Create QGrapchisObject in sub QThread, but not Efficiency promotion

[cybfly]

Hi, Everyone.
I am using QGraphicsView system to show a layout in chip design system.(EDA tools like Virtuso、Thunder、ICC)
And the max amount of QGraphicsObject/QGraphicsItem can be 500,000+, or even more.
Thus i have problem making items easy and quick to be drawn or view in the scene.
I followed the Chips demo, and query the solutions from Google, also read lots of topics in QtCentre.
But still i did not find a viable solution, Also Text item impact enormous.
Out group use the tree structure to organize the objects, which use a root item as the top level item, and then level 2, level 3...
But the users always need to flat all the items. And Then i use QTransform()::m11() to control the shape the item is paint.
But with so many items inside even this methods does not work.

There are two difficult parts on this case：
1）how to reduce the loading time for creating QGraphicsItem.
2）how to make it smoother while zoom in/zoom out, with so many items.

Codes below are the sample i tried to use QThread to save loading time. But it does not work, or the program works
bad than no sub thread is used to load the items. I am very curious why the program has no response when i used sub thread,
and the program runs smoother with no sub thread.

Thanks all.

// Used to as Root item
class CRoot: public QGraphicsObject
{
public:
	CRoot(QGraphicsObject *opParent = NULL) : QGraphicsObject(opParent)
	{}
 
	QRectF boundingRect() { return QRectF(); } 
	...
};
 
// Leaf Item
class Chip : public QGraphicsObject
{
	...
	void paint(QPainter *opPainter, const QStyleOptionGraphicsItem *opOPtion, QWidget *opWidget)
	{
		Q_UNUSED(opOPtion);
		Q_UNUSED(opWidget);
		opPainter->save();
		double d_value = mdWidth * transform().m11();
		if (d_value >= 7)
		{
			opPainter->drawShape(moShape);
		}
		else
		{
			opPainter->drawPoint(0, 0);
		}
 
		opPainter->restore();
	}
 
private:
	QPainterPath moShape; // used to store the path of Chip
	QGraphicsTextItem *mopLabel; // Label item of this cell.
};
 
class CLayout : public QGraphicsObject
{
	Q_OBJECT
public:
	CLayout(QGraphicsObject *opParent = NULL) : QGraphicsObject(opParent)
	{
 
	}
 
	CRoot *mopGetRoot() 
	{
		QReadLocker o_locker(&moLock); 
		return mopRoot;
	}
signals:
	void msigLoadDone();
 
public slots:
	void mslotLoadItems()
	{
		QWriteLocker o_locker(&moLock);
		mopRoot = new CRoot;
 
		const int I_COUNT = 500000;
		for (int i_cnt = 0; i_cnt < I_COUNT; ++i_cnt)
		{
			Chip *op_chip = new chip(CRoot);
			op_chip->setPos(i_cnt / 10000, i_cnt / 10000);
			mlstopItems.push_back(op_chip);
		}
 
		// move items from curThread to GUI thread.
		moveToThread(QApplication::instance()->thread());
		mopRoot->moveToThread(QApplication::instance()->thread());
		foreach(Chip *op_item, mlstopItems)
		{
			op_item->moveToThread(QApplication::instance()->thread());
		}
 
		emit msigLoadDone();
	}
 
private:
	CRoot *mopRoot;
	QList<Chip *> mlstopItems;
	QReadWriteLock moLock;
};
 
class CMainWindow: public QMainWindow
{
	Q_OBJECT
public:
	...
	void mvInitScene()
	{
		mopScene = new QGraphicsScene();
	}
 
signals:
	void msigGoToLoad();
 
public slots:
	void mslotSetRootItem()
	{
		std::call_once(meFlag, &CMainWindow::mvInitScene, this);
		mopScene()->addItem(mopLayout->mopGetRoot());
	}
 
	void mslotBtnClicked()
	{
		mopThread = new QThread();
		mopLayout = new Layout();
 
