動く絵文字メーカー

GifMaker.cpp

# include <Siv3D.hpp> // OpenSiv3D v0.4.3

// https://siv3d.github.io/ja-jp/news/v043/#3-gif
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 saveGif(String path, String str, Color fgColor, Color bgColor) {
    const int size = 128;
    MSRenderTexture renderTexture(size, size);

    const Font font(60, Typeface::Heavy);

    // GIF アニメ出力クラス
    AnimatedGIFWriter gif(path, size / 2, size / 2);

    AnimationTexture animation;

    auto length = 30;
    const auto width = font(str).region().w;
    for(auto i : step(length)) 
    {
        renderTexture.clear(fgColor);
        {
            ScopedRenderTarget2D renderTarget(renderTexture);

            double dx = (double)str.size() * 3 *  i;
            Transformer2D transform(Mat3x2::Translate(Vec2::Left() * dx + Vec2::Right() * width));
            
            font(str).drawAt(64, 64, bgColor);
        }

        {
            Graphics2D::Flush();
            renderTexture.resolve();
        }

        Image image;
        renderTexture.readAsImage(image);

        // GIF アニメのフレームとして書き出し
        gif.writeFrame(image.scaled(size / 2, size / 2), 0.1s);
    }    

    gif.close();
}

void Main()
{   
    HSV fontColor = Palette::Orange, bgColor = Palette::White;
    TextEditState text(U"emoji");
    AnimatedGIFReader reader;
    AnimationTexture animation;
    
    Window::SetTitle(U"動く絵文字メーカー");

    while (System::Update())
    {
        SimpleGUI::Headline(U"文字色", Vec2(240, 20));
        {
            // カラーピッカー
            SimpleGUI::ColorPicker(fontColor, Vec2(240, 60));
        }
        SimpleGUI::Headline(U"背景色", Vec2(20, 20));
        {
            // カラーピッカー
            SimpleGUI::ColorPicker(bgColor, Vec2(20, 60));
        }

        SimpleGUI::TextBox(text, Vec2(20, 200));
        if (SimpleGUI::Button(U"Save", Vec2(320, 200))) {
            auto path = text.text + U".gif";
            saveGif(path, text.text, fontColor, bgColor);

            const AnimatedGIFReader gif(path);

            Array<Image> images;

            if (gif.read(images, animation.delays, animation.duration))
            {
                animation.textures = images.map([](const Image& i) { return Texture(i); });
            }
        }

        const int32 timeMillisec = static_cast<int32>(Scene::Time() * 1000);

        if (animation.frames() > 0) {
            animation.getTexture(timeMillisec).draw(Vec2(20, 400));
        }
        
    }
}