Painting lines

[therealjag]

hey there i am trying to create links between nodes that i have made but theres 1 problem. everytime i paint a link the last link that i painted onto the qpainter goes away. how can i keep the links that have been painted before on the link? i store the node Id's in an array and their position with a struct. so i just get a user input as to where they want the link to be created. my code for the painting is shown below:

if( drawLine == 1)
    {	
	    painter.setPen(myTextColor());	 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
 
    }

if( drawLine == 1)
    {	
	    painter.setPen(myTextColor());	 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
	 
    }

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i also have a capacity number that i wish to appear between the links when they get painted.

[jacek]

Where do you draw those lines? In paintEvent()?

[therealjag]

yeah in Paintevent. actaully it doesnt really matter where they get painted as long as they do!

[jacek]

How many lines do you paint in single call to paintEvent()?

[therealjag]

just the lines that have been created so far. so for example the nodes are created first and then the user presses a button to create the link. the link then gets created between the nodes that the user specifies and then the user can then go on to create the next link. i just want the links created so far to be printed...

[jacek]

Could you show more code from your paintEvent()?

[therealjag]

ok sure here is the code from the QPaintEvent and below it is the function that gets the user input:

void SortingBox::paintEvent(QPaintEvent * /* event */)
{
   QPainter painter(this);
   QPoint offset(7,13);
    int looplength=0;
    foreach (ShapeItem shapeItem, shapeItems) 
    {
 
	   QPoint mid(-shapeItem.position());
	   //QPoint offset(7,13);
	   QPoint text(100,100);
 
        painter.translate(shapeItem.position());
        painter.setBrush(shapeItem.color());
        painter.drawPath(shapeItem.path());
        painter.translate(-shapeItem.position());
        painter.setPen(initialItemColor());
	     painter.drawText((shapeItem.position() + offset),tr("%1").arg(shapeItem.instanceNumber()));
 
 
	    list.position[shapeItem.instanceNumber()] = shapeItem.position();
	    list.nodeID[shapeItem.instanceNumber()] = shapeItem.instanceNumber();
	    looplength = shapeItem.instanceNumber();
    }
 
    QPoint midpoint;
	 midpoint = ((list.position[n1] + list.position[n2])/2);
    QPoint test(100,100); 
    QSize textbox(100,100);
 
 
 
    if( drawLine == 1)
    {	
	    painter.setPen(myTextColor());
	    for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
 
 
	  }*/
 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
 
    }  
 }

void SortingBox::paintEvent(QPaintEvent * /* event */)
{
   QPainter painter(this);
   QPoint offset(7,13);
    int looplength=0;
    foreach (ShapeItem shapeItem, shapeItems) 
    {
	   
	   QPoint mid(-shapeItem.position());
	   //QPoint offset(7,13);
	   QPoint text(100,100);
	   
        painter.translate(shapeItem.position());
        painter.setBrush(shapeItem.color());
        painter.drawPath(shapeItem.path());
        painter.translate(-shapeItem.position());
        painter.setPen(initialItemColor());
	     painter.drawText((shapeItem.position() + offset),tr("%1").arg(shapeItem.instanceNumber()));

	    
	    list.position[shapeItem.instanceNumber()] = shapeItem.position();
	    list.nodeID[shapeItem.instanceNumber()] = shapeItem.instanceNumber();
	    looplength = shapeItem.instanceNumber();
    }
    
    QPoint midpoint;
	 midpoint = ((list.position[n1] + list.position[n2])/2);
    QPoint test(100,100); 
    QSize textbox(100,100);
    
    
        
    if( drawLine == 1)
    {	
	    painter.setPen(myTextColor());
	    for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
		
		
	  }*/
	 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
	 
    }  
 }

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function user input( )

void SortingBox::user_input()
{	
 drawLine = 1;
 
 
	 QLabel *integerLabel = new QLabel(this);
		 bool ok;
				n1 = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("enter first node to link:"), 25, 0, 100, 1, &ok);
 
				if(ok)
				integerLabel->setText(tr("%1").arg(n1));
 
							        	   n2 = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("enter second node to link:"), 25, 0, 100, 1, &ok);
 
				if(ok)
				integerLabel->setText(tr("%1").arg(n2));
 
							        	   topology[n1][n2] = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("required capacity:"), 25, 0, 100, 1, &ok);
 
				if(ok)
				integerLabel->setText(tr("%1").arg(topology[n1][n2]));
 
}

void SortingBox::user_input()
{	
 drawLine = 1;
	

	 QLabel *integerLabel = new QLabel(this);
		 bool ok;
				n1 = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("enter first node to link:"), 25, 0, 100, 1, &ok);
													            
				if(ok)
				integerLabel->setText(tr("%1").arg(n1));
				
							        	   n2 = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("enter second node to link:"), 25, 0, 100, 1, &ok);
													            
				if(ok)
				integerLabel->setText(tr("%1").arg(n2));
				
							        	   topology[n1][n2] = QInputDialog::getInteger(this, tr("QInputDialog::getInteger()"),
            													tr("required capacity:"), 25, 0, 100, 1, &ok);
													            
				if(ok)
				integerLabel->setText(tr("%1").arg(topology[n1][n2]));

}

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[jacek]

foreach (ShapeItem shapeItem, shapeItems) 
{
   //...
}

foreach (ShapeItem shapeItem, shapeItems) 
{
   //...
}

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What are these ShapeItems?

for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
 
 
	  }*/
 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
 
    }

for(int j=0;j<looplength;j++)
    	/*{
			if(list.nodeID[j]>0 && list.nodeID[j]<100)
			{
	   	painter.drawLine( list.position[list.nodeID[j]]+offset, list.position[list.nodeID[j+1]]+offset );
	   	}
		
		
	  }*/
	 
	   painter.drawLine( list.position[n1]+offset, list.position[n2]+offset );
		painter.drawText(QRect(midpoint,textbox),0,tr("%1").arg(topology[n1][n2]));
	 
    }

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Where do you change n1 and n2?

Your paintEvent() should be something like this:

for each edge in Edges:
   draw line from edge.startNode.point to edge.endNode.point
   draw text edge.label at midPoint( edge.startNode.point, edge.endNode.point )

for each edge in Edges:
   draw line from edge.startNode.point to edge.endNode.point
   draw text edge.label at midPoint( edge.startNode.point, edge.endNode.point )

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[therealjag]

Quote:
Qt Code:
foreach (ShapeItem shapeItem, shapeItems) { //...}

What are these ShapeItems?

the shapeItems are just my nodes that i have created. they arent linked in any programmable way like in a linked list or anything they have just been created individually.
n1 and n2 get changed when the user enters their value so the first user input gets set to n1 and the second user input gets set to n2. the capacity for the link then gets asked for after that.

[jacek]

n1 and n2 get changed when the user enters their value so the first user input gets set to n1 and the second user input gets set to n2. the capacity for the link then gets asked for after that.

So in fact your paintEvent() draws only one edge?

[therealjag]

yeah it only draws 1 edge at a time but is there a way to keep the older ones drawn on the screen?