	#ifdef USED_THREAD
		connect(this, SIGNAL(msigGoToLoad()), mopLayout, SLOT(mslotLoadItems()));
		connect(mopLayout, SIGNAL(msigLoadDone()), this, SLOT(mslotSetRootItem()));
		connect(mopThread, SIGNAL(finished()), mopThread, SLOT(deleteLater()));
		mopLayout->moveToThread(mopThread);
		mopThread->start();
	#else
		mopLayout->mslotLOadItems();
		mslotSetRootItem();
	#endif
		emit msigGoToLoad();
	}
private:
	QThread *mopThread;
	CLayout *mopLayout;
	QGraphicsScene *mopScene;
	std::once_flag meFlag;
};

// Used to as Root item
class CRoot: public QGraphicsObject
{
public:
	CRoot(QGraphicsObject *opParent = NULL) : QGraphicsObject(opParent)
	{}
	
	QRectF boundingRect() { return QRectF(); } 
	...
};

// Leaf Item
class Chip : public QGraphicsObject
{
	...
	void paint(QPainter *opPainter, const QStyleOptionGraphicsItem *opOPtion, QWidget *opWidget)
	{
		Q_UNUSED(opOPtion);
		Q_UNUSED(opWidget);
		opPainter->save();
		double d_value = mdWidth * transform().m11();
		if (d_value >= 7)
		{
			opPainter->drawShape(moShape);
		}
		else
		{
			opPainter->drawPoint(0, 0);
		}
		
		opPainter->restore();
	}
	
private:
	QPainterPath moShape; // used to store the path of Chip
	QGraphicsTextItem *mopLabel; // Label item of this cell.
};

class CLayout : public QGraphicsObject
{
	Q_OBJECT
public:
	CLayout(QGraphicsObject *opParent = NULL) : QGraphicsObject(opParent)
	{
		
	}
	
	CRoot *mopGetRoot() 
	{
		QReadLocker o_locker(&moLock); 
		return mopRoot;
	}
signals:
	void msigLoadDone();
		
public slots:
	void mslotLoadItems()
	{
		QWriteLocker o_locker(&moLock);
		mopRoot = new CRoot;
		
		const int I_COUNT = 500000;
		for (int i_cnt = 0; i_cnt < I_COUNT; ++i_cnt)
		{
			Chip *op_chip = new chip(CRoot);
			op_chip->setPos(i_cnt / 10000, i_cnt / 10000);
			mlstopItems.push_back(op_chip);
		}
		
		// move items from curThread to GUI thread.
		moveToThread(QApplication::instance()->thread());
		mopRoot->moveToThread(QApplication::instance()->thread());
		foreach(Chip *op_item, mlstopItems)
		{
			op_item->moveToThread(QApplication::instance()->thread());
		}
		
		emit msigLoadDone();
	}
	
private:
	CRoot *mopRoot;
	QList<Chip *> mlstopItems;
	QReadWriteLock moLock;
};

class CMainWindow: public QMainWindow
{
	Q_OBJECT
public:
	...
	void mvInitScene()
	{
		mopScene = new QGraphicsScene();
	}
	
signals:
	void msigGoToLoad();
	
public slots:
	void mslotSetRootItem()
	{
		std::call_once(meFlag, &CMainWindow::mvInitScene, this);
		mopScene()->addItem(mopLayout->mopGetRoot());
	}
	
	void mslotBtnClicked()
	{
		mopThread = new QThread();
		mopLayout = new Layout();
		
	#ifdef USED_THREAD
		connect(this, SIGNAL(msigGoToLoad()), mopLayout, SLOT(mslotLoadItems()));
		connect(mopLayout, SIGNAL(msigLoadDone()), this, SLOT(mslotSetRootItem()));
		connect(mopThread, SIGNAL(finished()), mopThread, SLOT(deleteLater()));
		mopLayout->moveToThread(mopThread);
		mopThread->start();
	#else
		mopLayout->mslotLOadItems();
		mslotSetRootItem();
	#endif
		emit msigGoToLoad();
	}
private:
	QThread *mopThread;
	CLayout *mopLayout;
	QGraphicsScene *mopScene;
	std::once_flag meFlag;
};

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