VideoPlayerOnSiv3D.cpp

# include <Siv3D.hpp>

// アニメーション描画用のクラス
struct AnimationTexture
{
    Array<Texture> textures;

    // フレームの時間
    Array<int32> delays;
    
    int32 duration = 0;

    explicit operator bool() const noexcept
    {
        return !textures.isEmpty();
    }

    Size size() const noexcept
    {
        if (!textures)
        {
            return Size(0, 0);
        }

        return textures.front().size();
    }

    size_t frames() const noexcept
    {
        return textures.size();
    }

    size_t getFrameIndex(int32 timeMillisec) const noexcept
    {
        return AnimatedGIFReader::MillisecToIndex(timeMillisec, delays, duration);
    }

    const Texture& getTexture(int32 timeMillisec) const noexcept
    {
        return textures[getFrameIndex(timeMillisec)];
    }
};

void Main()
{
    AnimationTexture animation;
    {
        // GIF ファイルを開く
        const AnimatedGIFReader gif(U"example/sample.gif");

        if (!gif)
        {
            throw Error(U"Failed to open a gif file");
        }

        Array<Image> images;

        // GIF アニメーションを読み込み
        if (gif.read(images, animation.delays, animation.duration))
        {
            // Image を Texture に変換
            animation.textures = images.map([](const Image& i) { return Texture(i); });
        }
        else
        {
            throw Error(U"Failed to load a gif animation");
        }
    }

    // 画像のサイズ、フレーム数、アニメーションの長さ（ミリ秒）
    // Print << U"{}, {} frames ({} ms)"_fmt(animation.size(), animation.frames(), animation.duration);

    const Point pos(10, 10);

    double time = 0.0;
    auto button = U"▶";
    double rate = 1.0f;
    auto loopTime = animation.duration * 0.001;

    const Font font(20);

    while (System::Update())
    {
        time += Scene::DeltaTime() * rate;

        if (time > loopTime) {
            time -= loopTime;
        }

        if (SimpleGUI::Button(button, Vec2(20, 500))) {
            if (button == U"▶") {
                rate = 0.0f;
                button = U"⏹️";
            } else {
                rate = 1.0f;
                button = U"▶";
            }
        }

        if (SimpleGUI::Slider(time, 0.0, loopTime, Vec2(180, 500), 600)) {
            rate = 0.0f;
            button = U"⏹️";
        }

        font(U"{:3.2f}"_fmt(time)).draw(100, 500);
        animation.getTexture(static_cast<int32>(time * 1000)).scaled(1.5).draw(pos);
        // animation.getTexture(static_cast<int32>(time * 1000)).draw(pos);
    }
}