canvas) override {
        auto surf(compat_surface(canvas, this->getISize()));
        surf->getCanvas()->drawColor(SK_ColorWHITE);
        this->drawContent(surf->getCanvas());
        surf->draw(canvas, 0, 0);
    }
};

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

DEF_GM(return new SrcModeGM;)