#include <memory>
#include <QtCore>
#include <QtGui>
#include <QtOpenGL>

void paintPath(QPaintDevice *device)
{
    QPainter painter(device);
    painter.setRenderHint(QPainter::Antialiasing);

    QPainterPath path;
    path.addRect(20, 20, 60, 60);
    path.moveTo(0, 0);
    path.cubicTo(99, 0, 50, 50, 99, 99);
    path.cubicTo(0, 99, 50, 50, 0, 0);

    painter.fillRect(0, 0, 200, 200, Qt::white);
    painter.setPen(QPen(QColor(79, 106, 25), 1, Qt::SolidLine,
                        Qt::FlatCap, Qt::MiterJoin));
    painter.setBrush(QColor(122, 163, 39));
    painter.drawPath(path);

    painter.end();
}

class GLWidget : public QGLWidget
{
public:
    GLWidget(QWidget *parent = 0) : QGLWidget(parent), fbo(0)
    {
        setFixedSize(200, 200);
    }

protected:
    void initializeGL()
    {
        fbo.reset(new QGLFramebufferObject(200, 200));
        paintPath(fbo.get());
    }

    void resizeGL(int w, int h)
    {
        glViewport(0, 0, w, h);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        gluOrtho2D(0.0f, w, h, 0.0f);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
    }

    void paintEvent(QPaintEvent *)
    {
        QPainter painter(this);
        drawTexture(QPoint(), fbo->texture());
    }

private:
    std::auto_ptr<QGLFramebufferObject> fbo;
};

class Widget : public QWidget
{
public:
    Widget(QWidget *parent) : QWidget(parent)
    {
        setFixedSize(200, 200);
    }

protected:
    void paintEvent(QPaintEvent *)
    {
        paintPath(this);
    }
};

class Window : public QWidget
{
public:
    Window() : QWidget()
    {
        Widget *native = new Widget(this);
        GLWidget *openGL = new GLWidget(this);
        QLabel *nativeLabel = new QLabel(tr("Native"));
        nativeLabel->setAlignment(Qt::AlignHCenter);
        QLabel *openGLLabel = new QLabel(tr("OpenGL FBO"));
        openGLLabel->setAlignment(Qt::AlignHCenter);

        QGridLayout *layout = new QGridLayout;
        layout->addWidget(native, 0, 0);
        layout->addWidget(openGL, 0, 1);
        layout->addWidget(nativeLabel, 1, 0);
        layout->addWidget(openGLLabel, 1, 1);
        setLayout(layout);

        setWindowTitle(tr("Native and OpenGL Widgets"));
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Window w;
    w.show();
    return app.exec();
}