animator_example.cpp

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#ifndef animator_DEFINED
#define animator_DEFINED

#include <memory>
#include "skia.h"

struct Animator {
    virtual ~Animator() {}
    virtual void draw(SkCanvas*, double frame) = 0;
};

std::unique_ptr<Animator> MakeAnimator(SkISize, const SkImage*);

#endif  // animator_DEFINED

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

//struct Draw : public Animator {
//    const SkImage* image;
//    SkISize size;
//    // INSERT FIELDS HERE
//    Draw(SkISize s, const SkImage* i) : image(i), size(s) {
//        // INSERT CODE HERE
//    }
//    void draw(SkCanvas* canvas, double frame) override {
//        // INSERT CODE HERE
//    }
//};
//
//std::unique_ptr<Animator> MakeAnimator(SkISize s, const SkImage* i) {
//    return std::unique_ptr<Animator>(new Draw(s, i));
//}

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

struct Draw : public Animator {
    const SkImage* image;
    SkISize size;
    SkPath star;
    SkPaint paint;
    Draw(SkISize s, const SkImage* i) : image(i), size(s) {
        const SkScalar R = 0.45f * SkTMin(size.width(), size.height());
        star.moveTo(R, 0);
        for (int i = 1; i < 8; ++i) {
            SkScalar a = 2.6927937f * i;
            star.lineTo(R * cos(a), R * sin(a));
        }
        paint.setShader(image->makeShader(SkShader::kRepeat_TileMode,
                                          SkShader::kRepeat_TileMode));
    }
    void draw(SkCanvas* canvas, double frame) override {
        canvas->translate(0.5 * size.width(), 0.5 *  size.height());
        canvas->rotate(frame * 360);
        canvas->clear(SkColorSetARGB(255, 255, 255, 255));
        canvas->drawPath(star, paint);
    }
};

std::unique_ptr<Animator> MakeAnimator(SkISize s, const SkImage* i) {
    return std::unique_ptr<Animator>(new Draw(s, i));
}

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

static void output(int i, SkData* data) {
    // For sandboxed applications, change this function to just dump to stdout.
    static const char outputPrefix[] = "/tmp/animator";
    auto outputPath = SkStringPrintf("%s_%04d.png", outputPrefix, i);
    SkFILEWStream ofile(outputPath.c_str());
    if (!ofile.isValid()) { abort(); }
    ofile.write(data->data(), data->size());
}

int main() {
    static const char imagePath[] = "resources/mandrill_512_q075.jpg";
    const int frameCount = 60;
    const SkISize size = {256, 256};

    auto image = SkImage::MakeFromEncoded(SkData::MakeFromFileName(imagePath));
    auto animator = MakeAnimator(size, image.get());
    auto surface = SkSurface::MakeRasterN32Premul(size.width(), size.height());
    double frameLength = 1.0 / frameCount;
    for (int i = 0; i < frameCount; ++i) {
        SkCanvas* canvas = surface->getCanvas();
        SkAutoCanvasRestore autoCanvasRestore(canvas, true);
        animator->draw(canvas, i * frameLength);
        sk_sp<SkData> encoded(surface->makeImageSnapshot()->encode());
        output(i, encoded.get());
    }
}