#include <QtGui/QApplication>
#include <QtGui/QMainWindow>
#include <QThread>
#include <QWidget>
#include <QImage>
#include <QPainter>
#include <QTimer>
#include <QMutex>

QMutex g_mutex;

class Canvas : public QWidget
{
	Q_OBJECT
public:
	Canvas(QWidget* parent=0);

	void drawStuff();

protected:
	void paintEvent(QPaintEvent *);

	QImage m_image;
};

class RenderThread : public QThread
{
public:
	RenderThread(Canvas* canvas) : m_canvas(canvas), m_stopping(false) {}

	void run();
	void stop()		{ m_stopping = true; }

private:
	Canvas* m_canvas;
	bool m_stopping;
};


class MainWindow : public QMainWindow
{
	Q_OBJECT

public:
	MainWindow(QWidget *parent = 0);
	~MainWindow();

private:
	RenderThread* m_renderThread;
};

Canvas::Canvas(QWidget *parent)
:	QWidget(parent),
	m_image(256,256, QImage::Format_ARGB32_Premultiplied)
{
	m_image.fill(0xffffffff);
}

void Canvas::drawStuff()
{
	g_mutex.lock();

	m_image.fill(0xffffffff);

	QPainter painter(&m_image);
	QPen pen(QColor(40,90,180,200));
	pen.setWidthF(12.0f);
	painter.setPen(pen);
	painter.drawLine(QPointF(0,0), QPointF(256,256));

	g_mutex.unlock();
}

void Canvas::paintEvent(QPaintEvent *)
{
	g_mutex.lock();

	QPainter p(this);
	p.drawImage(0,0, m_image);

	g_mutex.unlock();
}

void RenderThread::run()
{
	while(!m_stopping)
	{
		m_canvas->drawStuff();
		msleep(10);
	}
}

MainWindow::MainWindow(QWidget *parent)
	: QMainWindow(parent)
{
	Canvas* canvas = new Canvas(this);
	setCentralWidget(canvas);

	m_renderThread = new RenderThread(canvas);
	m_renderThread->start();
}

MainWindow::~MainWindow()
{
	m_renderThread->stop();
	m_renderThread->wait();

	delete m_renderThread;
}


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

#include "main.moc"